Improve return type of customFormatErrorFn

graphql-community · Nov 24, 2021 · eaf1bb4 · eaf1bb4
1 parent 1e03a14
commit eaf1bb4
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Showing 3 changed files with 25 additions and 14 deletions.
diff --git a/src/__tests__/http-test.ts b/src/__tests__/http-test.ts
@@ -2369,7 +2369,9 @@ describe('GraphQL-HTTP tests', () => {
           urlString(),
           graphqlHTTP({
             schema: TestSchema,
-            customFormatErrorFn: () => null,
+            customFormatErrorFn: () => ({
+              message: 'Some generic error message.',
+            }),
             extensions({ result }) {
               return { preservedResult: { ...result } };
             },
@@ -2386,7 +2388,7 @@ describe('GraphQL-HTTP tests', () => {
       expect(response.status).to.equal(200);
       expect(JSON.parse(response.text)).to.deep.equal({
         data: { thrower: null },
-        errors: [null],
+        errors: [{ message: 'Some generic error message.' }],
         extensions: {
           preservedResult: {
             data: { thrower: null },

diff --git a/src/index.js b/src/index.js
@@ -3,10 +3,12 @@
 import type {
   ExecutionArgs,
   ExecutionResult,
+  FormattedExecutionResult,
   GraphQLError,
   GraphQLSchema,
   GraphQLFieldResolver,
   GraphQLTypeResolver,
+  GraphQLFormattedError,
   ValidationContext,
   ASTVisitor,
 } from 'graphql';
@@ -91,7 +93,10 @@ export type OptionsData = {|
    * fulfilling a GraphQL operation. If no function is provided, GraphQL's
    * default spec-compliant `formatError` function will be used.
    */
-  customFormatErrorFn?: ?(error: GraphQLError, context?: ?any) => mixed,
+  customFormatErrorFn?: ?(
+    error: GraphQLError,
+    context?: ?any,
+  ) => GraphQLFormattedError,
 
   /**
    * An optional function which will be used to create a document instead of
@@ -103,7 +108,7 @@ export type OptionsData = {|
    * `formatError` is deprecated and replaced by `customFormatErrorFn`. It will
    *  be removed in version 1.0.0.
    */
-  formatError?: ?(error: GraphQLError, context?: ?any) => mixed,
+  formatError?: ?(error: GraphQLError, context?: ?any) => GraphQLFormattedError,
 
   /**
    * An optional function for adding additional metadata to the GraphQL response
@@ -383,27 +388,31 @@ function graphqlHTTP(options: Options): Middleware {
     if (response.status === 200 && result && !result.data) {
       response.status = 500;
     }
-    // Format any encountered errors.
-    if (result && result.errors) {
-      (result: any).errors = result.errors.map((err) =>
-        formatErrorFn(err, context),
-      );
-    }
+
+    const formattedResult: FormattedExecutionResult =
+      result && result.errors
+        ? {
+            ...result,
+            errors: result.errors.map((err) => formatErrorFn(err, context)),
+          }
+        : result;
 
     // If allowed to show GraphiQL, present it instead of JSON.
     if (showGraphiQL) {
       const payload = renderGraphiQL({
         query,
         variables,
         operationName,
-        result,
+        result: formattedResult,
         options: typeof showGraphiQL !== 'boolean' ? showGraphiQL : {},
       });
       response.type = 'text/html';
       response.body = payload;
     } else {
       // Otherwise, present JSON directly.
-      const payload = pretty ? JSON.stringify(result, null, 2) : result;
+      const payload = pretty
+        ? JSON.stringify(formattedResult, null, 2)
+        : formattedResult;
       response.type = 'application/json';
       response.body = payload;
     }

diff --git a/src/renderGraphiQL.js b/src/renderGraphiQL.js
@@ -1,6 +1,6 @@
 // @flow strict
 
-import type { ExecutionResult } from 'graphql';
+import type { FormattedExecutionResult } from 'graphql';
 
 type EditorThemeParam =
   | {|
@@ -13,7 +13,7 @@ type GraphiQLData = {|
   query: ?string,
   variables: ?{ [param: string]: mixed },
   operationName: ?string,
-  result?: ?ExecutionResult,
+  result?: ?FormattedExecutionResult,
   options: ?GraphiQLOptions,
 |};