Allow binding of custom ProjectRequest

This commit allows a custom instance to easily bind incoming request
attributes to a custom ProjectRequest instance and map it to a custom
ProjectDescription as well.

Closes gh-990

initializr-docs/src/main/asciidoc/configuration-guide.adoc

@@ -1069,3 +1069,32 @@ expiration settings accordingly.
 |Cache templates that are used to generate projects.
 
 |===
+
+
+
+[[create-instance-advanced-config-custom-project-request]]
+=== Bind to custom project request
+Only attributes that are defined in the metadata can be bound to a `ProjectRequest` and
+ultimately made available in `ProjectDescription`. A custom instance may chose however to
+provide additional attributes. Please note that those attributes won't be supported by
+official clients (i.e. IDEs).
+
+The first step is to define a custom `ProjectRequest` with your additional attributes and
+create a custom `ProjectGenerationController` that binds to it:
+
+[source,java,indent=0,subs="verbatim,quotes,attributes"]
+----
+include::{code-examples}/doc/generator/project/CustomProjectGenerationController.java[tag=code]
+----
+
+If you inherit from `WebProjectRequest`, defaults can be automatically applied from the
+metadata as shown above but you may also chose to ignore that. If you define a `@Bean`
+for that controller, the auto-configuration will back-off and use yours instead.
+
+The next step is to make sure that those additional attributes are made available in the
+`ProjectGenerationContext`. The idiomatic way of doing this is to create your own
+interface that extends from `ProjectDescription` and expose your custom attributes. To
+make sure your view of `ProjectGeneration` is made available in the
+`ProjectGenerationContext`, a custom `ProjectRequestToDescriptionConverter` should be
+defined. When such a bean exists in the context it replaces the default that the
+auto-configuration provides.

initializr-docs/src/main/java/io/spring/initializr/doc/generator/project/CustomProjectGenerationController.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.doc.generator.project;
+
+import java.util.Map;
+
+import io.spring.initializr.metadata.InitializrMetadataProvider;
+import io.spring.initializr.web.controller.ProjectGenerationController;
+import io.spring.initializr.web.project.ProjectGenerationInvoker;
+
+/**
+ * Example of a custom {@link ProjectGenerationController}.
+ *
+ * @author Stephane Nicoll
+ */
+// tag::code[]
+public class CustomProjectGenerationController extends ProjectGenerationController<CustomProjectRequest> {
+
+	public CustomProjectGenerationController(InitializrMetadataProvider metadataProvider,
+			ProjectGenerationInvoker projectGenerationInvoker) {
+		super(metadataProvider, projectGenerationInvoker);
+	}
+
+	@Override
+	public CustomProjectRequest projectRequest(Map<String, String> headers) {
+		CustomProjectRequest request = new CustomProjectRequest();
+		request.getParameters().putAll(headers);
+		request.initialize(getMetadata());
+		return request;
+	}
+
+}
+// end::code[]

initializr-docs/src/main/java/io/spring/initializr/doc/generator/project/CustomProjectRequest.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.doc.generator.project;
+
+import io.spring.initializr.web.project.WebProjectRequest;
+
+/**
+ * A sample custom {@link WebProjectRequest}.
+ *
+ * @author Stephane Nicoll
+ */
+public class CustomProjectRequest extends WebProjectRequest {
+
+}

initializr-web/src/main/java/io/spring/initializr/web/autoconfigure/InitializrAutoConfiguration.java

@@ -34,9 +34,11 @@ import io.spring.initializr.metadata.InitializrMetadataBuilder;
 import io.spring.initializr.metadata.InitializrMetadataProvider;
 import io.spring.initializr.metadata.InitializrProperties;
 import io.spring.initializr.web.controller.CommandLineMetadataController;
+import io.spring.initializr.web.controller.DefaultProjectGenerationController;
 import io.spring.initializr.web.controller.ProjectGenerationController;
 import io.spring.initializr.web.controller.ProjectMetadataController;
 import io.spring.initializr.web.controller.SpringCliDistributionController;
+import io.spring.initializr.web.project.DefaultProjectRequestToDescriptionConverter;
 import io.spring.initializr.web.project.ProjectGenerationInvoker;
 import io.spring.initializr.web.project.ProjectRequestToDescriptionConverter;
 import io.spring.initializr.web.support.DefaultDependencyMetadataProvider;
@@ -144,7 +146,7 @@ public class InitializrAutoConfiguration {
 		@ConditionalOnMissingBean
 		ProjectGenerationController projectGenerationController(InitializrMetadataProvider metadataProvider,
 				ProjectGenerationInvoker projectGenerationInvoker) {
-			return new ProjectGenerationController(metadataProvider, projectGenerationInvoker);
+			return new DefaultProjectGenerationController(metadataProvider, projectGenerationInvoker);
 		}
 
 		@Bean
@@ -171,14 +173,9 @@ public class InitializrAutoConfiguration {
 		@ConditionalOnMissingBean
 		ProjectGenerationInvoker projectGenerationInvoker(ApplicationContext applicationContext,
 				ApplicationEventPublisher eventPublisher,
-				ProjectRequestToDescriptionConverter projectRequestToDescriptionConverter) {
-			return new ProjectGenerationInvoker(applicationContext, eventPublisher,
-					projectRequestToDescriptionConverter);
-		}
-
-		@Bean
-		ProjectRequestToDescriptionConverter projectRequestToDescriptionConverter() {
-			return new ProjectRequestToDescriptionConverter();
+				ObjectProvider<ProjectRequestToDescriptionConverter> projectRequestToDescriptionConverter) {
+			return new ProjectGenerationInvoker(applicationContext, eventPublisher, projectRequestToDescriptionConverter
+					.getIfAvailable(DefaultProjectRequestToDescriptionConverter::new));
 		}
 
 		@Bean

initializr-web/src/main/java/io/spring/initializr/web/controller/DefaultProjectGenerationController.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.web.controller;
+
+import java.util.Map;
+
+import io.spring.initializr.metadata.InitializrMetadataProvider;
+import io.spring.initializr.web.project.ProjectGenerationInvoker;
+import io.spring.initializr.web.project.ProjectRequest;
+import io.spring.initializr.web.project.WebProjectRequest;
+
+/**
+ * A default {@link ProjectGenerationController} that uses a standard
+ * {@link ProjectRequest} to map parameters of a project generation request.
+ *
+ * @author Stephane Nicoll
+ */
+public class DefaultProjectGenerationController extends ProjectGenerationController<ProjectRequest> {
+
+	public DefaultProjectGenerationController(InitializrMetadataProvider metadataProvider,
+			ProjectGenerationInvoker projectGenerationInvoker) {
+		super(metadataProvider, projectGenerationInvoker);
+	}
+
+	@Override
+	public ProjectRequest projectRequest(Map<String, String> headers) {
+		WebProjectRequest request = new WebProjectRequest();
+		request.getParameters().putAll(headers);
+		request.initialize(getMetadata());
+		return request;
+	}
+
+}

initializr-web/src/main/java/io/spring/initializr/web/controller/ProjectGenerationController.java

@@ -33,12 +33,12 @@ import javax.servlet.http.HttpServletResponse;
 import io.spring.initializr.generator.buildsystem.BuildSystem;
 import io.spring.initializr.generator.buildsystem.maven.MavenBuildSystem;
 import io.spring.initializr.generator.project.ProjectDescription;
+import io.spring.initializr.metadata.InitializrMetadata;
 import io.spring.initializr.metadata.InitializrMetadataProvider;
 import io.spring.initializr.web.project.InvalidProjectRequestException;
 import io.spring.initializr.web.project.ProjectGenerationInvoker;
 import io.spring.initializr.web.project.ProjectGenerationResult;
 import io.spring.initializr.web.project.ProjectRequest;
-import io.spring.initializr.web.project.WebProjectRequest;
 import org.apache.commons.compress.archivers.ArchiveEntry;
 import org.apache.commons.compress.archivers.ArchiveOutputStream;
 import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
@@ -61,12 +61,13 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.ResponseBody;
 
 /**
- * {@link Controller} that provides endpoints for project generation.
+ * Base {@link Controller} that provides endpoints for project generation.
  *
+ * @param <R> the {@link ProjectRequest} type to use to bind request parameters
  * @author Stephane Nicoll
  */
 @Controller
-public class ProjectGenerationController {
+public abstract class ProjectGenerationController<R extends ProjectRequest> {
 
 	private static final Log logger = LogFactory.getLog(ProjectGenerationController.class);
 
@@ -80,12 +81,17 @@ public class ProjectGenerationController {
 		this.projectGenerationInvoker = projectGenerationInvoker;
 	}
 
+	/**
+	 * Create an initialized {@link ProjectRequest} instance to use to bind the parameters
+	 * of a project generation request.
+	 * @param headers the headers of the request
+	 * @return a new {@link ProjectRequest} instance
+	 */
 	@ModelAttribute
-	public ProjectRequest projectRequest(@RequestHeader Map<String, String> headers) {
-		WebProjectRequest request = new WebProjectRequest();
-		request.getParameters().putAll(headers);
-		request.initialize(this.metadataProvider.get());
-		return request;
+	public abstract R projectRequest(@RequestHeader Map<String, String> headers);
+
+	protected InitializrMetadata getMetadata() {
+		return this.metadataProvider.get();
 	}
 
 	@ExceptionHandler
@@ -96,7 +102,7 @@ public class ProjectGenerationController {
 
 	@RequestMapping(path = { "/pom", "/pom.xml" })
 	@ResponseBody
-	public ResponseEntity<byte[]> pom(ProjectRequest request) {
+	public ResponseEntity<byte[]> pom(R request) {
 		request.setType("maven-build");
 		byte[] mavenPom = this.projectGenerationInvoker.invokeBuildGeneration(request);
 		return createResponseEntity(mavenPom, "application/octet-stream", "pom.xml");
@@ -104,7 +110,7 @@ public class ProjectGenerationController {
 
 	@RequestMapping(path = { "/build", "/build.gradle" })
 	@ResponseBody
-	public ResponseEntity<byte[]> gradle(ProjectRequest request) {
+	public ResponseEntity<byte[]> gradle(R request) {
 		request.setType("gradle-build");
 		byte[] gradleBuild = this.projectGenerationInvoker.invokeBuildGeneration(request);
 		return createResponseEntity(gradleBuild, "application/octet-stream", "build.gradle");
@@ -112,7 +118,7 @@ public class ProjectGenerationController {
 
 	@RequestMapping("/starter.zip")
 	@ResponseBody
-	public ResponseEntity<byte[]> springZip(ProjectRequest request) throws IOException {
+	public ResponseEntity<byte[]> springZip(R request) throws IOException {
 		ProjectGenerationResult result = this.projectGenerationInvoker.invokeProjectStructureGeneration(request);
 		Path archive = createArchive(result, "zip", ZipArchiveOutputStream::new, ZipArchiveEntry::new,
 				ZipArchiveEntry::setUnixMode);
@@ -121,7 +127,7 @@ public class ProjectGenerationController {
 
 	@RequestMapping(path = "/starter.tgz", produces = "application/x-compress")
 	@ResponseBody
-	public ResponseEntity<byte[]> springTgz(ProjectRequest request) throws IOException {
+	public ResponseEntity<byte[]> springTgz(R request) throws IOException {
 		ProjectGenerationResult result = this.projectGenerationInvoker.invokeProjectStructureGeneration(request);
 		Path archive = createArchive(result, "tar.gz", this::createTarArchiveOutputStream, TarArchiveEntry::new,
 				TarArchiveEntry::setMode);
@@ -180,7 +186,7 @@ public class ProjectGenerationController {
 		return UnixStat.FILE_FLAG | (entryName.equals(wrapperScript) ? 0755 : UnixStat.DEFAULT_FILE_PERM);
 	}
 
-	private String generateFileName(ProjectRequest request, String extension) {
+	private String generateFileName(R request, String extension) {
 		String candidate = (StringUtils.hasText(request.getArtifactId()) ? request.getArtifactId()
 				: this.metadataProvider.get().getArtifactId().getContent());
 		String tmp = candidate.replaceAll(" ", "_");

initializr-web/src/main/java/io/spring/initializr/web/project/DefaultProjectRequestToDescriptionConverter.java

@@ -0,0 +1,252 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.web.project;
+
+import java.util.List;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+
+import io.spring.initializr.generator.buildsystem.BuildSystem;
+import io.spring.initializr.generator.language.Language;
+import io.spring.initializr.generator.packaging.Packaging;
+import io.spring.initializr.generator.project.MutableProjectDescription;
+import io.spring.initializr.generator.project.ProjectDescription;
+import io.spring.initializr.generator.version.Version;
+import io.spring.initializr.metadata.DefaultMetadataElement;
+import io.spring.initializr.metadata.Dependency;
+import io.spring.initializr.metadata.InitializrMetadata;
+import io.spring.initializr.metadata.Type;
+import io.spring.initializr.metadata.support.MetadataBuildItemMapper;
+
+import org.springframework.util.StringUtils;
+
+/**
+ * A default {@link ProjectRequestToDescriptionConverter} implementation that uses the
+ * {@link InitializrMetadata metadata} to set default values for missing attributes if
+ * necessary.
+ *
+ * @author Madhura Bhave
+ * @author HaiTao Zhang
+ */
+public class DefaultProjectRequestToDescriptionConverter implements ProjectRequestToDescriptionConverter {
+
+	private static final Version VERSION_1_5_0 = Version.parse("1.5.0.RELEASE");
+
+	private static final char[] VALID_MAVEN_SPECIAL_CHARACTERS = new char[] { '_', '-', '.' };
+
+	@Override
+	public ProjectDescription convert(ProjectRequest request, InitializrMetadata metadata) {
+		MutableProjectDescription description = new MutableProjectDescription();
+		convert(request, description, metadata);
+		return description;
+	}
+
+	/**
+	 * Validate the specified {@link ProjectRequest request} and initialize the specified
+	 * {@link ProjectDescription description}. Override any attribute of the description
+	 * that are managed by this instance.
+	 * @param request the request to validate
+	 * @param description the description to initialize
+	 * @param metadata the metadata instance to use to apply defaults if necessary
+	 */
+	public void convert(ProjectRequest request, MutableProjectDescription description, InitializrMetadata metadata) {
+		validate(request, metadata);
+		String springBootVersion = getSpringBootVersion(request, metadata);
+		List<Dependency> resolvedDependencies = getResolvedDependencies(request, springBootVersion, metadata);
+		validateDependencyRange(springBootVersion, resolvedDependencies);
+
+		description.setApplicationName(getApplicationName(request, metadata));
+		description.setArtifactId(getArtifactId(request, metadata));
+		description.setBaseDirectory(getBaseDirectory(request.getBaseDir(), request.getArtifactId()));
+		description.setBuildSystem(getBuildSystem(request, metadata));
+		description
+				.setDescription(determineValue(request.getDescription(), () -> metadata.getDescription().getContent()));
+		description.setGroupId(getGroupId(request, metadata));
+		description.setLanguage(Language.forId(request.getLanguage(), request.getJavaVersion()));
+		description.setName(getName(request, metadata));
+		description.setPackageName(getPackageName(request, metadata));
+		description.setPackaging(Packaging.forId(request.getPackaging()));
+		description.setPlatformVersion(Version.parse(springBootVersion));
+		description.setVersion(determineValue(request.getVersion(), () -> metadata.getVersion().getContent()));
+		resolvedDependencies.forEach((dependency) -> description.addDependency(dependency.getId(),
+				MetadataBuildItemMapper.toDependency(dependency)));
+	}
+
+	private String determineValue(String candidate, Supplier<String> fallback) {
+		return (StringUtils.hasText(candidate)) ? candidate : fallback.get();
+	}
+
+	private String getBaseDirectory(String baseDir, String artifactId) {
+		if (baseDir != null && baseDir.equals(artifactId)) {
+			return cleanMavenCoordinate(baseDir, "-");
+		}
+		return baseDir;
+	}
+
+	private String getName(ProjectRequest request, InitializrMetadata metadata) {
+		String name = request.getName();
+		if (!StringUtils.hasText(name)) {
+			return metadata.getName().getContent();
+		}
+		if (name.equals(request.getArtifactId())) {
+			return cleanMavenCoordinate(name, "-");
+		}
+		return name;
+	}
+
+	private String getGroupId(ProjectRequest request, InitializrMetadata metadata) {
+		if (!StringUtils.hasText(request.getGroupId())) {
+			return metadata.getGroupId().getContent();
+		}
+		return cleanMavenCoordinate(request.getGroupId(), ".");
+	}
+
+	private String getArtifactId(ProjectRequest request, InitializrMetadata metadata) {
+		if (!StringUtils.hasText(request.getArtifactId())) {
+			return metadata.getArtifactId().getContent();
+		}
+		return cleanMavenCoordinate(request.getArtifactId(), "-");
+	}
+
+	private String cleanMavenCoordinate(String coordinate, String delimiter) {
+		String[] elements = coordinate.split("[^\\w\\-.]+");
+		if (elements.length == 1) {
+			return coordinate;
+		}
+		StringBuilder builder = new StringBuilder();
+		for (String element : elements) {
+			if (shouldAppendDelimiter(element, builder)) {
+				builder.append(delimiter);
+			}
+			builder.append(element);
+		}
+		return builder.toString();
+	}
+
+	private boolean shouldAppendDelimiter(String element, StringBuilder builder) {
+		if (builder.length() == 0) {
+			return false;
+		}
+		for (char c : VALID_MAVEN_SPECIAL_CHARACTERS) {
+			int prevIndex = builder.length() - 1;
+			if (element.charAt(0) == c || builder.charAt(prevIndex) == c) {
+				return false;
+			}
+		}
+		return true;
+	}
+
+	private void validate(ProjectRequest request, InitializrMetadata metadata) {
+		validateSpringBootVersion(request);
+		validateType(request.getType(), metadata);
+		validateLanguage(request.getLanguage(), metadata);
+		validatePackaging(request.getPackaging(), metadata);
+		validateDependencies(request, metadata);
+	}
+
+	private void validateSpringBootVersion(ProjectRequest request) {
+		Version bootVersion = Version.safeParse(request.getBootVersion());
+		if (bootVersion != null && bootVersion.compareTo(VERSION_1_5_0) < 0) {
+			throw new InvalidProjectRequestException(
+					"Invalid Spring Boot version " + bootVersion + " must be 1.5.0 or higher");
+		}
+	}
+
+	private void validateType(String type, InitializrMetadata metadata) {
+		if (type != null) {
+			Type typeFromMetadata = metadata.getTypes().get(type);
+			if (typeFromMetadata == null) {
+				throw new InvalidProjectRequestException("Unknown type '" + type + "' check project metadata");
+			}
+			if (!typeFromMetadata.getTags().containsKey("build")) {
+				throw new InvalidProjectRequestException(
+						"Invalid type '" + type + "' (missing build tag) check project metadata");
+			}
+		}
+	}
+
+	private void validateLanguage(String language, InitializrMetadata metadata) {
+		if (language != null) {
+			DefaultMetadataElement languageFromMetadata = metadata.getLanguages().get(language);
+			if (languageFromMetadata == null) {
+				throw new InvalidProjectRequestException("Unknown language '" + language + "' check project metadata");
+			}
+		}
+	}
+
+	private void validatePackaging(String packaging, InitializrMetadata metadata) {
+		if (packaging != null) {
+			DefaultMetadataElement packagingFromMetadata = metadata.getPackagings().get(packaging);
+			if (packagingFromMetadata == null) {
+				throw new InvalidProjectRequestException(
+						"Unknown packaging '" + packaging + "' check project metadata");
+			}
+		}
+	}
+
+	private void validateDependencies(ProjectRequest request, InitializrMetadata metadata) {
+		List<String> dependencies = (!request.getStyle().isEmpty() ? request.getStyle() : request.getDependencies());
+		dependencies.forEach((dep) -> {
+			Dependency dependency = metadata.getDependencies().get(dep);
+			if (dependency == null) {
+				throw new InvalidProjectRequestException("Unknown dependency '" + dep + "' check project metadata");
+			}
+		});
+	}
+
+	private void validateDependencyRange(String springBootVersion, List<Dependency> resolvedDependencies) {
+		resolvedDependencies.forEach((dep) -> {
+			if (!dep.match(Version.parse(springBootVersion))) {
+				throw new InvalidProjectRequestException("Dependency '" + dep.getId() + "' is not compatible "
+						+ "with Spring Boot " + springBootVersion);
+			}
+		});
+	}
+
+	private BuildSystem getBuildSystem(ProjectRequest request, InitializrMetadata metadata) {
+		Type typeFromMetadata = metadata.getTypes().get(request.getType());
+		return BuildSystem.forId(typeFromMetadata.getTags().get("build"));
+	}
+
+	private String getPackageName(ProjectRequest request, InitializrMetadata metadata) {
+		return metadata.getConfiguration().cleanPackageName(request.getPackageName(),
+				metadata.getPackageName().getContent());
+	}
+
+	private String getApplicationName(ProjectRequest request, InitializrMetadata metadata) {
+		if (!StringUtils.hasText(request.getApplicationName())) {
+			return metadata.getConfiguration().generateApplicationName(request.getName());
+		}
+		return request.getApplicationName();
+	}
+
+	private String getSpringBootVersion(ProjectRequest request, InitializrMetadata metadata) {
+		return (request.getBootVersion() != null) ? request.getBootVersion()
+				: metadata.getBootVersions().getDefault().getId();
+	}
+
+	private List<Dependency> getResolvedDependencies(ProjectRequest request, String springBootVersion,
+			InitializrMetadata metadata) {
+		List<String> depIds = (!request.getStyle().isEmpty() ? request.getStyle() : request.getDependencies());
+		Version requestedVersion = Version.parse(springBootVersion);
+		return depIds.stream().map((it) -> {
+			Dependency dependency = metadata.getDependencies().get(it);
+			return dependency.resolve(requestedVersion);
+		}).collect(Collectors.toList());
+	}
+
+}

initializr-web/src/main/java/io/spring/initializr/web/project/ProjectGenerationInvoker.java

@@ -53,15 +53,15 @@ public class ProjectGenerationInvoker {
 
 	private final ApplicationEventPublisher eventPublisher;
 
-	private final ProjectRequestToDescriptionConverter converter;
+	private final ProjectRequestToDescriptionConverter requestConverter;
 
 	private transient Map<Path, List<Path>> temporaryFiles = new LinkedHashMap<>();
 
 	public ProjectGenerationInvoker(ApplicationContext parentApplicationContext,
-			ApplicationEventPublisher eventPublisher, ProjectRequestToDescriptionConverter converter) {
+			ApplicationEventPublisher eventPublisher, ProjectRequestToDescriptionConverter requestConverter) {
 		this.parentApplicationContext = parentApplicationContext;
 		this.eventPublisher = eventPublisher;
-		this.converter = converter;
+		this.requestConverter = requestConverter;
 	}
 
 	/**
@@ -73,7 +73,7 @@ public class ProjectGenerationInvoker {
 	public ProjectGenerationResult invokeProjectStructureGeneration(ProjectRequest request) {
 		InitializrMetadata metadata = this.parentApplicationContext.getBean(InitializrMetadataProvider.class).get();
 		try {
-			ProjectDescription description = this.converter.convert(request, metadata);
+			ProjectDescription description = this.requestConverter.convert(request, metadata);
 			ProjectGenerator projectGenerator = new ProjectGenerator((
 					projectGenerationContext) -> customizeProjectGenerationContext(projectGenerationContext, metadata));
 			ProjectGenerationResult result = projectGenerator.generate(description, generateProject(request));
@@ -104,7 +104,7 @@ public class ProjectGenerationInvoker {
 	public byte[] invokeBuildGeneration(ProjectRequest request) {
 		InitializrMetadata metadata = this.parentApplicationContext.getBean(InitializrMetadataProvider.class).get();
 		try {
-			ProjectDescription description = this.converter.convert(request, metadata);
+			ProjectDescription description = this.requestConverter.convert(request, metadata);
 			ProjectGenerator projectGenerator = new ProjectGenerator((
 					projectGenerationContext) -> customizeProjectGenerationContext(projectGenerationContext, metadata));
 			return projectGenerator.generate(description, generateBuild(request));

initializr-web/src/main/java/io/spring/initializr/web/project/ProjectRequestToDescriptionConverter.java

@@ -16,222 +16,25 @@
 
 package io.spring.initializr.web.project;
 
-import java.util.List;
-import java.util.function.Supplier;
-import java.util.stream.Collectors;
-
-import io.spring.initializr.generator.buildsystem.BuildSystem;
-import io.spring.initializr.generator.language.Language;
-import io.spring.initializr.generator.packaging.Packaging;
-import io.spring.initializr.generator.project.MutableProjectDescription;
 import io.spring.initializr.generator.project.ProjectDescription;
-import io.spring.initializr.generator.version.Version;
-import io.spring.initializr.metadata.DefaultMetadataElement;
-import io.spring.initializr.metadata.Dependency;
 import io.spring.initializr.metadata.InitializrMetadata;
-import io.spring.initializr.metadata.Type;
-import io.spring.initializr.metadata.support.MetadataBuildItemMapper;
-
-import org.springframework.util.StringUtils;
 
 /**
- * Validates a {@link ProjectRequest} and creates a {@link ProjectDescription} from it.
+ * Convert a {@link ProjectRequest} to a {@link ProjectDescription}.
  *
- * @author Madhura Bhave
- * @author HaiTao Zhang
+ * @author Stephane Nicoll
  */
-public class ProjectRequestToDescriptionConverter {
+@FunctionalInterface
+public interface ProjectRequestToDescriptionConverter {
 
-	private static final Version VERSION_1_5_0 = Version.parse("1.5.0.RELEASE");
-
-	private static final char[] VALID_MAVEN_SPECIAL_CHARACTERS = new char[] { '_', '-', '.' };
-
-	public ProjectDescription convert(ProjectRequest request, InitializrMetadata metadata) {
-		validate(request, metadata);
-		String springBootVersion = getSpringBootVersion(request, metadata);
-		List<Dependency> resolvedDependencies = getResolvedDependencies(request, springBootVersion, metadata);
-		validateDependencyRange(springBootVersion, resolvedDependencies);
-		MutableProjectDescription description = new MutableProjectDescription();
-		description.setApplicationName(getApplicationName(request, metadata));
-		description.setArtifactId(getArtifactId(request, metadata));
-		description.setBaseDirectory(getBaseDirectory(request.getBaseDir(), request.getArtifactId()));
-		description.setBuildSystem(getBuildSystem(request, metadata));
-		description
-				.setDescription(determineValue(request.getDescription(), () -> metadata.getDescription().getContent()));
-		description.setGroupId(getGroupId(request, metadata));
-		description.setLanguage(Language.forId(request.getLanguage(), request.getJavaVersion()));
-		description.setName(getName(request, metadata));
-		description.setPackageName(getPackageName(request, metadata));
-		description.setPackaging(Packaging.forId(request.getPackaging()));
-		description.setPlatformVersion(Version.parse(springBootVersion));
-		description.setVersion(determineValue(request.getVersion(), () -> metadata.getVersion().getContent()));
-		resolvedDependencies.forEach((dependency) -> description.addDependency(dependency.getId(),
-				MetadataBuildItemMapper.toDependency(dependency)));
-
-		return description;
-	}
-
-	private String determineValue(String candidate, Supplier<String> fallback) {
-		return (StringUtils.hasText(candidate)) ? candidate : fallback.get();
-	}
-
-	private String getBaseDirectory(String baseDir, String artifactId) {
-		if (baseDir != null && baseDir.equals(artifactId)) {
-			return cleanMavenCoordinate(baseDir, "-");
-		}
-		return baseDir;
-	}
-
-	private String getName(ProjectRequest request, InitializrMetadata metadata) {
-		String name = request.getName();
-		if (!StringUtils.hasText(name)) {
-			return metadata.getName().getContent();
-		}
-		if (name.equals(request.getArtifactId())) {
-			return cleanMavenCoordinate(name, "-");
-		}
-		return name;
-	}
-
-	private String getGroupId(ProjectRequest request, InitializrMetadata metadata) {
-		if (!StringUtils.hasText(request.getGroupId())) {
-			return metadata.getGroupId().getContent();
-		}
-		return cleanMavenCoordinate(request.getGroupId(), ".");
-	}
-
-	private String getArtifactId(ProjectRequest request, InitializrMetadata metadata) {
-		if (!StringUtils.hasText(request.getArtifactId())) {
-			return metadata.getArtifactId().getContent();
-		}
-		return cleanMavenCoordinate(request.getArtifactId(), "-");
-	}
-
-	private String cleanMavenCoordinate(String coordinate, String delimiter) {
-		String[] elements = coordinate.split("[^\\w\\-.]+");
-		if (elements.length == 1) {
-			return coordinate;
-		}
-		StringBuilder builder = new StringBuilder();
-		for (String element : elements) {
-			if (shouldAppendDelimiter(element, builder)) {
-				builder.append(delimiter);
-			}
-			builder.append(element);
-		}
-		return builder.toString();
-	}
-
-	private boolean shouldAppendDelimiter(String element, StringBuilder builder) {
-		if (builder.length() == 0) {
-			return false;
-		}
-		for (char c : VALID_MAVEN_SPECIAL_CHARACTERS) {
-			int prevIndex = builder.length() - 1;
-			if (element.charAt(0) == c || builder.charAt(prevIndex) == c) {
-				return false;
-			}
-		}
-		return true;
-	}
-
-	private void validate(ProjectRequest request, InitializrMetadata metadata) {
-		validateSpringBootVersion(request);
-		validateType(request.getType(), metadata);
-		validateLanguage(request.getLanguage(), metadata);
-		validatePackaging(request.getPackaging(), metadata);
-		validateDependencies(request, metadata);
-	}
-
-	private void validateSpringBootVersion(ProjectRequest request) {
-		Version bootVersion = Version.safeParse(request.getBootVersion());
-		if (bootVersion != null && bootVersion.compareTo(VERSION_1_5_0) < 0) {
-			throw new InvalidProjectRequestException(
-					"Invalid Spring Boot version " + bootVersion + " must be 1.5.0 or higher");
-		}
-	}
-
-	private void validateType(String type, InitializrMetadata metadata) {
-		if (type != null) {
-			Type typeFromMetadata = metadata.getTypes().get(type);
-			if (typeFromMetadata == null) {
-				throw new InvalidProjectRequestException("Unknown type '" + type + "' check project metadata");
-			}
-			if (!typeFromMetadata.getTags().containsKey("build")) {
-				throw new InvalidProjectRequestException(
-						"Invalid type '" + type + "' (missing build tag) check project metadata");
-			}
-		}
-	}
-
-	private void validateLanguage(String language, InitializrMetadata metadata) {
-		if (language != null) {
-			DefaultMetadataElement languageFromMetadata = metadata.getLanguages().get(language);
-			if (languageFromMetadata == null) {
-				throw new InvalidProjectRequestException("Unknown language '" + language + "' check project metadata");
-			}
-		}
-	}
-
-	private void validatePackaging(String packaging, InitializrMetadata metadata) {
-		if (packaging != null) {
-			DefaultMetadataElement packagingFromMetadata = metadata.getPackagings().get(packaging);
-			if (packagingFromMetadata == null) {
-				throw new InvalidProjectRequestException(
-						"Unknown packaging '" + packaging + "' check project metadata");
-			}
-		}
-	}
-
-	private void validateDependencies(ProjectRequest request, InitializrMetadata metadata) {
-		List<String> dependencies = (!request.getStyle().isEmpty() ? request.getStyle() : request.getDependencies());
-		dependencies.forEach((dep) -> {
-			Dependency dependency = metadata.getDependencies().get(dep);
-			if (dependency == null) {
-				throw new InvalidProjectRequestException("Unknown dependency '" + dep + "' check project metadata");
-			}
-		});
-	}
-
-	private void validateDependencyRange(String springBootVersion, List<Dependency> resolvedDependencies) {
-		resolvedDependencies.forEach((dep) -> {
-			if (!dep.match(Version.parse(springBootVersion))) {
-				throw new InvalidProjectRequestException("Dependency '" + dep.getId() + "' is not compatible "
-						+ "with Spring Boot " + springBootVersion);
-			}
-		});
-	}
-
-	private BuildSystem getBuildSystem(ProjectRequest request, InitializrMetadata metadata) {
-		Type typeFromMetadata = metadata.getTypes().get(request.getType());
-		return BuildSystem.forId(typeFromMetadata.getTags().get("build"));
-	}
-
-	private String getPackageName(ProjectRequest request, InitializrMetadata metadata) {
-		return metadata.getConfiguration().cleanPackageName(request.getPackageName(),
-				metadata.getPackageName().getContent());
-	}
-
-	private String getApplicationName(ProjectRequest request, InitializrMetadata metadata) {
-		if (!StringUtils.hasText(request.getApplicationName())) {
-			return metadata.getConfiguration().generateApplicationName(request.getName());
-		}
-		return request.getApplicationName();
-	}
-
-	private String getSpringBootVersion(ProjectRequest request, InitializrMetadata metadata) {
-		return (request.getBootVersion() != null) ? request.getBootVersion()
-				: metadata.getBootVersions().getDefault().getId();
-	}
-
-	private List<Dependency> getResolvedDependencies(ProjectRequest request, String springBootVersion,
-			InitializrMetadata metadata) {
-		List<String> depIds = (!request.getStyle().isEmpty() ? request.getStyle() : request.getDependencies());
-		Version requestedVersion = Version.parse(springBootVersion);
-		return depIds.stream().map((it) -> {
-			Dependency dependency = metadata.getDependencies().get(it);
-			return dependency.resolve(requestedVersion);
-		}).collect(Collectors.toList());
-	}
+	/**
+	 * Validate and convert the specified {@link ProjectRequest} to a
+	 * {@link ProjectDescription} used as the source of project generation.
+	 * @param request the request to convert
+	 * @param metadata the metadata instance to use
+	 * @return a validated {@link ProjectDescription} to use to generate a project that
+	 * matches the specified {@code request}
+	 */
+	ProjectDescription convert(ProjectRequest request, InitializrMetadata metadata);
 
 }

initializr-web/src/test/java/io/spring/initializr/web/autoconfigure/InitializrAutoConfigurationTests.java

@@ -28,15 +28,12 @@ import io.spring.initializr.web.project.ProjectRequestToDescriptionConverter;
 import io.spring.initializr.web.support.DefaultInitializrMetadataUpdateStrategy;
 import io.spring.initializr.web.support.InitializrMetadataUpdateStrategy;
 import org.junit.jupiter.api.Test;
-import org.mockito.Mockito;
 
 import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.cache.JCacheManagerCustomizer;
-import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration;
 import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration;
 import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
@@ -57,9 +54,11 @@ import static org.mockito.Mockito.mock;
  */
 class InitializrAutoConfigurationTests {
 
+	private static final AutoConfigurations BASIC_AUTO_CONFIGURATIONS = AutoConfigurations
+			.of(RestTemplateAutoConfiguration.class, JacksonAutoConfiguration.class, InitializrAutoConfiguration.class);
+
 	private ApplicationContextRunner contextRunner = new ApplicationContextRunner()
-			.withConfiguration(AutoConfigurations.of(RestTemplateAutoConfiguration.class,
-					JacksonAutoConfiguration.class, InitializrAutoConfiguration.class));
+			.withConfiguration(BASIC_AUTO_CONFIGURATIONS);
 
 	@Test
 	void autoConfigRegistersTemplateRenderer() {
@@ -127,13 +126,10 @@ class InitializrAutoConfigurationTests {
 	@Test
 	void webConfiguration() {
 		WebApplicationContextRunner webContextRunner = new WebApplicationContextRunner()
-				.withConfiguration(AutoConfigurations.of(RestTemplateAutoConfiguration.class,
-						JacksonAutoConfiguration.class, HttpMessageConvertersAutoConfiguration.class,
-						WebMvcAutoConfiguration.class, InitializrAutoConfiguration.class));
+				.withConfiguration(BASIC_AUTO_CONFIGURATIONS);
 		webContextRunner.run((context) -> {
 			assertThat(context).hasSingleBean(InitializrWebConfig.class);
 			assertThat(context).hasSingleBean(ProjectGenerationInvoker.class);
-			assertThat(context).hasSingleBean(ProjectRequestToDescriptionConverter.class);
 			assertThat(context).hasSingleBean(ProjectGenerationController.class);
 			assertThat(context).hasSingleBean(ProjectMetadataController.class);
 			assertThat(context).hasSingleBean(CommandLineMetadataController.class);
@@ -141,6 +137,17 @@ class InitializrAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void autoConfigWithCustomProjectRequestConverter() {
+		new WebApplicationContextRunner().withConfiguration(BASIC_AUTO_CONFIGURATIONS)
+				.withUserConfiguration(CustomProjectRequestToDescriptionConverter.class).run((context) -> {
+					assertThat(context).hasSingleBean(ProjectGenerationInvoker.class);
+					assertThat(context.getBean(ProjectGenerationInvoker.class)).hasFieldOrPropertyWithValue(
+							"requestConverter", context.getBean("testProjectRequestToDescriptionConverter"));
+				});
+
+	}
+
 	@Test
 	void webConfigurationConditionalOnWebApplication() {
 		this.contextRunner.run((context) -> {
@@ -180,7 +187,7 @@ class InitializrAutoConfigurationTests {
 
 		@Bean
 		TemplateRenderer testTemplateRenderer() {
-			return Mockito.mock(TemplateRenderer.class);
+			return mock(TemplateRenderer.class);
 		}
 
 	}
@@ -190,7 +197,7 @@ class InitializrAutoConfigurationTests {
 
 		@Bean
 		InitializrMetadataUpdateStrategy testInitializrMetadataUpdateStrategy() {
-			return Mockito.mock(InitializrMetadataUpdateStrategy.class);
+			return mock(InitializrMetadataUpdateStrategy.class);
 		}
 
 	}
@@ -200,7 +207,7 @@ class InitializrAutoConfigurationTests {
 
 		@Bean
 		InitializrMetadataProvider testInitializrMetadataProvider() {
-			return Mockito.mock(InitializrMetadataProvider.class);
+			return mock(InitializrMetadataProvider.class);
 		}
 
 	}
@@ -210,7 +217,17 @@ class InitializrAutoConfigurationTests {
 
 		@Bean
 		DependencyMetadataProvider testDependencyMetadataProvider() {
-			return Mockito.mock(DependencyMetadataProvider.class);
+			return mock(DependencyMetadataProvider.class);
+		}
+
+	}
+
+	@Configuration
+	static class CustomProjectRequestToDescriptionConverter {
+
+		@Bean
+		ProjectRequestToDescriptionConverter testProjectRequestToDescriptionConverter() {
+			return mock(ProjectRequestToDescriptionConverter.class);
 		}
 
 	}

initializr-web/src/test/java/io/spring/initializr/web/controller/custom/CustomProjectContributor.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.web.controller.custom;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import io.spring.initializr.generator.project.ProjectDescription;
+import io.spring.initializr.generator.project.contributor.ProjectContributor;
+
+/**
+ * A {@link ProjectContributor} that adds an {@code custom.txt} file at the root of the
+ * project when the registered description is a {@link CustomProjectDescription} and its
+ * {@code customFlag} is {@code enabled}.
+ *
+ * @author Stephane Nicoll
+ */
+class CustomProjectContributor implements ProjectContributor {
+
+	private final ProjectDescription description;
+
+	CustomProjectContributor(ProjectDescription description) {
+		this.description = description;
+	}
+
+	@Override
+	public void contribute(Path projectRoot) throws IOException {
+		if (this.description instanceof CustomProjectDescription
+				&& ((CustomProjectDescription) this.description).isCustomFlag()) {
+			Files.createFile(projectRoot.resolve("custom.txt"));
+		}
+	}
+
+}

initializr-web/src/test/java/io/spring/initializr/web/controller/custom/CustomProjectDescription.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.web.controller.custom;
+
+import io.spring.initializr.generator.project.MutableProjectDescription;
+import io.spring.initializr.generator.project.ProjectDescription;
+
+/**
+ * A custom {@link ProjectDescription} to convey the additional flags to contributors.
+ *
+ * @author Stephane Nicoll
+ */
+class CustomProjectDescription extends MutableProjectDescription {
+
+	private boolean customFlag;
+
+	boolean isCustomFlag() {
+		return this.customFlag;
+	}
+
+	void setCustomFlag(boolean customFlag) {
+		this.customFlag = customFlag;
+	}
+
+}

initializr-web/src/test/java/io/spring/initializr/web/controller/custom/CustomProjectGenerationController.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.web.controller.custom;
+
+import java.util.Map;
+
+import io.spring.initializr.metadata.InitializrMetadataProvider;
+import io.spring.initializr.web.controller.ProjectGenerationController;
+import io.spring.initializr.web.project.ProjectGenerationInvoker;
+
+/**
+ * A custom {@link ProjectGenerationController} that binds request attributes to a
+ * {@link CustomProjectRequest}.
+ *
+ * @author Stephane Nicoll
+ */
+class CustomProjectGenerationController extends ProjectGenerationController<CustomProjectRequest> {
+
+	CustomProjectGenerationController(InitializrMetadataProvider metadataProvider,
+			ProjectGenerationInvoker projectGenerationInvoker) {
+		super(metadataProvider, projectGenerationInvoker);
+	}
+
+	@Override
+	public CustomProjectRequest projectRequest(Map<String, String> headers) {
+		CustomProjectRequest request = new CustomProjectRequest();
+		request.getParameters().putAll(headers);
+		request.initialize(getMetadata());
+		return request;
+	}
+
+}

initializr-web/src/test/java/io/spring/initializr/web/controller/custom/CustomProjectRequest.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.web.controller.custom;
+
+import io.spring.initializr.web.project.ProjectRequest;
+import io.spring.initializr.web.project.WebProjectRequest;
+
+/**
+ * A custom {@link ProjectRequest} with an additional custom boolean flag. This type has
+ * to be public for the {@code customFlag} request attribute to be mapped properly.
+ *
+ * @author Stephane Nicoll
+ */
+public class CustomProjectRequest extends WebProjectRequest {
+
+	private boolean customFlag;
+
+	public boolean isCustomFlag() {
+		return this.customFlag;
+	}
+
+	public void setCustomFlag(boolean customFlag) {
+		this.customFlag = customFlag;
+	}
+
+}

initializr-web/src/test/java/io/spring/initializr/web/controller/custom/ProjectGenerationControllerCustomRequestIntegrationTests.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.web.controller.custom;
+
+import io.spring.initializr.generator.project.ProjectDescription;
+import io.spring.initializr.generator.test.project.ProjectStructure;
+import io.spring.initializr.metadata.InitializrMetadata;
+import io.spring.initializr.metadata.InitializrMetadataProvider;
+import io.spring.initializr.web.AbstractInitializrControllerIntegrationTests;
+import io.spring.initializr.web.controller.ProjectGenerationController;
+import io.spring.initializr.web.controller.custom.ProjectGenerationControllerCustomRequestIntegrationTests.CustomProjectGenerationConfiguration;
+import io.spring.initializr.web.project.DefaultProjectRequestToDescriptionConverter;
+import io.spring.initializr.web.project.ProjectGenerationInvoker;
+import io.spring.initializr.web.project.ProjectRequest;
+import io.spring.initializr.web.project.ProjectRequestToDescriptionConverter;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.context.ActiveProfiles;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for a {@link ProjectGenerationController} that maps to a custom
+ * request.
+ *
+ * @author Stephane Nicoll
+ */
+@ActiveProfiles("test-default")
+@Import(CustomProjectGenerationConfiguration.class)
+public class ProjectGenerationControllerCustomRequestIntegrationTests
+		extends AbstractInitializrControllerIntegrationTests {
+
+	@Test
+	void createProjectWithCustomFlagEnabled() {
+		ProjectStructure project = downloadZip("/starter.zip?dependencies=web&customFlag=true");
+		assertThat(project).containsFiles("custom.txt");
+	}
+
+	@Test
+	void createProjectWithCustomFlagDisabled() {
+		ProjectStructure project = downloadZip("/starter.zip?dependencies=web&customFlag=false");
+		assertThat(project).doesNotContainFiles("custom.txt");
+	}
+
+	@Test
+	void createProjectWithOverriddenRequestParams() {
+		ProjectStructure project = downloadZip("/starter.zip?groupId=com.acme&artifactId=test");
+		assertThat(project).containsFiles("src/main/java/org/example/custom/CustomApp.java",
+				"src/test/java/org/example/custom/CustomAppTests.java");
+		assertThat(project).doesNotContainDirectories("src/main/java/com", "src/test/java/com");
+		assertThat(project).doesNotContainFiles("custom.txt");
+	}
+
+	@Configuration
+	static class CustomProjectGenerationConfiguration {
+
+		@Bean
+		CustomProjectGenerationController customProjectGenerationController(InitializrMetadataProvider metadataProvider,
+				ProjectGenerationInvoker projectGenerationInvoker) {
+			return new CustomProjectGenerationController(metadataProvider, projectGenerationInvoker);
+		}
+
+		@Bean
+		ProjectRequestToDescriptionConverter customProjectRequestToDescriptionConverter() {
+			return new CustomProjectRequestToDescriptionConverter();
+		}
+
+	}
+
+	static class CustomProjectRequestToDescriptionConverter implements ProjectRequestToDescriptionConverter {
+
+		@Override
+		public ProjectDescription convert(ProjectRequest request, InitializrMetadata metadata) {
+			CustomProjectRequest customRequest = (CustomProjectRequest) request;
+			CustomProjectDescription description = new CustomProjectDescription();
+			new DefaultProjectRequestToDescriptionConverter().convert(request, description, metadata);
+			description.setCustomFlag(customRequest.isCustomFlag());
+			// Override attributes for test purposes
+			description.setPackageName("org.example.custom");
+			description.setApplicationName("CustomApp");
+			return description;
+		}
+
+	}
+
+}

initializr-web/src/test/java/io/spring/initializr/web/project/DefaultProjectRequestToDescriptionConverterTests.java

@@ -32,17 +32,17 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 /**
- * Tests for {@link ProjectRequestToDescriptionConverter}.
+ * Tests for {@link DefaultProjectRequestToDescriptionConverter}.
  *
  * @author Madhura Bhave
  * @author Stephane Nicoll
  * @author HaiTao Zhang
  */
-class ProjectRequestToDescriptionConverterTests {
+class DefaultProjectRequestToDescriptionConverterTests {
 
 	private InitializrMetadata metadata = InitializrMetadataTestBuilder.withDefaults().build();
 
-	private final ProjectRequestToDescriptionConverter converter = new ProjectRequestToDescriptionConverter();
+	private final DefaultProjectRequestToDescriptionConverter converter = new DefaultProjectRequestToDescriptionConverter();
 
 	@Test
 	void convertWhenTypeIsInvalidShouldThrowException() {

initializr-web/src/test/java/io/spring/initializr/web/project/ProjectGenerationInvokerTests.java

@@ -69,8 +69,8 @@ public class ProjectGenerationInvokerTests {
 	@BeforeEach
 	void setup() {
 		setupContext();
-		ProjectRequestToDescriptionConverter converter = new ProjectRequestToDescriptionConverter();
-		this.invoker = new ProjectGenerationInvoker(this.context, this.eventPublisher, converter);
+		this.invoker = new ProjectGenerationInvoker(this.context, this.eventPublisher,
+				new DefaultProjectRequestToDescriptionConverter());
 	}
 
 	@AfterEach

initializr-web/src/test/resources/META-INF/spring.factories

@@ -0,0 +1 @@
+io.spring.initializr.generator.project.ProjectGenerationConfiguration=io.spring.initializr.web.controller.custom.CustomProjectContributor