From dc0928e3c80330ec70d3d65e8385404942242b61 Mon Sep 17 00:00:00 2001
From: "David J. Hamilton" <dhamilton@linkedin.com>
Date: Thu, 29 Nov 2018 17:56:16 -0800
Subject: [PATCH] [BUGFIX beta] backport #5767 Make _recordData lazy

---
 addon/-private/system/model/internal-model.js | 21 ++++++-
 tests/integration/records/record-data-test.js | 59 +++++++++++++++++++
 2 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/addon/-private/system/model/internal-model.js b/addon/-private/system/model/internal-model.js
index af126b1117c..968ae91105e 100644
--- a/addon/-private/system/model/internal-model.js
+++ b/addon/-private/system/model/internal-model.js
@@ -92,7 +92,7 @@ export default class InternalModel {
     this.modelName = modelName;
     this.clientId = clientId;
 
-    this._recordData = store._createRecordData(modelName, id, clientId, this);
+    this.__recordData = null;
 
     // this ensure ordered set can quickly identify this as unique
     this[Ember.GUID_KEY] = InternalModelReferenceId++ + 'internal-model';
@@ -143,6 +143,17 @@ export default class InternalModel {
     return this._recordReference;
   }
 
+  get _recordData() {
+    if (this.__recordData === null) {
+      this._recordData = this.store._createRecordData(this.modelName, this.id, this.clientId, this);
+    }
+    return this.__recordData;
+  }
+
+  set _recordData(newValue) {
+    this.__recordData = newValue;
+  }
+
   get _recordArrays() {
     if (this.__recordArrays === null) {
       this.__recordArrays = new OrderedSet();
@@ -790,6 +801,10 @@ export default class InternalModel {
 
   hasChangedAttributes() {
     heimdall.increment(hasChangedAttributes);
+    if (this.isLoading() && !this.isReloading) {
+      // no need to instantiate _recordData in this case
+      return false;
+    }
     return this._recordData.hasChangedAttributes();
   }
 
@@ -802,6 +817,10 @@ export default class InternalModel {
   */
   changedAttributes() {
     heimdall.increment(changedAttributes);
+    if (this.isLoading() && !this.isReloading) {
+      // no need to calculate changed attributes when calling `findRecord`
+      return {};
+    }
     return this._recordData.changedAttributes();
   }
 
diff --git a/tests/integration/records/record-data-test.js b/tests/integration/records/record-data-test.js
index a9b9c3f9765..2106494c4cc 100644
--- a/tests/integration/records/record-data-test.js
+++ b/tests/integration/records/record-data-test.js
@@ -5,6 +5,7 @@ import { run } from '@ember/runloop';
 import { attr, belongsTo, hasMany } from '@ember-decorators/data';
 import { assign } from '@ember/polyfills';
 import { RecordData } from 'ember-data/-private';
+import { resolve } from 'rsvp';
 
 class Person extends Model {
   @hasMany('pet', { inverse: null, async: false })
@@ -230,4 +231,62 @@ module('RecordData Compatibility', function(hooks) {
       assert.ok(false, 'expected `unloadRecord()` not to throw');
     }
   });
+
+  test(`store.findRecord does not eagerly instantiate record data`, async function(assert) {
+    let recordDataInstances = 0;
+    class TestRecordData extends CustomRecordData {
+      constructor() {
+        super(...arguments);
+        ++recordDataInstances;
+      }
+    }
+
+    store.createRecordDataFor = function(modelName, id, lid, storeWrapper) {
+      return new TestRecordData(modelName, id, lid, storeWrapper);
+    };
+    this.owner.register(
+      'adapter:pet',
+      class TestAdapter {
+        static create() {
+          return new TestAdapter(...arguments);
+        }
+
+        findRecord() {
+          assert.equal(
+            recordDataInstances,
+            0,
+            'no instance created from findRecord before adapter promise resolves'
+          );
+
+          return resolve({
+            data: {
+              id: '1',
+              type: 'pet',
+              attributes: {
+                name: 'Loki',
+              },
+            },
+          });
+        }
+      }
+    );
+    this.owner.register(
+      'serializer:pet',
+      class TestSerializer {
+        static create() {
+          return new TestSerializer(...arguments);
+        }
+
+        normalizeResponse(store, modelClass, payload) {
+          return payload;
+        }
+      }
+    );
+
+    assert.equal(recordDataInstances, 0, 'initially no instances');
+
+    await store.findRecord('pet', '1');
+
+    assert.equal(recordDataInstances, 1, 'record data created after promise fulfills');
+  });
 });