feat: allow rewriters to modify parent result (#22)

* feat: allow rewriters to modify parent result

BREAKING CHANGE: Changes the behavior of `Rewriter`.`rewriteResponse` so that implementations modify the parent result instead of only returning the result of the key path.

* refactor: remove direct mutation of rewritten responses

* fix: use previous logic for rewriting array children

Author: gregbty

src/ast.ts

@@ -275,11 +275,11 @@ export const rewriteResultsAtPath = (
         const newValue = callback(curResults, index);
         return newValue;
       });
-    } else {
-      newResults[curPathElm] = callback(results, curPathElm);
+
+      return newResults;
     }
 
-    return newResults;
+    return callback(results, curPathElm);
   }
 
   const remainingPath = path.slice(1);

src/rewriters/NestFieldOutputsRewriter.ts

@@ -66,7 +66,7 @@ class NestFieldOutputsRewriter extends Rewriter {
   }
 
   public rewriteResponse(response: any, key: string | number) {
-    const pathResponse = super.rewriteResponse(response, key);
+    const pathResponse = response[key];
 
     if (typeof pathResponse === 'object') {
       // undo the nesting in the response so it matches the original query
@@ -76,10 +76,15 @@ class NestFieldOutputsRewriter extends Rewriter {
       ) {
         const rewrittenResponse = { ...pathResponse, ...pathResponse[this.newOutputName] };
         delete rewrittenResponse[this.newOutputName];
-        return rewrittenResponse;
+
+        return {
+          ...response,
+          [key]: rewrittenResponse
+        };
       }
     }
-    return pathResponse;
+
+    return response;
   }
 }
 

src/rewriters/Rewriter.ts

@@ -57,7 +57,7 @@ abstract class Rewriter {
   }
 
   public rewriteResponse(response: any, key: string | number): any {
-    return response[key];
+    return response;
   }
 }
 

src/rewriters/ScalarFieldToObjectFieldRewriter.ts

@@ -49,14 +49,17 @@ class ScalarFieldToObjectFieldRewriter extends Rewriter {
   }
 
   public rewriteResponse(response: any, key: string | number) {
-    const pathResponse = super.rewriteResponse(response, key);
-
     if (typeof response === 'object') {
+      const pathResponse = response[key];
+
       // undo the nesting in the response so it matches the original query
-      return pathResponse[this.objectFieldName];
+      return {
+        ...response,
+        [key]: pathResponse[this.objectFieldName]
+      };
     }
 
-    return pathResponse;
+    return response;
   }
 }
 

test/ast.test.ts

@@ -17,7 +17,10 @@ describe('ast utils', () => {
         }
       };
       expect(
-        rewriteResultsAtPath(obj, ['thing1', 'moreThings', 'type'], (elm, path) => elm[path] + '!')
+        rewriteResultsAtPath(obj, ['thing1', 'moreThings', 'type'], (elm, path) => ({
+          ...elm,
+          [path]: elm[path] + '!'
+        }))
       ).toEqual({
         thing1: {
           moreThings: [{ type: 'dog!' }, { type: 'cat!' }, { type: 'lion!' }]
@@ -50,7 +53,10 @@ describe('ast utils', () => {
         ]
       };
       expect(
-        rewriteResultsAtPath(obj, ['things', 'moreThings', 'type'], (elm, path) => elm[path] + '!')
+        rewriteResultsAtPath(obj, ['things', 'moreThings', 'type'], (elm, path) => ({
+          ...elm,
+          [path]: elm[path] + '!'
+        }))
       ).toEqual({
         things: [
           {