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A root and branch review of error messages. (#650)
* A root and branch review of error messages. Now with toSpecification and extensions defined on them as well as an optional path * Fixed some tests that I missed * Documentation and made extensions be <String,Object> * PR feedback - moved helper into its own class
1 parent 02f34e6 commit bb8c54c

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+620
-122
lines changed

‎build.gradle‎

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@@ -39,6 +39,7 @@ dependencies {
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testCompile 'org.objenesis:objenesis:2.1'
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testCompile 'com.google.code.gson:gson:2.8.0'
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testCompile 'org.eclipse.jetty:jetty-server:9.4.5.v20170502'
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testCompile 'com.fasterxml.jackson.core:jackson-databind:2.8.8.1'
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testCompile 'org.slf4j:slf4j-simple:' + slf4jVersion
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testCompile 'org.awaitility:awaitility-groovy:3.0.0'
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testCompile 'com.graphql-java:java-dataloader:1.0.1'

‎docs/execution.rst‎

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@@ -89,6 +89,36 @@ Here is the code for the standard behaviour.
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}
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}
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If the exception you throw is itself a `GraphqlError` then it will transfer the message and custom extensions attributes from that exception
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into the `ExceptionWhileDataFetching` object. This allows you to place your own custom attributes into the graphql error that is sent back
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to the caller.
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For example imagine your data fetcher threw this exception. The `foo` and `fizz` attributes would be included in the resultant
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graphql error.
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.. code-block:: java
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class CustomRuntimeException extends RuntimeException implements GraphQLError {
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@Override
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public Map<String, Object> getExtensions() {
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Map<String, Object> customAttributes = new LinkedHashMap<>();
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customAttributes.put("foo", "bar");
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customAttributes.put("fizz", "whizz");
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return customAttributes;
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}
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@Override
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public List<SourceLocation> getLocations() {
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return null;
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}
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@Override
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public ErrorType getErrorType() {
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return ErrorType.DataFetchingException;
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}
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}
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You can change this behaviour by creating your own ``graphql.execution.DataFetcherExceptionHandler`` exception handling code and
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giving that to the execution strategy.
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@@ -107,6 +137,31 @@ behaviour.
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};
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ExecutionStrategy executionStrategy = new AsyncExecutionStrategy(handler);
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Serializing results to JSON
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---------------------------
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The most common way to call graphql is over HTTP and to expect a JSON response back. So you need to turn an
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`graphql.ExecutionResult` into a JSON payload.
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A common way to do that is use a JSON serialisation library like Jackson or GSON. However exactly how they interpret the
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data result is particular to them. For example `nulls` are important in graphql results and hence you must set up the json mappers
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to include them.
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To ensure you get a JSON result that confirms 100% to the graphql spec, you should call `toSpecification` on the result and then
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send that back as JSON.
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This will ensure that the result follows the specification outlined in http://facebook.github.io/graphql/#sec-Response
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.. code-block:: java
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ExecutionResult executionResult = graphQL.execute(executionInput);
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Map<String, Object> toSpecificationResult = executionResult.toSpecification();
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sendAsJson(toSpecificationResult);
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Mutations
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---------

‎src/main/java/graphql/ExceptionWhileDataFetching.java‎

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import graphql.language.SourceLocation;
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import java.util.Collections;
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import java.util.LinkedHashMap;
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import java.util.List;
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import java.util.Map;
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import static graphql.Assert.assertNotNull;
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import static java.lang.String.format;
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@PublicApi
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public class ExceptionWhileDataFetching implements GraphQLError {
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private final ExecutionPath path;
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private final String message;
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private final List<Object> path;
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private final Throwable exception;
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private final SourceLocation sourceLocation;
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private final List<SourceLocation> locations;
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private final Map<String, Object> extensions;
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public ExceptionWhileDataFetching(ExecutionPath path, Throwable exception, SourceLocation sourceLocation) {
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this.path = assertNotNull(path);
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this.path = assertNotNull(path).toList();
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this.exception = assertNotNull(exception);
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this.sourceLocation = sourceLocation;
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this.locations = Collections.singletonList(sourceLocation);
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this.extensions = mkExtensions(exception);
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this.message = mkMessage(path, exception);
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}
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private String mkMessage(ExecutionPath path, Throwable exception) {
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return format("Exception while fetching data (%s) : %s", path, exception.getMessage());
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}
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/*
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* This allows a DataFetcher to throw a graphql error and have "extension data" be transferred from that
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* exception into the ExceptionWhileDataFetching error and hence have custom "extension attributes"
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* per error message.
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*/
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private Map<String, Object> mkExtensions(Throwable exception) {
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Map<String, Object> extensions = null;
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if (exception instanceof GraphQLError) {
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Map<String, Object> map = ((GraphQLError) exception).getExtensions();
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if (map != null) {
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extensions = new LinkedHashMap<>();
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extensions.putAll(map);
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}
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}
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return extensions;
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}
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public Throwable getException() {
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@Override
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public String getMessage() {
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return format("Exception while fetching data (%s) : %s", path, exception.getMessage());
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return message;
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}
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@Override
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public List<SourceLocation> getLocations() {
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return Collections.singletonList(sourceLocation);
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return locations;
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}
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/**
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* The graphql spec says that that path field of any error should be a list
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* of path entries - http://facebook.github.io/graphql/#sec-Errors
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*
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* @return the path in list format
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*/
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public List<Object> getPath() {
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return path.toList();
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return path;
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}
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@Override
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public Map<String, Object> getExtensions() {
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return extensions;
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}
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@Override
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return "ExceptionWhileDataFetching{" +
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"path=" + path +
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"exception=" + exception +
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"sourceLocation=" + sourceLocation +
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"locations=" + locations +
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'}';
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}
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@SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
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@Override
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public boolean equals(Object o) {
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return Helper.equals(this, o);
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return GraphqlErrorHelper.equals(this, o);
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}
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@Override
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public int hashCode() {
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return Helper.hashCode(this);
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return GraphqlErrorHelper.hashCode(this);
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}
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}

‎src/main/java/graphql/ExecutionResultImpl.java‎

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import java.util.List;
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import java.util.Map;
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import static java.util.stream.Collectors.toList;
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@Internal
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public class ExecutionResultImpl implements ExecutionResult {
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result.put("data", data);
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}
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if (errors != null && !errors.isEmpty()) {
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result.put("errors", errors);
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result.put("errors", errorsToSpec(errors));
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}
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if (extensions != null) {
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result.put("extensions", extensions);
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}
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return result;
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}
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private Object errorsToSpec(List<GraphQLError> errors) {
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return errors.stream().map(GraphQLError::toSpecification).collect(toList());
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}
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@Override
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public String toString() {
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return "ExecutionResultImpl{" +

‎src/main/java/graphql/GraphQLError.java‎

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import graphql.language.SourceLocation;
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import java.util.List;
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import java.util.Map;
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/**
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* @see <a href="https://facebook.github.io/graphql/#sec-Errors">GraphQL Spec - 7.2.2 Errors</a>
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*/
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List<SourceLocation> getLocations();
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/**
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* @return an enum classifying this error
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*/
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ErrorType getErrorType();
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/**
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* The graphql spec says that the (optional) path field of any error should be a list
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* of path entries - http://facebook.github.io/graphql/#sec-Errors
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*
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* @return the path in list format
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*/
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default List<Object> getPath() {
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return null;
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}
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/**
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* The graphql specification says that result of a call should be a map that follows certain rules on what items
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* should be present. Certain JSON serializers may or may interpret the error to spec, so this method
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* is provided to produce a map that strictly follows the specification.
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*
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* See : <a href="http://facebook.github.io/graphql/#sec-Errors">http://facebook.github.io/graphql/#sec-Errors</a>
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*
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* @return a map of the error that strictly follows the specification
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*/
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default Map<String, Object> toSpecification() {
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return GraphqlErrorHelper.toSpecification(this);
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}
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/**
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* This little helper allows GraphQlErrors to implement
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* common things (hashcode/ equals) more easily
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* @return a map of error extensions or null if there are none
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*/
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@SuppressWarnings("SimplifiableIfStatement")
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class Helper {
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public static int hashCode(GraphQLError dis) {
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int result = dis.getMessage() != null ? dis.getMessage().hashCode() : 0;
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result = 31 * result + (dis.getLocations() != null ? dis.getLocations().hashCode() : 0);
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result = 31 * result + dis.getErrorType().hashCode();
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return result;
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}
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public static boolean equals(GraphQLError dis, Object o) {
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if (dis == o) {
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return true;
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}
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if (o == null || dis.getClass() != o.getClass()) return false;
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GraphQLError dat = (GraphQLError) o;
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if (dis.getMessage() != null ? !dis.getMessage().equals(dat.getMessage()) : dat.getMessage() != null)
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return false;
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if (dis.getLocations() != null ? !dis.getLocations().equals(dat.getLocations()) : dat.getLocations() != null)
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return false;
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return dis.getErrorType() == dat.getErrorType();
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}
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default Map<String, Object> getExtensions() {
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return null;
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}
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}

‎src/main/java/graphql/GraphqlErrorHelper.java‎

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package graphql;
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import graphql.language.SourceLocation;
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import java.util.LinkedHashMap;
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import java.util.List;
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import java.util.Map;
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import static java.util.stream.Collectors.toList;
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/**
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* This little helper allows GraphQlErrors to implement
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* common things (hashcode/ equals ) and to specification more easily
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*/
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@SuppressWarnings("SimplifiableIfStatement")
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public class GraphqlErrorHelper {
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public static Map<String, Object> toSpecification(GraphQLError error) {
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Map<String, Object> errorMap = new LinkedHashMap<>();
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errorMap.put("message", error.getMessage());
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if (error.getLocations() != null) {
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errorMap.put("locations", locations(error.getLocations()));
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}
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if (error.getPath() != null) {
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errorMap.put("path", error.getPath());
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}
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if (error.getExtensions() != null) {
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errorMap.put("extensions", error.getExtensions());
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}
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return errorMap;
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}
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public static Object locations(List<SourceLocation> locations) {
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return locations.stream().map(GraphqlErrorHelper::location).collect(toList());
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}
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public static Object location(SourceLocation location) {
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Map<String, Integer> map = new LinkedHashMap<>();
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map.put("line", location.getLine());
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map.put("column", location.getColumn());
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return map;
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}
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public static int hashCode(GraphQLError dis) {
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int result = dis.getMessage() != null ? dis.getMessage().hashCode() : 0;
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result = 31 * result + (dis.getLocations() != null ? dis.getLocations().hashCode() : 0);
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result = 31 * result + (dis.getPath() != null ? dis.getPath().hashCode() : 0);
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result = 31 * result + dis.getErrorType().hashCode();
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return result;
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}
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public static boolean equals(GraphQLError dis, Object o) {
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if (dis == o) {
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return true;
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}
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if (o == null || dis.getClass() != o.getClass()) return false;
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GraphQLError dat = (GraphQLError) o;
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if (dis.getMessage() != null ? !dis.getMessage().equals(dat.getMessage()) : dat.getMessage() != null)
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return false;
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if (dis.getLocations() != null ? !dis.getLocations().equals(dat.getLocations()) : dat.getLocations() != null)
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return false;
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if (dis.getPath() != null ? !dis.getPath().equals(dat.getPath()) : dat.getPath() != null)
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return false;
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return dis.getErrorType() == dat.getErrorType();
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}
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}

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