Pass a context object around with store data

Prompted by #376's brittleness; this helps keep common state/configuration around when performing a query.

---

Also, as part of this, I noticed there are two seemingly unused functions: `diffQueryAgainstStore`, `diffFragmentAgainstStore`

src/QueryManager.ts

@@ -379,12 +379,14 @@ export class QueryManager {
           }
         } else {
           const resultFromStore = readSelectionSetFromStore({
-            store: this.getDataWithOptimisticResults(),
+            context: {
+              store: this.getDataWithOptimisticResults(),
+              fragmentMap: queryStoreValue.fragmentMap,
+            },
             rootId: queryStoreValue.query.id,
             selectionSet: queryStoreValue.query.selectionSet,
             variables: queryStoreValue.variables,
             returnPartialData: options.returnPartialData || options.noFetch,
-            fragmentMap: queryStoreValue.fragmentMap,
           });
 
           if (observer.next) {
@@ -622,12 +624,14 @@ export class QueryManager {
       // query, use the query diff algorithm to get as much of a result as we can, and identify
       // what data is missing from the store
       const { missingSelectionSets, result } = diffSelectionSetAgainstStore({
+        context: {
+          store: this.store.getState()[this.reduxRootKey].data,
+          fragmentMap: queryFragmentMap,
+        },
         selectionSet: querySS.selectionSet,
-        store: this.store.getState()[this.reduxRootKey].data,
         throwOnMissingField: false,
         rootId: querySS.id,
         variables,
-        fragmentMap: queryFragmentMap,
       });
 
       initialResult = result;
@@ -727,12 +731,14 @@ export class QueryManager {
               // this will throw an error if there are missing fields in
               // the results if returnPartialData is false.
               resultFromStore = readSelectionSetFromStore({
-                store: this.getApolloState().data,
+                context: {
+                  store: this.getApolloState().data,
+                  fragmentMap: queryFragmentMap,
+                },
                 rootId: querySS.id,
                 selectionSet: querySS.selectionSet,
                 variables,
                 returnPartialData: returnPartialData || noFetch,
-                fragmentMap: queryFragmentMap,
               });
               // ensure multiple errors don't get thrown
               /* tslint:disable */

src/data/diffAgainstStore.ts

@@ -42,6 +42,13 @@ export interface DiffResult {
   missingSelectionSets?: SelectionSetWithRoot[];
 }
 
+// Contexual state and configuration that is used throught a request from the
+// store.
+export interface StoreContext {
+  store: NormalizedCache;
+  fragmentMap: FragmentMap;
+}
+
 export function diffQueryAgainstStore({
   store,
   query,
@@ -54,7 +61,7 @@ export function diffQueryAgainstStore({
   const queryDef = getQueryDefinition(query);
 
   return diffSelectionSetAgainstStore({
-    store,
+    context: { store, fragmentMap: {} },
     rootId: 'ROOT_QUERY',
     selectionSet: queryDef.selectionSet,
     throwOnMissingField: false,
@@ -76,7 +83,7 @@ export function diffFragmentAgainstStore({
   const fragmentDef = getFragmentDefinition(fragment);
 
   return diffSelectionSetAgainstStore({
-    store,
+    context: { store, fragmentMap: {} },
     rootId,
     selectionSet: fragmentDef.selectionSet,
     throwOnMissingField: false,
@@ -96,28 +103,22 @@ export function diffFragmentAgainstStore({
  * @return {result: Object, missingSelectionSets: [SelectionSet]}
  */
 export function diffSelectionSetAgainstStore({
+  context,
   selectionSet,
-  store,
   rootId,
   throwOnMissingField = false,
   variables,
-  fragmentMap,
 }: {
+  context: StoreContext,
   selectionSet: SelectionSet,
-  store: NormalizedCache,
   rootId: string,
   throwOnMissingField: boolean,
   variables: Object,
-  fragmentMap?: FragmentMap,
 }): DiffResult {
   if (selectionSet.kind !== 'SelectionSet') {
     throw new Error('Must be a selection set.');
   }
 
-  if (!fragmentMap) {
-    fragmentMap = {};
-  }
-
   const result = {};
   const missingFields: Selection[] = [];
 
@@ -138,12 +139,11 @@ export function diffSelectionSetAgainstStore({
           result: fieldResult,
           isMissing: fieldIsMissing,
         } = diffFieldAgainstStore({
+          context,
           field: selection,
           throwOnMissingField,
           variables,
           rootId,
-          store,
-          fragmentMap,
           included: includeField,
         });
 
@@ -162,12 +162,11 @@ export function diffSelectionSetAgainstStore({
         result: fieldResult,
         isMissing: fieldIsMissing,
       } = diffSelectionSetAgainstStore({
+        context,
         selectionSet: selection.selectionSet,
         throwOnMissingField,
         variables,
         rootId,
-        store,
-        fragmentMap,
       });
 
       if (fieldIsMissing) {
@@ -176,7 +175,7 @@ export function diffSelectionSetAgainstStore({
         assign(result, fieldResult);
       }
     } else {
-      const fragment = fragmentMap[selection.name.value];
+      const fragment = context.fragmentMap[selection.name.value];
       if (!fragment) {
         throw new Error(`No fragment named ${selection.name.value}`);
       }
@@ -185,12 +184,11 @@ export function diffSelectionSetAgainstStore({
         result: fieldResult,
         isMissing: fieldIsMissing,
       } = diffSelectionSetAgainstStore({
+        context,
         selectionSet: fragment.selectionSet,
         throwOnMissingField,
         variables,
         rootId,
-        store,
-        fragmentMap,
       });
 
       if (fieldIsMissing) {
@@ -235,23 +233,21 @@ export function diffSelectionSetAgainstStore({
 }
 
 function diffFieldAgainstStore({
+  context,
   field,
   throwOnMissingField,
   variables,
   rootId,
-  store,
-  fragmentMap,
   included = true,
 }: {
+  context: StoreContext,
   field: Field,
   throwOnMissingField: boolean,
   variables: Object,
   rootId: string,
-  store: NormalizedCache,
-  fragmentMap?: FragmentMap,
   included?: Boolean,
 }): FieldDiffResult {
-  const storeObj = store[rootId] || {};
+  const storeObj = context.store[rootId] || {};
   const storeFieldKey = storeKeyNameFromField(field, variables);
 
   if (! has(storeObj, storeFieldKey)) {
@@ -293,12 +289,11 @@ Perhaps you want to use the \`returnPartialData\` option?`);
       }
 
       const itemDiffResult = diffSelectionSetAgainstStore({
-        store,
+        context,
         throwOnMissingField,
         rootId: id,
         selectionSet: field.selectionSet,
         variables,
-        fragmentMap,
       });
 
       if (itemDiffResult.isMissing) {
@@ -317,12 +312,11 @@ Perhaps you want to use the \`returnPartialData\` option?`);
 
   if (isString(storeValue)) {
     return diffSelectionSetAgainstStore({
-      store,
+      context,
       throwOnMissingField,
       rootId: storeValue,
       selectionSet: field.selectionSet,
       variables,
-      fragmentMap,
     });
   }
 

src/data/readFromStore.ts

@@ -1,5 +1,6 @@
 import {
   diffSelectionSetAgainstStore,
+  StoreContext,
 } from './diffAgainstStore';
 
 import {
@@ -10,7 +11,6 @@ import {
 import {
   getQueryDefinition,
   getFragmentDefinition,
-  FragmentMap,
 } from '../queries/getFromAST';
 
 import {
@@ -35,7 +35,7 @@ export function readQueryFromStore({
   const queryDef = getQueryDefinition(query);
 
   return readSelectionSetFromStore({
-    store,
+    context: { store, fragmentMap: {} },
     rootId: 'ROOT_QUERY',
     selectionSet: queryDef.selectionSet,
     variables,
@@ -59,7 +59,7 @@ export function readFragmentFromStore({
   const fragmentDef = getFragmentDefinition(fragment);
 
   return readSelectionSetFromStore({
-    store,
+    context: { store, fragmentMap: {} },
     rootId,
     selectionSet: fragmentDef.selectionSet,
     variables,
@@ -68,29 +68,26 @@ export function readFragmentFromStore({
 }
 
 export function readSelectionSetFromStore({
-  store,
+  context,
   rootId,
   selectionSet,
   variables,
   returnPartialData = false,
-  fragmentMap,
 }: {
-  store: NormalizedCache,
+  context: StoreContext,
   rootId: string,
   selectionSet: SelectionSet,
   variables: Object,
   returnPartialData?: boolean,
-  fragmentMap?: FragmentMap,
 }): Object {
   const {
     result,
   } = diffSelectionSetAgainstStore({
+    context,
     selectionSet,
     rootId,
-    store,
     throwOnMissingField: !returnPartialData,
     variables,
-    fragmentMap,
   });
 
   return result;

test/diffAgainstStore.ts

@@ -319,7 +319,7 @@ describe('diffing queries against the store', () => {
     `;
 
     const { result } = diffSelectionSetAgainstStore({
-      store,
+      context: { store, fragmentMap: {} },
       rootId: 'ROOT_QUERY',
       selectionSet: getQueryDefinition(queryWithMissingField).selectionSet,
       variables: null,
@@ -333,7 +333,7 @@ describe('diffing queries against the store', () => {
     });
     assert.throws(function() {
       diffSelectionSetAgainstStore({
-        store,
+        context: { store, fragmentMap: {} },
         rootId: 'ROOT_QUERY',
         selectionSet: getQueryDefinition(queryWithMissingField).selectionSet,
         variables: null,