From 28c7524e006a0d5178b5eb80bdac38f246e56cc7 Mon Sep 17 00:00:00 2001
From: bquinn <bquinn@vrbo.com>
Date: Mon, 28 Sep 2020 08:45:34 -0700
Subject: [PATCH] consider the so-far-traversed path (instead of individual
 segments) when checking for null when merging errors

---
 lib/delegate/__tests__.js | 72 ++++++++++++++++++++++++++++++++++++++-
 lib/delegate/index.js     | 13 +++----
 package.json              |  1 +
 3 files changed, 79 insertions(+), 7 deletions(-)

diff --git a/lib/delegate/__tests__.js b/lib/delegate/__tests__.js
index e902dbf..8205d1d 100644
--- a/lib/delegate/__tests__.js
+++ b/lib/delegate/__tests__.js
@@ -1364,7 +1364,7 @@ Test('delegateToComponent - target field non-nullable arg is not passed', async
   t.end();
 });
 
-Test('delegateToComponent - with errors', async (t) => {
+Test('delegateToComponent - with errors (selection set order doesnt matter)', async (t) => {
   const primitive = new GraphQLComponent({
     types: `
       type Query {
@@ -1509,6 +1509,76 @@ Test('delegateToComponent - with errors - delegate graphql data result is comple
   t.equal(result.data.bar, null, 'query resolves as expected');
   t.equal(result.errors.length, 1, '1 error returned');
   t.equal(result.errors[0].message, 'Cannot return null for non-nullable field Foo.b.', 'expected error is propagated regardless of completely null delegate result');
+  t.deepEqual(result.errors[0].path, ['foo', 'b']);
   t.end();
 });
 
+Test('delegateToComponent - errors merged as expected for non-nullable list that allows nullable items', async (t) => {
+  const primitive = new GraphQLComponent({
+    types: `
+      type Query {
+        foos: [Foo]!
+      }
+
+      type Foo {
+        a: String!
+      }
+    `,
+    resolvers: {
+      Query: {
+        foos() {
+          return [ { a: 'bar'} , {}, { a: 'baz'} ];
+        }
+      }
+    }
+  });
+
+  const composite = new GraphQLComponent({
+    types: `
+      type Query {
+        bar: Bar
+      }
+
+      type Bar {
+        foos: [Foo]!
+      }
+    `,
+    resolvers: {
+      Query: {
+        async bar(_root, _args, context, info) {
+          const foos = await GraphQLComponent.delegateToComponent(primitive, {
+            info,
+            contextValue: context,
+            targetRootField: 'foos',
+            subPath: 'foos'
+          });
+          return { foos };
+        }
+      }
+    },
+    imports: [primitive]
+  });
+
+  const document = gql`
+    query {
+      bar {
+        foos {
+          a
+        }
+      }
+    }
+  `;
+
+  const result = await graphql.execute({
+    document,
+    schema: composite.schema,
+    contextValue: {}
+  });
+
+  t.deepEqual(result.data.bar.foos[0], { a: 'bar' }, 'first item of list resolved as expected');
+  t.deepEqual(result.data.bar.foos[2], { a: 'baz' }, 'third item of list resolved as expected');
+  t.equal(result.errors.length, 1, 'one error returned');
+  t.equal(result.errors[0].message, 'Cannot return null for non-nullable field Foo.a.');
+  t.deepEqual(result.errors[0].path, ['foos', 1, 'a']);
+  t.end();
+});
\ No newline at end of file
diff --git a/lib/delegate/index.js b/lib/delegate/index.js
index 02cb9aa..4a92906 100644
--- a/lib/delegate/index.js
+++ b/lib/delegate/index.js
@@ -12,7 +12,8 @@ const {
   visit,
   visitWithTypeInfo
 } = require('graphql');
-const deepSet = require('lodash.set');
+const set = require('lodash.set');
+const get = require('lodash.get');
 const debug = require('debug')('graphql-component:delegate');
 
 /**
@@ -195,14 +196,14 @@ const createSubOperationDocument = function (component, targetRootField, args, s
 const mergeErrors = function (data, errors) {
   for (const error of errors) {
     const { path } = error;
-    const mergePath = [];
-    for (const segment of path) {
-      mergePath.push(segment);
-      if (!data[segment]) {
+    let depth = 1;
+    while (depth <= path.length) {
+      if (!get(data, path.slice(0, depth))) {
         break;
       }
+      depth++;
     }
-    deepSet(data, mergePath, error);
+    set(data, path.slice(0, depth), error);
   }
 }
 
diff --git a/package.json b/package.json
index 772bda8..01737fd 100644
--- a/package.json
+++ b/package.json
@@ -25,6 +25,7 @@
     "cuid": "^2.1.8",
     "debug": "^4.1.1",
     "graphql-tools": "^6.0.10",
+    "lodash.get": "^4.4.2",
     "lodash.set": "^4.3.2"
   },
   "peerDependencies": {