Improved Typings

[danilobuerger]

• Deprecated MutationFunc in favor of MutationFn.

Internally the graphql hoc uses the Mutation comp and passes the mutate
func along, so the typing should reflect this

• Added missing callbacks to MutationOpts

These callbacks get passed from the hoc to the Mutation comp

[hwillson]

Looks great @danilobuerger - thanks very much!

[williamboman]

I think the return type of MutationFn is a bit weird now with void being a possible promise result value, why? This breaks our current types and we need to do a null check in every place where we consume the promise result.

Example of what we need to do in order to satisfy type safety:

   withHandlers<Props, HandlerProps>({
     handleConfirmSubmit: (props: GraphqlProps) => async (formData: ConfirmSubmitFormData) => {
-      const { data } = await props.createStuffMutator.mutate({ variables: formData })
-      doStuffWith(data)
+      const response = await props.createStuffMutator.mutate({ variables: formData })
+      if (typeof response === "object") {
+        const { data } = response
+        doStuffWith(data)
+      }
     }
   })

[hwillson]

@williamboman Any chance you could submit a PR to improve this? Thanks!

[williamboman]

Sure! I'm not sure whether it's a correct assumption to make that void is never a valid Promise result data type for mutations though, I'll have to 🔎 the code (unless anyone have any pointers 😊)

[danilobuerger]

@williamboman the return type of MutationFn didn't change. When using the Mutation comp instead of the graphql hoc (as in your example) the void check was already necessary. However, it might not be needed at all as the return type of ApolloClient.mutate (which is used internally) is Promise<FetchResult<T>> (https://github.com/apollographql/apollo-client/blob/master/packages/apollo-client/src/ApolloClient.ts#L269)