Merge pull request #14769 from Automattic/vkarpov15/gh-6691-2

fix: allow setting document array default to `null`

Author: vkarpov15

lib/schema/documentArray.js

@@ -69,7 +69,7 @@ function SchemaDocumentArray(key, schema, options, schemaOptions) {
 
   const fn = this.defaultValue;
 
-  if (!('defaultValue' in this) || fn !== void 0) {
+  if (!('defaultValue' in this) || fn != null) {
     this.default(function() {
       let arr = fn.call(this);
       if (arr != null && !Array.isArray(arr)) {

test/document.test.js

@@ -3203,16 +3203,22 @@ describe('document', function() {
         names: {
           type: [String],
           default: null
+        },
+        tags: {
+          type: [{ tag: String }],
+          default: null
         }
       });
 
       const Model = db.model('Test', schema);
       const m = new Model();
       assert.strictEqual(m.names, null);
+      assert.strictEqual(m.tags, null);
       await m.save();
 
       const doc = await Model.collection.findOne({ _id: m._id });
       assert.strictEqual(doc.names, null);
+      assert.strictEqual(doc.tags, null);
     });
 
     it('validation works when setting array index (gh-3816)', async function() {