CombinedGraphQLErrors

Represents the combined list of GraphQL errors returned from the server in a GraphQL response. This error type is used when your GraphQL operation returns errors in the errors field of the response.

When your GraphQL operation encounters errors on the server side (such as resolver errors, validation errors, or syntax errors), the server returns these errors in the errors array of the GraphQL response. Apollo Client wraps these errors in a CombinedGraphQLErrors object, which provides access to the individual errors while maintaining additional context about the response.

1 import { CombinedGraphQLErrors } from "@apollo/client/errors";
2
3 // Check if an error is a CombinedGraphQLErrors object
4 if (CombinedGraphQLErrors.is(error)) {
5   // Access individual GraphQL errors
6   error.errors.forEach((graphQLError) => {
7     console.log(graphQLError.message);
8     console.log(graphQLError.path);
9     console.log(graphQLError.locations);
10   });
11
12   // Access the original GraphQL result
13   console.log(error.result);
14 }

By default, CombinedGraphQLErrors formats the message property by joining each error's message field with a newline. To customize the format of the message, such as changing the delimiter or adding a message prefix, override the static formatMessage method.

The following example demonstrates how to format the error message by joining each error with a comma.

1import { CombinedGraphQLErrors } from "@apollo/client/errors";
2
3CombinedGraphQLErrors.formatMessage = (errors) => {
4  return errors.map((error) => error.message).join(", ");
5};

See the formatMessage docs for details about the parameters provided to the formatMessage function.

To format part of the message using the default message formatter, call the defaultFormatMessage function provided to the options argument of your message formatter.

The following example prepends a string to the message and uses the default message formatter to format the error messages.

1CombinedGraphQLErrors.formatMessage = (errors, { defaultFormatMessage }) => {
2  return `[GraphQL errors]: ${defaultFormatMessage(errors)}`;
3};

A method that determines whether an error is a CombinedGraphQLErrors object. This method enables TypeScript to narrow the error type.

A function that formats the error message used for the error's message property. Override this method to provide your own formatting.

The formatMessage function is called by the CombinedGraphQLErrors constructor to provide a formatted message as the message property of the CombinedGraphQLErrors object. Follow the "Providing a custom message formatter" guide to learn how to modify the message format.