The onCompleted callback of the useQuery hook executes on data mutations

Intended outcome: The onCompleted callback in the useQuery hook shouldn’t be executed when data has changed by a mutation. The callback function needs to be called only once, after the data has been fetched.

Actual outcome: The onCompleted callback of the useQuery hook executes on each data change.

How to reproduce the issue: https://codesandbox.io/s/mutations-oncompleted-callback-execution-2n2yic?file=/src/index.js

1. Add a todo
2. Update the todo

Switch between @apollo/client versions to see the behavior of the onCompleted callback varies between 3.4.x and 3.5.x, 3.6.x versions. On version 3.4.x, the onCompleted callback is called only once, when data fetches, while on versions 3.5.x and 3.6.x, the callback is executed two times, when data fetches and additionally after the mutation.

Versions 3.4.14: works as expected. 3.5.x and 3.6.x: the onCompleted callback of the useQuery hook executes on data mutations.

[alessbell]

Appreciate the reproduction here, @krasai! I have https://github.com/apollographql/apollo-client/pull/10229 open with the fix, I’ll update this issue again when it’s merged and released. Thanks everyone 🙇‍♀️

[alessbell]

The fix is now available in the current 3.8 alpha release which can be installed via npm i @apollo/client@alpha.