From f759486307e4e54f964b3c6e2ce019604bee5553 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Sat, 10 Feb 2018 00:35:58 +0100
Subject: [PATCH] type inferring - handle array of Date objects (#3955)

* inferring types: handle array of Date objects

* add tests for inferring arrays of Date objects
---
 .../infer-graphql-type-test.js.snap           | 22 ++++++++++++++++++-
 .../__tests__/infer-graphql-type-test.js      | 20 ++++++++++++++++-
 packages/gatsby/src/schema/data-tree-utils.js |  6 +++--
 .../src/schema/infer-graphql-input-fields.js  |  2 ++
 4 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/packages/gatsby/src/schema/__tests__/__snapshots__/infer-graphql-type-test.js.snap b/packages/gatsby/src/schema/__tests__/__snapshots__/infer-graphql-type-test.js.snap
index f3fb4e067e9cc..a41450342d450 100644
--- a/packages/gatsby/src/schema/__tests__/__snapshots__/infer-graphql-type-test.js.snap
+++ b/packages/gatsby/src/schema/__tests__/__snapshots__/infer-graphql-type-test.js.snap
@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`GraphQL type inferance Handles dates Date type inference 1`] = `
+exports[`GraphQL type inferance Handles dates Infers from Date objects 1`] = `
 Object {
   "data": Object {
     "listNode": Array [
@@ -15,6 +15,26 @@ Object {
 }
 `;
 
+exports[`GraphQL type inferance Handles dates Infers from array of Date objects 1`] = `
+Object {
+  "data": Object {
+    "listNode": Array [
+      Object {
+        "dateObject": Array [
+          "2012-11-05T00:00:00.000Z",
+          "2012-11-06T00:00:00.000Z",
+        ],
+      },
+      Object {
+        "dateObject": Array [
+          "2012-11-05T00:00:00.000Z",
+        ],
+      },
+    ],
+  },
+}
+`;
+
 exports[`GraphQL type inferance Infers graphql type from array of nodes 1`] = `
 Object {
   "data": Object {
diff --git a/packages/gatsby/src/schema/__tests__/infer-graphql-type-test.js b/packages/gatsby/src/schema/__tests__/infer-graphql-type-test.js
index b6c3f7002bb1d..d20325ae4fb47 100644
--- a/packages/gatsby/src/schema/__tests__/infer-graphql-type-test.js
+++ b/packages/gatsby/src/schema/__tests__/infer-graphql-type-test.js
@@ -199,7 +199,7 @@ describe(`GraphQL type inferance`, () => {
       expect(result.data.listNode[0].number).toEqual(2018)
     })
 
-    it(`Date type inference`, async () => {
+    it(`Infers from Date objects`, async () => {
       let result = await queryResult(
         [
           { dateObject: new Date(Date.UTC(2012, 10, 5)) },
@@ -212,6 +212,24 @@ describe(`GraphQL type inferance`, () => {
       expect(result).toMatchSnapshot()
     })
 
+    it(`Infers from array of Date objects`, async () => {
+      let result = await queryResult(
+        [
+          {
+            dateObject: [
+              new Date(Date.UTC(2012, 10, 5)),
+              new Date(Date.UTC(2012, 10, 6)),
+            ],
+          },
+          { dateObject: [new Date(Date.UTC(2012, 10, 5))] },
+        ],
+        `
+          dateObject
+        `
+      )
+      expect(result).toMatchSnapshot()
+    })
+
     it(`Infers from date strings`, async () => {
       let result = await queryResult(
         [{ date: `1012-11-01` }],
diff --git a/packages/gatsby/src/schema/data-tree-utils.js b/packages/gatsby/src/schema/data-tree-utils.js
index ec8ab5f8ee9d6..601a4c46cdf6a 100644
--- a/packages/gatsby/src/schema/data-tree-utils.js
+++ b/packages/gatsby/src/schema/data-tree-utils.js
@@ -83,8 +83,10 @@ const extractFieldExamples = (nodes: any[]) =>
         return array
       }
 
-      // primitive values don't get merged further, just take the first item
-      if (!_.isObject(array[0])) return array.slice(0, 1)
+      // primitive values and dates don't get merged further, just take the first item
+      if (!_.isObject(array[0]) || array[0] instanceof Date) {
+        return array.slice(0, 1)
+      }
       let merged = extractFieldExamples(array)
       return isDefined(merged) ? [merged] : null
     }
diff --git a/packages/gatsby/src/schema/infer-graphql-input-fields.js b/packages/gatsby/src/schema/infer-graphql-input-fields.js
index d1c55c471a3fb..2e4aaa3c9189b 100644
--- a/packages/gatsby/src/schema/infer-graphql-input-fields.js
+++ b/packages/gatsby/src/schema/infer-graphql-input-fields.js
@@ -79,6 +79,7 @@ function inferGraphQLInputFields({
         case `float`:
           inType = GraphQLFloat
           break
+        case `date`:
         case `string`:
           inType = GraphQLString
           break
@@ -129,6 +130,7 @@ function inferGraphQLInputFields({
         }),
       }
     }
+    case `date`:
     case `string`: {
       return {
         type: new GraphQLInputObjectType({