[Error] Mutation : the application attempted to write an object with no provided id but the store already contains an id

Hello guys,

Sorry it might be a trivial problem but I’m stuck, in my Apollo testing and learning process, by an error my mutation generates and I’m coming down to you to help me.

Intended outcome:

Mutating by adding a new friend to a user and updating the state with the newly added friend.

import { graphql, compose } from 'react-apollo';
import { connect } from 'react-redux';
import update from 'immutability-helper';

...

const addFriend = graphql(ADD_FRIEND_MUTATION, {
  props: ({ mutate }) => ({
    addFriend: username =>
      mutate({
        variables: { username },
        updateQueries: {
          user: (previousResult, { mutationResult }) => {
            const newFriend = mutationResult.data.addFriend;
            return update(previousResult, {
              user: {
                friends: {
                  $push: [newFriend],
                },
              },
            });
          },
        },
      }),
  }),
});

...

export default compose(connect(mapStateToProps, mapDispatchToProps), userQuery, addFriend)(People);

Actual outcome:

The mutation works db-wise, but the client does not want to update the app/redux state.

Weirdly the updateQueries is called twice. The first time with the “right” previousResult object, the second time with a much smaller object without id. Then the error pops. After refresh of the app, the friend is well added.

Here is the error : the application attempted to write an object with no provided id but the store already contains an id of User:18 for this object.

How to reproduce the issue:

Directly from my little test project repo : https://github.com/xavierlefevre/chat

Here is the react container with the front mutation : https://github.com/xavierlefevre/chat/blob/master/client/src/pages/people/people.container.js

In order to install the project :

• Back
  • cd chat/server
  • yarn install
  • yarn start
• Front
  • cd chat/client
  • yarn install
  • react-native run-ios
  • login with a user logged by the express server in your terminal
  • go to the tab “people”
  • click on the top right “plus”
  • add a user, once again output by the express server in your terminal
  • witness the error

Hope my issue is filled correctly, and thanks a bunch for the help.

[helfer]

Ah, I think I see the problem now. Your FRIENDS_QUERY doesn’t ask for the user’s id. That way Apollo Client cannot calculate a unique id for the object, and you get the error message that you saw. I’m glad you figured out a solution on your own though! 🙂

[xavierlefevre]

@helfer

I fixed the issue. Here is my commit : https://github.com/xavierlefevre/chat/commit/11c84529c5fc16168470109f07ab83cbe15ca181

The thing I understood :

• I query USER_QUERY when arriving on the app, retrieving many information for this user as id, username, friends, groups etc.
• In the page of this issue, I then make a FRIENDS_QUERY that only retrieves the friends of this same user
• Once the mutation to add a friend to the user completes, I don’t know why, but it triggers twice, once with a full user in previousResult (id, username, etc.), and a second time with a user only matching the FRIENDS_QUERY (only friends).

So I decided to remove FRIENDS_QUERY and query/retrieve (again) USER_QUERY for this page as well, in order to make sure it has the same object shape. But I am not sure why yet I needed to do that.

If things are clear for you and you would have any hint for me, it would be amazing.

Thanks anyhow !