Query Functionality with `onCompleted` is broken in v3.0.0 release (CodeSandbox repro)

Some core lazy querying functionality through useLazyQuery seems a bit off.

Specifically, when a lazy query (through a useLazyQuery hook) returns an error, then Apollo seems to start endlessly querying the server. The same thing happens if you give it a fetchPolicy of network-only (or anything that doesn’t search the cache first).

Related: https://github.com/apollographql/react-apollo/issues/4044

At the same time, if the lazy query function (returned by useLazyQuery) gets called more than 1 times, then no callbacks are fired. The onCompleted doesn’t fire again. The onCompleted fires on the 1st successful run of the “query” function and then consecutive invocations of the lazy query function, don’t trigger onCompleted callback (they should, since you can’t have conditional business logic based on whether the data is cached or not!)

Related: https://github.com/apollographql/react-apollo/issues/4000

Funnily enough, using client.query() works fine. All this used to work perfectly during the beta (I think I’ve verified that something occurred after @apollo/client@v3.0.0-beta.43), but now it doesn’t.

UPDATE: I’ve added a codesandbox that reproduces it

Intended outcome:

• Lazy query errors shouldn’t trigger endless API querying
• A network-only fetch policy shouldn’t trigger endless API querying on a lazy query
• onCompleted should fire every time a lazy query gets successfully executed

Actual outcome:

• Lazy query errors & network-only fetch policy start an endless loop of requests
• onCompeted gets fired at most once regardless of the number of invocations

How to reproduce the issue:

• Take a lazy query and change the fetchPolicy to network-only or force an API error on a lazy query
• Click a button that triggers a lazy query multiple time, while observing the number of invocations of the onCompleted callback.

Versions System: OS: macOS 10.15.2 Binaries: Node: 12.18.0 - /usr/local/bin/node Yarn: 1.19.0 - /usr/local/bin/yarn npm: 6.14.4 - /usr/local/bin/npm Browsers: Chrome: 83.0.4103.116 Firefox: 72.0.2 Safari: 13.0.4 npmPackages: @apollo/client: ^3.0.2 => 3.0.2 apollo-link-error: ^1.1.12 => 1.1.13

[3nvi]

@benjamn and @hwillson Thanks for tackling this.

Current State of things

As of the moment of writing, in 3.1.1:

• An errorred query no longer re-renders endlessly 🎉
• A cache-first query with onCompleted and/or onError no longer re-renders endlessly 🎉
• A network-only query no longer pings the server endlessly 🎉

Pending bugs

• The onCompleted callback should always fire whenever a query is resolved (either from network or cache). https://github.com/apollographql/react-apollo/issues/4000

Currently only network-only requests have their onCompleted fired after every query execution. For cache-first ones, the onCompleted fires only once. Unless this is documented somewhere, I would flag this as a bug since our onCompleted logic shouldn’t have to account for the origin of this data, i.e. It should be cache agnostic

• Changing a query variable on a lazy query should not automatically fire it. https://github.com/apollographql/react-apollo/issues/3729

This should definitely happen for useQuery hooks, but not for useLazyQuery hooks (since they wouldn’t be lazy anymore). Again if this is the expected functionality it should ideally be documented

Reproduction of pending bugs

You can observe both these bugs in the following codesandbox --> https://codesandbox.io/s/apollo-reference-equality-op12z?file=/src/App.js

• To reproduce the onCompleted error: Change fetchPolicy to cache-first, click “Run Query” multiple times and see how onCompleted only fires once

• To reproduce the variables with useLazyQuery error: Click “Run Query” once and then start clicking “Change foo”. Clicking “change foo” should not cause a query to run

Additional Context

Out of the two bugs listed above (in the order that they are mentioned):

• The first is within the scope of this ticket and a requirement in order to close it
• The second isn’t necessarily related to this ticket (although mentioned) and I understand that it may require a more complex solution through a modification of your query observables. Thus, I’m willing to port (2) to another issue in order to help close the existing one

Thanks again!

[hwillson]

This issue was fixed in https://github.com/apollographql/apollo-client/pull/6588, and will be coming in @apollo/client@3.1.0 very soon.