useOptimistic
Instantly update UI with mutation results created directly in an application whilst awaiting updated content from Content Lake.
The useOptimistic hook uses a local document store to enable developers to opt-in to instant updates for specific content. UI can be updated with the anticipated result of a mutation, avoiding the delay required when submitting and refetching data from Content Lake.
It's primarily used for enabling drag and drop functionality for Visual Editing. You can learn more about how to use it in the Drag and drop documentation.
useOptimistic(passthrough, reducer):
Returns
When no mutations are pending, the hook returns the original passthrough value.
When mutations are pending, it returns the optimistically updated state as determined by the reducers.
In production, the
useOptimisticis a no-op and will always return the passthrough value.Parameters
passthroughT
The base state that should be modified optimistically. Most often the array of items that you want to make drag and droppable in Presentation.
reducerOptimisticReducer<T,U>|Array<OptimisticReducer<T,U>>
A reducer function or array of reducers that determine how the state should be updated in response to optimistic mutations.
Reducers(state, action):
A reducer function or array of reducers that determine how the state should be updated in response to optimistic mutations.
Parameters
stateT
The current state, equal to the passthrough value when no reducers have been applied.
actionOptimisticReducerAction<U>
The action received by the reducer, used to optimistically update the state.
Reducer actions
Here is the signature for the action parameter for reducers:
documentU
The document that was updated
idstring
The published document ID (the same as the
_id)originalIdstring
The original document ID
type'appear' | 'mutate' | 'disappear
The type of action occurring (only
mutateis currently supported)