make current with latest changes in 'spring-graphql'

issue spring-projects#3501

Author: dmfrey

Diff for: spring-integration-graphql/src/main/java/org/springframework/integration/graphql/outbound/GraphQlMessageHandler.java

@@ -0,0 +1,170 @@
+/*
+ * Copyright 2021-2022 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 org.springframework.integration.graphql.outbound;
+
+import java.util.Collections;
+import java.util.Locale;
+import java.util.Map;
+
+import javax.annotation.Nullable;
+
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.expression.Expression;
+import org.springframework.expression.common.LiteralExpression;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.graphql.GraphQlService;
+import org.springframework.graphql.RequestInput;
+import org.springframework.integration.expression.ExpressionUtils;
+import org.springframework.integration.expression.SupplierExpression;
+import org.springframework.integration.handler.AbstractReplyProducingMessageHandler;
+import org.springframework.messaging.Message;
+import org.springframework.util.Assert;
+
+/**
+ * A {@link org.springframework.messaging.MessageHandler} capable of fielding GraphQL Query, Mutation and Subscription requests.
+ *
+ * @author Daniel Frey
+ * @since 6.0
+ */
+public class GraphQlMessageHandler extends AbstractReplyProducingMessageHandler {
+
+	private final GraphQlService graphQlService;
+
+	private StandardEvaluationContext evaluationContext;
+
+	private Expression queryExpression;
+
+	private Expression operationNameExpression = new SupplierExpression<>(() -> null);
+
+	private Expression variablesExpression = new SupplierExpression<>(() -> Collections.emptyMap());
+
+	private Locale locale = null;
+
+	private String executionId = null;
+
+	public GraphQlMessageHandler(final GraphQlService graphQlService) {
+		Assert.notNull(graphQlService, "'graphQlService' must not be null");
+
+		this.graphQlService = graphQlService;
+		setAsync(true);
+	}
+
+	/**
+	 * Specify a GraphQL Query.
+	 * @param query the GraphQL query to use.
+	 */
+	public void setQuery(String query) {
+		Assert.hasText(query, "'query' must not be empty");
+		setQueryExpression(new LiteralExpression(query));
+	}
+
+	/**
+	 * Specify a SpEL expression to evaluate a GraphQL Query
+	 * @param queryExpression the expression to evaluate a GraphQL query.
+	 */
+	public void setQueryExpression(Expression queryExpression) {
+		Assert.notNull(queryExpression, "'queryExpression' must not be null");
+		this.queryExpression = queryExpression;
+	}
+
+	/**
+	 * Set a GraphQL Operation Name to execute.
+	 * @param operationName the GraphQL Operation Name to use.
+	 */
+	public void setOperationName(String operationName) {
+		setOperationNameExpression(new LiteralExpression(operationName));
+	}
+
+	/**
+	 * Set a SpEL expression to evaluate a GraphQL Operation Name to execute.
+	 * @param operationNameExpression the expression to use.
+	 */
+	public void setOperationNameExpression(Expression operationNameExpression) {
+		Assert.notNull(operationNameExpression, "'operationNameExpression' must not be null");
+		this.operationNameExpression = operationNameExpression;
+	}
+
+	/**
+	 * Set a SpEL expression to evaluate Variables for GraphQL Query to execute.
+	 * @param variablesExpression the expression to use.
+	 */
+	public void setVariablesExpression(Expression variablesExpression) {
+		Assert.notNull(variablesExpression, "'variablesExpression' must not be null");
+		this.variablesExpression = variablesExpression;
+	}
+
+	/**
+	 * Set a Locale for GraphQL Query to execute.
+	 * @param locale the locale to use.
+	 */
+	public void setLocale(@Nullable Locale locale) {
+		this.locale = locale;
+	}
+
+	/**
+	 * Set a Execution Id for GraphQL Query to execute.
+	 * @param executionId the executionId to use.
+	 */
+	public void setExecutionId(String executionId) {
+		Assert.hasText(executionId, "'executionId' must not be empty");
+		this.executionId = executionId;
+	}
+
+	@Override
+	protected final void doInit() {
+		BeanFactory beanFactory = getBeanFactory();
+		this.evaluationContext = ExpressionUtils.createStandardEvaluationContext(beanFactory);
+	}
+
+	@Override
+	protected Object handleRequestMessage(Message<?> requestMessage) {
+		RequestInput requestInput = null;
+
+		if (requestMessage.getPayload() instanceof RequestInput) {
+
+			requestInput = (RequestInput) requestMessage.getPayload();
+		}
+		else  {
+			Assert.notNull(this.queryExpression, "'queryExpression' must not be null");
+			Assert.hasText(this.executionId, "'executionId' must not be empty");
+			String query = evaluateQueryExpression(requestMessage);
+			String operationName = evaluateOperationNameExpression(requestMessage);
+			Map<String, Object> variables = evaluateVariablesExpression(requestMessage);
+			requestInput = new RequestInput(query, operationName, variables, this.locale, this.executionId);
+		}
+
+		return this.graphQlService
+				.execute(requestInput);
+
+	}
+
+	private String evaluateQueryExpression(Message<?> message) {
+		String query = this.queryExpression.getValue(this.evaluationContext, message, String.class);
+		Assert.notNull(query, "'queryExpression' must not evaluate to null");
+		return query;
+	}
+
+	private String evaluateOperationNameExpression(Message<?> message) {
+		return this.operationNameExpression.getValue(this.evaluationContext, message, String.class);
+	}
+
+	@SuppressWarnings("unchecked")
+	private Map<String, Object> evaluateVariablesExpression(Message<?> message) {
+		return this.variablesExpression.getValue(this.evaluationContext, message, Map.class);
+	}
+
+}