# queryThunk

## Overview

A core action instantiated during (buildThunks). `queryThunk` leverages `createAsyncThunk` to initiate the query process and is used extensively throughout the codebase both as a match case and to initiate queries. The payload for the query is built using [executeEndpoint]

## Functions

Before executing the payload creator function in [executeEndpoint], `queryThunk` executes two functions:

### `getPendingMeta()`

1. `getPendingMeta()` - adds additional metadata to the action to be used in reducers or middleware.
   1. `startedTimeStamp`
   2. `SHOULD_AUTOBATCH`

### `condition()`

Performs conditional checks based on the provided args to decide whether the query should continue or not. (also attaches the field `dispatchConditionRejected: true` as confirmation that the condition was checked)

```ts no-transpile
if (isUpsertQuery(queryThunkArgs)) { return true }
if (requestState?.status === "pending") { return false }
if (isForcedQuery(queryThunkArgs, state)) { return true }
if (isQueryDefinition(endpointDefinition) && endpointDefinition?.forceRefetch?.({ return true }
if (fulfilledVal) { return false }
else return true
```

## Middleware Uses

### buildSlice

The query endpoint is built almost entirely off of the `extraReducers` matching a `queryThunk` pending/fulfilled/rejected actions and updates the `querySubstate` plus meta data accordingly. The query slice utilises the condition and attached metadata created by a `queryThunk`.

`buildSlice` additionally matches resolved (rejected OR fulfilled) `queryThunks` to update providedTags.

### invalidationByTags

matches against all rejected/fulfilled cases for `queryThunk`

### Polling

matches against multiple queryThunk cases

```js no-transpile
if (
  queryThunk.pending.match(action) ||
  (queryThunk.rejected.match(action) && action.meta.condition)
) {
  updatePollingInterval(action.meta.arg, mwApi)
}
if (
  queryThunk.fulfilled.match(action) ||
  (queryThunk.rejected.match(action) && !action.meta.condition)
) {
  startNextPoll(action.meta.arg, mwApi)
}
```

### cacheLifecycle

uses `queryThunk` matching to differentiate between mutation cache and query cache handling

### queryLifecycle

leverages the createAsyncThunk pending/fulfilled/rejected to extend the lifecycle with query specific traits, also uses it to handle onQueryStarted

### batchedActions

### buildMiddleware

`refetchQuery` refires queryThunk with arguments for the `queryThunk` to determine if the query should be sent or not