[BUGFIX identifiers] Address issue with polymorphic findRecord

packages/-ember-data/tests/integration/identifiers/polymorphic-scenarios-test.ts

@@ -61,7 +61,34 @@ module('Integration | Identifiers - single-table-inheritance polymorphic scenari
       store = owner.lookup('service:store');
     });
 
-    test(`Identity of polymorphic relations can change type`, async function(assert) {
+    test(`Identity of polymorphic relations can change type on first load`, async function(assert) {
+      const { owner } = this;
+      class TestAdapter extends Adapter {
+        shouldBackgroundReloadRecord() {
+          return false;
+        }
+        findRecord(_, __, id) {
+          return resolve({
+            data: {
+              id,
+              type: 'ferrari',
+              attributes: {
+                color: 'red',
+              },
+            },
+          });
+        }
+      }
+      owner.register('adapter:application', TestAdapter);
+
+      const foundFerrari = await store.findRecord('car', '1');
+      assert.strictEqual(foundFerrari.constructor.modelName, 'ferrari', 'We found the right type');
+
+      const cachedFerrari = await store.peekRecord('ferrari', '1');
+      assert.strictEqual(cachedFerrari.constructor.modelName, 'ferrari', 'We cached the right type');
+    });
+
+    test(`Identity of polymorphic relations can change type when in cache`, async function(assert) {
       const { owner } = this;
       const requests: RID[] = [];
       const expectedRequests = [

packages/store/addon/-private/system/core-store.ts

@@ -1198,7 +1198,8 @@ abstract class CoreStore extends Service {
     return promise.then(
       payload => {
         // ensure that regardless of id returned we assign to the correct record
-        if (payload.data && !Array.isArray(payload.data)) {
+        // for polymorphic, if type does not match, we'll need a new identifier
+        if (payload.data && !Array.isArray(payload.data) && payload.data.type === identifier.type) {
           payload.data.lid = identifier.lid;
         }
 

packages/store/addon/-private/system/store/finders.js

@@ -59,7 +59,10 @@ export function _find(adapter, store, modelClass, id, internalModel, options) {
       );
 
       // ensure that regardless of id returned we assign to the correct record
-      payload.data.lid = identifier.lid;
+      // for polymorphic, if type does not match, we'll need a new identifier
+      if (payload.data.type === identifier.type) {
+        payload.data.lid = identifier.lid;
+      }
 
       return store._push(payload);
     },