Apollo-client returns "400 (Bad Request) Error" on sending mutation to server

Question

I am currently using the vue-apollo package for Apollo client with VueJs stack with django and graphene-python for my GraphQl API.

I have a simple setup with vue-apollo below:

import Vue from 'vue'
import { ApolloClient } from 'apollo-client'
import { HttpLink } from 'apollo-link-http'
import { InMemoryCache } from 'apollo-cache-inmemory'
import VueApollo from 'vue-apollo'
import Cookies from 'js-cookie'


const httpLink = new HttpLink({
  credentials: 'same-origin',
  uri: 'http://localhost:8000/api/',
})

// Create the apollo client
const apolloClient = new ApolloClient({
  link: httpLink,
  cache: new InMemoryCache(),
  connectToDevTools: true,
})

export const apolloProvider = new VueApollo({
  defaultClient: apolloClient,
})

// Install the vue plugin
Vue.use(VueApollo)

I also have CORS setup on my Django settings.py with the django-cors-headers package. All queries and mutations resolve fine when I use graphiQL or the Insomnia API client for chrome, but trying the mutation below from my vue app:

'''

import gql from "graphql-tag";
import CREATE_USER from "@/graphql/NewUser.gql";

export default {
  data() {
    return {
      test: ""
    };
  },
  methods: {
    authenticateUser() {
      this.$apollo.mutate({
        mutation: CREATE_USER,
        variables: {
          email: "[email protected]",
          password: "pa$$word",
          username: "testuser"
        }
      }).then(data => {
          console.log(result)
      })
    }
  }
};

NewUser.gql

mutation createUser($email: String!, $password: String!, $username: String!) {
  createUser (username: $name, password: $password, email: $email)
  user {
    id
    username
    email
    password
  }
}

returns with the error response below:

POST http://localhost:8000/api/ 400 (Bad Request)

ApolloError.js?d4ec:37 Uncaught (in promise) Error: Network error: Response not successful: Received status code 400

Regular queries in my vue app, however, work fine resolving the right response, except mutations, so this has me really baffled

Answer 1

400 errors generally mean there's something off with the query itself. In this instance, you've defined (and you're passing in) a variable called $username -- however, your query references it as $name on line 2.

Answer 2

In addition to graphiQL, I would like to add that apollo-link-error package would also had been of great help. By importing its error handler { onError }, you can obtain great detail through the console about errors produced at network and application(graphql) level :

import { onError } from 'apollo-link-error';
import { ApolloLink } from 'apollo-link';

const errorLink = onError(({ graphQLErrors, networkError }) => {
  if (graphQLErrors) {
    console.log('graphQLErrors', graphQLErrors);
  }
  if (networkError) {
    console.log('networkError', networkError);
  }
});

const httpLink = ...

const link = ApolloLink.from([errorLink, httpLink]);

const client = new ApolloClient({
  ...,
  link,
  ...
});

By adding this configuration where you instantiate your Apollo Client, you would have obtained an error similar to this one:

GraphQLError{message: "Syntax Error: Expected {, found Name "createUser""}

Further information can be found in Apollo Doc - Error handling: https://www.apollographql.com/docs/react/features/error-handling. Hope it helps in the future.

Answer 3

For me, it was the fact that I was using a field not defined in the GraphQL schema. Always be careful!