Fix Resolver type (#4943)

* Match Resolver and Resolvers

The exported type for Resolve differs from Resolvers. This causes some type errors when trying to type your resolvers. Where we call the resolver we only use the indicated parameters (fieldName never gets passed to the resolver, e.g https://github.com/apollographql/apollo-client/blob/master/packages/apollo-client/src/core/LocalState.ts#L391). Also it is aligned with the GraphQL Resolver API

* Add Changelog

CHANGELOG.md

@@ -38,7 +38,7 @@
 - Documentation updates.  <br/>
   [@michael-watson](https://github.com/michael-watson) in [#4940](https://github.com/apollographql/apollo-client/pull/4940)  <br/>
   [@hwillson](https://github.com/hwillson) in [#4969](https://github.com/apollographql/apollo-client/pull/4969)
-
+- Fix type for `Resolver` and use it in the definition of `Resolvers`. <br /> [@peoplenarthax](https://github.com/peoplenarthax) 
 
 ## Apollo Client (2.6.1)
 

packages/apollo-client/src/core/LocalState.ts

@@ -36,11 +36,10 @@ import { Resolvers, OperationVariables } from './types';
 import { capitalizeFirstLetter } from '../util/capitalizeFirstLetter';
 
 export type Resolver = (
-  fieldName: string,
-  rootValue: any,
-  args: any,
-  context: any,
-  info: {
+  rootValue?: any,
+  args?: any,
+  context?: any,
+  info?: {
     field: FieldNode;
   },
 ) => any;

packages/apollo-client/src/core/types.ts

@@ -3,6 +3,7 @@ import { DocumentNode, GraphQLError } from 'graphql';
 
 import { QueryStoreValue } from '../data/queries';
 import { NetworkStatus } from './networkStatus';
+import { Resolver } from './LocalState';
 
 export type QueryListener = (
   queryStoreValue: QueryStoreValue,
@@ -48,11 +49,6 @@ export type MutationQueryReducersMap<T = { [key: string]: any }> = {
 
 export interface Resolvers {
   [key: string]: {
-    [field: string]: (
-      rootValue?: any,
-      args?: any,
-      context?: any,
-      info?: any,
-    ) => any;
+    [ field: string ]: Resolver;
   };
 }