updateQuery documentation error

[KhalfaniW]

The function signature in the documentation for updateQuery says it takes 2 parameters and returns TData
(previousResult: TData, options: { variables: TVariables }) => TData

https://www.apollographql.com/docs/react/api/react/hooks/#updatequery

However in the code it takes a mapFn parameter and returns void

apollo-client/src/core/ObservableQuery.ts

Line 602 in 3d039f8

public updateQuery<TVars = TVariables>(

Please also explain what mapFn is supposed to do because I was confused.

[jpvajda]

@KhalfaniW thanks for reporting this. I've added this issue to an Umbrella issue to do some documentation updates.

[MrDoomBringer]

@KhalfaniW Thanks for the report. You're correct, updateQuery only takes 1 argument, MapFn.

MapFn is a function with the signature (previousResult: TData, options: { variables: TVariables }) => TData, meaning it takes the data object you get from useQuery, etc., an optional variables object, and returns a modified version of that data.

You can see usage in Reading and Writing Data to the Cache.

Here's a quick example written in the fullstack tutorial's launch page.