apollo-link-error

Handle and inspect errors in your GraphQL network stack.

Use this link to do some custom logic when a GraphQL or network error happens:

import { onError } from "apollo-link-error";

const link = onError(({ graphQLErrors, networkError }) => {
  if (graphQLErrors)
    graphQLErrors.map(({ message, locations, path }) =>
      console.log(
        `[GraphQL error]: Message: ${message}, Location: ${locations}, Path: ${path}`
      )
    );
  if (networkError) console.log(`[Network error]: ${networkError}`);
});

Apollo Link is a system of modular components for GraphQL networking. Read the docs to learn how to use this link with libraries like Apollo Client and graphql-tools, or as a standalone client.

Callback

Error Link takes a function that is called in the event of an error. This function is called with an object containing the following keys:

  • operation: The Operation that errored
  • response: The result returned from lower down in the link chain
  • graphQLErrors: An array of errors from the GraphQL endpoint
  • networkError: Any error during the link execution or server response, that wasn’t delivered as part of the errors field in the GraphQL result

Error categorization

An error is passed as a networkError if a link further down the chain called the error callback on the observable. In most cases, graphQLErrors is the errors field of the result from the last next call.

A networkError can contain additional fields, such as a GraphQL object in the case of a failing HTTP status code from apollo-link-http. In this situation, graphQLErrors is an alias for networkError.result.errors if the property exists.

Ignoring errors

If you want to conditionally ignore errors, you can set response.errors = null; within the error handler:

onError(({ response, operation }) => {
  if (operation.operationName === "IgnoreErrorsQuery") {
    response.errors = null;
  }
});
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