[BUGFIX] serialize null array items to string (#8083)

packages/-ember-data/tests/unit/utils/serialize-query-params-test.js

@@ -0,0 +1,53 @@
+import { module, test } from 'qunit';
+
+import { serializeQueryParams } from '@ember-data/adapter/-private';
+
+module('Unit | serializeQueryParams', function () {
+  test('it works', function (assert) {
+    assert.expect(1);
+
+    const qp = {
+      filter: '%foo',
+    };
+    const result = serializeQueryParams(qp);
+
+    assert.deepEqual(result, 'filter=%25foo');
+  });
+
+  test('it works with nested', function (assert) {
+    assert.expect(1);
+
+    const qp = {
+      filter: {
+        children: [1, 2],
+      },
+    };
+    const result = serializeQueryParams(qp);
+
+    assert.deepEqual(result, 'filter%5Bchildren%5D%5B%5D=1&filter%5Bchildren%5D%5B%5D=2');
+  });
+
+  test('it treats null values in arrays as empty strings', function (assert) {
+    assert.expect(1);
+
+    const qp = {
+      filter: {
+        children: [null, 2],
+      },
+    };
+    const result = serializeQueryParams(qp);
+
+    assert.deepEqual(result, 'filter%5Bchildren%5D%5B%5D=&filter%5Bchildren%5D%5B%5D=2');
+  });
+
+  test('it works with + sign', function (assert) {
+    assert.expect(1);
+
+    const qp = {
+      term: 'search me',
+    };
+    const result = serializeQueryParams(qp);
+
+    assert.deepEqual(result, 'term=search%20me');
+  });
+});

packages/adapter/addon/-private/utils/serialize-query-params.ts

@@ -19,7 +19,7 @@ export function serializeQueryParams(queryParamsObject: object | string): string
           if (RBRACKET.test(prefix)) {
             add(s, prefix, obj[i]);
           } else {
-            buildParams(prefix + '[' + (typeof obj[i] === 'object' ? i : '') + ']', obj[i]);
+            buildParams(prefix + '[' + (typeof obj[i] === 'object' && obj[i] !== null ? i : '') + ']', obj[i]);
           }
         }
       } else if (isPlainObject(obj)) {