Allow arguments to be used without creating a field.

See #3265

Author: christophstrobl

src/main/java/org/springframework/data/repository/aot/generate/AotRepositoryBuilder.java

@@ -19,6 +19,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.BiFunction;
@@ -29,10 +30,10 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.jspecify.annotations.Nullable;
-
 import org.springframework.aot.generate.ClassNameGenerator;
 import org.springframework.aot.generate.Generated;
 import org.springframework.data.projection.ProjectionFactory;
+import org.springframework.data.repository.aot.generate.AotRepositoryFragmentMetadata.ConstructorArgument;
 import org.springframework.data.repository.aot.generate.json.JSONException;
 import org.springframework.data.repository.aot.generate.json.JSONObject;
 import org.springframework.data.repository.core.RepositoryInformation;
@@ -215,7 +216,11 @@ private String typeName() {
 	}
 
 	public Map<String, TypeName> getAutowireFields() {
-		return generationMetadata.getConstructorArguments();
+		Map<String, TypeName> autowireFields = new LinkedHashMap<>(generationMetadata.getConstructorArguments().size());
+		for (Map.Entry<String, ConstructorArgument> entry : generationMetadata.getConstructorArguments().entrySet()) {
+			autowireFields.put(entry.getKey(), entry.getValue().getTypeName());
+		}
+		return autowireFields;
 	}
 
 	public RepositoryInformation getRepositoryInformation() {
@@ -238,8 +243,7 @@ public interface ClassCustomizer {
 		 * @param metadata
 		 * @param builder
 		 */
-		void customize(RepositoryInformation information, AotRepositoryFragmentMetadata metadata,
-				TypeSpec.Builder builder);
+		void customize(RepositoryInformation information, AotRepositoryFragmentMetadata metadata, TypeSpec.Builder builder);
 
 	}
 

src/main/java/org/springframework/data/repository/aot/generate/AotRepositoryConstructorBuilder.java

@@ -21,6 +21,7 @@
 import javax.lang.model.element.Modifier;
 
 import org.springframework.core.ResolvableType;
+import org.springframework.data.repository.aot.generate.AotRepositoryFragmentMetadata.ConstructorArgument;
 import org.springframework.data.repository.core.RepositoryInformation;
 import org.springframework.javapoet.MethodSpec;
 import org.springframework.javapoet.ParameterizedTypeName;
@@ -64,15 +65,27 @@ public void addParameter(String parameterName, Class<?> type) {
 	}
 
 	/**
-	 * Add constructor parameter.
+	 * Add constructor parameter and create a field for it.
 	 *
 	 * @param parameterName
 	 * @param type
 	 */
 	public void addParameter(String parameterName, TypeName type) {
+		addParameter(parameterName, type, true);
+	}
 
-		this.metadata.addConstructorArgument(parameterName, type);
-		this.metadata.addField(parameterName, type, Modifier.PRIVATE, Modifier.FINAL);
+	/**
+	 * Add constructor parameter.
+	 *
+	 * @param parameterName
+	 * @param type
+	 */
+	public void addParameter(String parameterName, TypeName type, boolean createField) {
+
+		this.metadata.addConstructorArgument(parameterName, type, createField ? parameterName : null);
+		if(createField) {
+			this.metadata.addField(parameterName, type, Modifier.PRIVATE, Modifier.FINAL);
+		}
 	}
 
 	/**
@@ -89,15 +102,17 @@ MethodSpec buildConstructor() {
 
 		MethodSpec.Builder builder = MethodSpec.constructorBuilder().addModifiers(Modifier.PUBLIC);
 
-		for (Entry<String, TypeName> parameter : this.metadata.getConstructorArguments().entrySet()) {
-			builder.addParameter(parameter.getValue(), parameter.getKey());
+		for (Entry<String, ConstructorArgument> parameter : this.metadata.getConstructorArguments().entrySet()) {
+			builder.addParameter(parameter.getValue().getTypeName(), parameter.getKey());
 		}
 
 		customizer.customize(repositoryInformation, builder);
 
-		for (Entry<String, TypeName> parameter : this.metadata.getConstructorArguments().entrySet()) {
-			builder.addStatement("this.$N = $N", parameter.getKey(),
+		for (Entry<String, ConstructorArgument> parameter : this.metadata.getConstructorArguments().entrySet()) {
+			if(parameter.getValue().isForLocalField()) {
+				builder.addStatement("this.$N = $N", parameter.getKey(),
 					parameter.getKey());
+			}
 		}
 
 		return builder.build();

src/main/java/org/springframework/data/repository/aot/generate/AotRepositoryFragmentMetadata.java

@@ -35,7 +35,7 @@ public class AotRepositoryFragmentMetadata {
 
 	private final ClassName className;
 	private final Map<String, FieldSpec> fields = new HashMap<>(3);
-	private final Map<String, TypeName> constructorArguments = new LinkedHashMap<>(3);
+	private final Map<String, ConstructorArgument> constructorArguments = new LinkedHashMap<>(3);
 
 	public AotRepositoryFragmentMetadata(ClassName className) {
 		this.className = className;
@@ -82,11 +82,43 @@ Map<String, FieldSpec> getFields() {
 		return fields;
 	}
 
-	public Map<String, TypeName> getConstructorArguments() {
+	public Map<String, ConstructorArgument> getConstructorArguments() {
 		return constructorArguments;
 	}
 
 	public void addConstructorArgument(String parameterName, TypeName type) {
-		this.constructorArguments.put(parameterName, type);
+		addConstructorArgument(parameterName, type, parameterName);
+	}
+
+	public void addConstructorArgument(String parameterName, TypeName type, @Nullable String fieldName) {
+		this.constructorArguments.put(parameterName, new ConstructorArgument(parameterName, type, fieldName));
+	}
+
+	static class ConstructorArgument {
+		String parameterName;
+		@Nullable String fieldName;
+		TypeName typeName;
+
+		public ConstructorArgument(String parameterName,TypeName typeName, String fieldName) {
+			this.parameterName = parameterName;
+			this.fieldName = fieldName;
+			this.typeName = typeName;
+		}
+
+		boolean isForLocalField() {
+			return fieldName != null;
+		}
+
+		public String getParameterName() {
+			return parameterName;
+		}
+
+		public String getFieldName() {
+			return fieldName;
+		}
+
+		public TypeName getTypeName() {
+			return typeName;
+		}
 	}
 }