Create web stack-specific GraphQL handlers

Instead of trying to create a single handler for both reactive and
non-reactive implementations, this commit splits the implementations.

spring-graphql-web/src/main/java/org/springframework/graphql/GraphQLHandler.java

@@ -1,57 +0,0 @@
-package org.springframework.graphql;
-
-import graphql.ExecutionInput;
-import graphql.ExecutionResult;
-import graphql.GraphQL;
-import org.springframework.http.HttpHeaders;
-import org.springframework.util.MultiValueMap;
-import reactor.core.publisher.Mono;
-
-import java.util.List;
-import java.util.Map;
-
-public class GraphQLHandler {
-    private GraphQL graphQL;
-
-    private GraphQLInterceptor interceptor;
-
-    public GraphQLHandler(GraphQL graphQL, GraphQLInterceptor interceptor) {
-        this.graphQL = graphQL;
-        this.interceptor = interceptor;
-    }
-
-    public Mono<GraphQLHttpResponse> graphqlPOST(GraphQLHttpRequest graphQLHttpRequest) {
-        String query = graphQLHttpRequest.getQuery();
-        ExecutionInput input = ExecutionInput.newExecutionInput()
-                .query(query)
-                .operationName(graphQLHttpRequest.getOperationName())
-                .variables(graphQLHttpRequest.getVariables())
-                .build();
-        MultiValueMap<String, String> requestParams = graphQLHttpRequest.getRequestParams();
-        Mono<ExecutionInput> executionInput = interceptor.preHandle(input,
-                graphQLHttpRequest.getHttpHeaders(),
-                requestParams);
-        return executionInput
-                .flatMap(this::execute)
-                .flatMap(result -> interceptor.postHandle(result, graphQLHttpRequest.getHttpHeaders(), requestParams))
-                .flatMap(result -> toResponseBody(result, graphQLHttpRequest));
-    }
-
-    private Mono<GraphQLHttpResponse> toResponseBody(ExecutionResult executionResult, GraphQLHttpRequest graphQLHttpRequest) {
-        Map<String, Object> responseBodyRaw = executionResult.toSpecification();
-        Object data = responseBodyRaw.get("data");
-        List<Map<String, Object>> errors = (List<Map<String, Object>>) responseBodyRaw.get("errors");
-        Map<String, Object> extensions = (Map<String, Object>) responseBodyRaw.get("extensions");
-        GraphQLHttpResponse responseBody = new GraphQLHttpResponse(data,
-                errors,
-                extensions,
-                new HttpHeaders());
-        Mono<GraphQLHttpResponse> graphQLResponseBodyMono = interceptor.customizeGraphQLHttpResponse(responseBody, executionResult, graphQLHttpRequest);
-        return graphQLResponseBodyMono;
-    }
-
-
-    protected Mono<ExecutionResult> execute(ExecutionInput input) {
-        return Mono.fromCompletionStage(graphQL.executeAsync(input));
-    }
-}

spring-graphql-web/src/main/java/org/springframework/graphql/reactive/GraphQLHandler.java

@@ -0,0 +1,52 @@
+package org.springframework.graphql.reactive;
+
+import graphql.ExecutionInput;
+import graphql.ExecutionResult;
+import graphql.GraphQL;
+import reactor.core.publisher.Mono;
+
+import org.springframework.graphql.GraphQLRequestBody;
+import org.springframework.http.HttpHeaders;
+import org.springframework.web.reactive.function.server.ServerRequest;
+import org.springframework.web.reactive.function.server.ServerResponse;
+
+public class GraphQLHandler {
+
+	private final GraphQL graphQL;
+
+	public GraphQLHandler(GraphQL.Builder graphQLBuilder) {
+		this.graphQL = graphQLBuilder.build();
+	}
+
+	public Mono<ServerResponse> handle(ServerRequest request) {
+		Mono<GraphQLRequestBody> bodyMono = request.bodyToMono(GraphQLRequestBody.class);
+		return bodyMono.map(body -> {
+			String query = body.getQuery();
+			if (query == null) {
+				query = "";
+			}
+			ExecutionInput executionInput = ExecutionInput.newExecutionInput()
+					.query(query)
+					.operationName(body.getOperationName())
+					.variables(body.getVariables())
+					.build();
+			return customizeExecutionInput(executionInput, request.headers().asHttpHeaders())
+					.then(execute(executionInput));
+		})
+				.flatMap(this::toServerResponse);
+	}
+
+	protected Mono<ExecutionInput> customizeExecutionInput(ExecutionInput input, HttpHeaders headers) {
+		return Mono.just(input);
+	}
+
+	protected Mono<ExecutionResult> execute(ExecutionInput input) {
+		return Mono.fromFuture((graphQL.executeAsync(input)));
+	}
+
+	protected Mono<ServerResponse> toServerResponse(Mono<ExecutionResult> result) {
+		return result.map(ExecutionResult::toSpecification)
+				.flatMap(spec -> ServerResponse.ok().bodyValue(spec));
+	}
+
+}

spring-graphql-web/src/main/java/org/springframework/graphql/reactive/package-info.java

@@ -0,0 +1,6 @@
+@NonNullApi
+@NonNullFields
+package org.springframework.graphql.reactive;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-graphql-web/src/main/java/org/springframework/graphql/servlet/GraphQLHandler.java

@@ -0,0 +1,74 @@
+package org.springframework.graphql.servlet;
+
+import java.io.IOException;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+
+import javax.servlet.ServletException;
+
+import graphql.ExecutionInput;
+import graphql.ExecutionResult;
+import graphql.GraphQL;
+
+import org.springframework.graphql.GraphQLRequestBody;
+import org.springframework.http.HttpHeaders;
+import org.springframework.web.server.ServerErrorException;
+import org.springframework.web.server.ServerWebInputException;
+import org.springframework.web.servlet.function.ServerRequest;
+import org.springframework.web.servlet.function.ServerResponse;
+
+public class GraphQLHandler {
+
+	private final GraphQL graphQL;
+
+	public GraphQLHandler(GraphQL.Builder graphQL) {
+		this.graphQL = graphQL.build();
+	}
+
+	public ServerResponse handle(ServerRequest serverRequest) {
+		GraphQLRequestBody body;
+		try {
+			body = serverRequest.body(GraphQLRequestBody.class);
+		}
+		catch (ServletException | IOException ex) {
+			throw new ServerWebInputException("Failed to read request body", null, ex);
+		}
+		String query = body.getQuery();
+		if (query == null) {
+			query = "";
+		}
+		ExecutionInput input = ExecutionInput.newExecutionInput()
+				.query(query)
+				.operationName(body.getOperationName())
+				.variables(body.getVariables())
+				.build();
+		// Invoke GraphQLInterceptor's preHandle here
+		CompletableFuture<ExecutionResult> resultFuture =
+				customizeExecutionInput(input, serverRequest.headers().asHttpHeaders()).thenCompose(this::execute);
+		// Invoke GraphQLInterceptor's postHandle here
+		return customizeExecutionResult(resultFuture);
+	}
+
+	protected CompletableFuture<ExecutionInput> customizeExecutionInput(ExecutionInput input, HttpHeaders headers) {
+		return CompletableFuture.completedFuture(input);
+	}
+
+	protected CompletableFuture<ExecutionResult> execute(ExecutionInput input) {
+		return graphQL.executeAsync(input);
+	}
+
+	protected ServerResponse customizeExecutionResult(CompletableFuture<ExecutionResult> resultFuture) {
+		return resultFuture.isDone() ?
+				ServerResponse.ok().body(getResult(resultFuture)) :
+				ServerResponse.ok().body(resultFuture);
+	}
+
+	private ExecutionResult getResult(CompletableFuture<ExecutionResult> resultFuture) {
+		try {
+			return resultFuture.get();
+		}
+		catch (InterruptedException | ExecutionException ex) {
+			throw new ServerErrorException("Failed to get result", ex);
+		}
+	}
+}

spring-graphql-web/src/main/java/org/springframework/graphql/servlet/package-info.java

@@ -0,0 +1,6 @@
+@NonNullApi
+@NonNullFields
+package org.springframework.graphql.servlet;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;