Ensure onSuccess is called with transformed data when tranformResponse is used

[asherccohen]

Following the conversation with @phryneas on the discord channel (link ), we noticed that the flow of responses in callback methods with a transformResponse does not guarantee the same shape of data, this requires to transform in each callback (potential bottleneck and error prone).

I don't have the time for a PR, so here's the steps to get there.

How to reproduce:

• create a service
• add a transformResponse callback (with a simple fn that changes the shape of response)
• add an onSuccess callback and log "result".

Expected:
"result" should be transformed

What happens:
"result" is not transformed

Code:

rtk-query/src/core/buildThunks.ts

Lines 235 to 241 in c769479

	if (result.error) throw new HandledError(result.error, result.meta);
	if (endpointDefinition.onSuccess)
	endpointDefinition.onSuccess(arg.originalArgs, queryApi, result.data, result.meta);
	return {
	fulfilledTimeStamp: Date.now(),
	result: await transformResponse(result.data, result.meta),
	};

The above lines of code demonstrate that onSuccess and onError are called with the original data.

It's a bit unexpected that onSuccess and onError are called before the data is persisted in the store
Could be moved out of the asyncThunk into initiate.

[phryneas]

Might actually make sense to tackle this together with #215 and move all lifecycle event handling into one central place in the middleware.

[asherccohen]

EDIT: Check that also selectFromResult adheres to the same shape.

[phryneas]

@asherccohen it should, that one reads from the redux store wayyy later

[phryneas]

This is on the integration branch right now, closing it here.