Allow creation of custom GraphQlSource instance

Closes gh-1086

spring-graphql/src/main/java/org/springframework/graphql/execution/AbstractGraphQlSourceBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -32,6 +32,7 @@ import graphql.schema.SchemaTransformer;
 import graphql.schema.SchemaTraverser;
 
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 
 /**
@@ -58,6 +59,8 @@ public abstract class AbstractGraphQlSourceBuilder<B extends GraphQlSource.Build
 	@Nullable
 	private Consumer<GraphQL.Builder> graphQlConfigurer;
 
+	private GraphQlSource.Factory graphQlSourceFactory = FixedGraphQlSource::new;
+
 
 	@Override
 	public B exceptionResolvers(List<DataFetcherExceptionResolver> resolvers) {
@@ -96,6 +99,13 @@ public abstract class AbstractGraphQlSourceBuilder<B extends GraphQlSource.Build
 		return self();
 	}
 
+	@Override
+	public B graphQlSourceFactory(GraphQlSource.Factory factory) {
+		Assert.notNull(factory, "GraphQlSource.Factory is required");
+		this.graphQlSourceFactory = factory;
+		return self();
+	}
+
 	@SuppressWarnings("unchecked")
 	private  <T extends B> T self() {
 		return (T) this;
@@ -118,7 +128,7 @@ public abstract class AbstractGraphQlSourceBuilder<B extends GraphQlSource.Build
 
 		applyGraphQlConfigurers(builder);
 
-		return new FixedGraphQlSource(builder.build(), schema);
+		return this.graphQlSourceFactory.create(builder.build(), schema);
 	}
 
 	/**

spring-graphql/src/main/java/org/springframework/graphql/execution/GraphQlSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -149,6 +149,18 @@ public interface GraphQlSource {
 		 */
 		B configureGraphQl(Consumer<GraphQL.Builder> configurer);
 
+		/**
+		 * Configure a factory to use to create the {@link GraphQlSource} instance
+		 * to return from the {@link #build()} method.
+		 * <p>By default, the instance is a simple container of {@link GraphQL} and
+		 * {@link GraphQLSchema}. Applications can use this to create a different
+		 * implementation that applies additional per-request logic.
+		 * @param factory the factory to use
+		 * @return the current builder
+		 * @since 1.4.0
+		 */
+		B graphQlSourceFactory(Factory factory);
+
 		/**
 		 * Build the {@link GraphQlSource} instance.
 		 */
@@ -240,4 +252,19 @@ public interface GraphQlSource {
 
 	}
 
+
+	/**
+	 * Strategy to create the {@link GraphQlSource} instance in {@link Builder#build()}.
+	 */
+	interface Factory {
+
+		/**
+		 * Create a {@link GraphQlSource} with the given inputs.
+		 * @param graphQl the {@code GraphQLJava} initialized by the builder
+		 * @param schema the schema initialized by the builder
+		 * @return the created instance
+		 */
+		GraphQlSource create(GraphQL graphQl, GraphQLSchema schema);
+	}
+
 }