fix(document): support validators on nested arrays

Fix #7926

lib/document.js

@@ -1988,10 +1988,18 @@ function _getPathsToValidate(doc) {
     }
 
     const val = doc.$__getValue(path);
-    if (val) {
+    _pushNestedArrayPaths(val, paths, path);
+  }
+
+  function _pushNestedArrayPaths(val, paths, path) {
+    if (val != null) {
       const numElements = val.length;
       for (let j = 0; j < numElements; ++j) {
-        paths.push(path + '.' + j);
+        if (Array.isArray(val[j])) {
+          _pushNestedArrayPaths(val[j], paths, path + '.' + j);
+        } else {
+          paths.push(path + '.' + j);
+        }
       }
     }
   }

lib/schema.js

@@ -1126,6 +1126,10 @@ function getPositionalPathType(self, path) {
 
     // ignore if its just a position segment: path.0.subpath
     if (!/\D/.test(subpath)) {
+      // Nested array
+      if (val instanceof MongooseTypes.Array && i !== last) {
+        val = val.caster;
+      }
       continue;
     }
 

lib/schema/array.js

@@ -205,11 +205,19 @@ SchemaArray.prototype.checkRequired = function checkRequired(value, doc) {
  */
 
 SchemaArray.prototype.enum = function() {
-  const instance = get(this, 'caster.instance');
-  if (instance !== 'String') {
-    throw new Error('`enum` can only be set on an array of strings, not ' + instance);
+  let arr = this; /* eslint consistent-this: 0 */
+  while (true) { /* eslint no-constant-condition: 0 */
+    const instance = get(arr, 'caster.instance');
+    if (instance === 'Array') {
+      arr = arr.caster;
+      continue;
+    }
+    if (instance !== 'String') {
+      throw new Error('`enum` can only be set on an array of strings, not ' + instance);
+    }
+    break;
   }
-  this.caster.enum.apply(this.caster, arguments);
+  arr.caster.enum.apply(arr.caster, arguments);
   return this;
 };
 

test/document.test.js

@@ -7841,4 +7841,22 @@ describe('document', function() {
       assert.ok(doc.testDecimal instanceof mongoose.Types.Decimal128);
     });
   });
+
+  it('allows enum on array of array of strings (gh-7926)', function() {
+    const schema = new Schema({
+      test: {
+        type: [[String]],
+        enum: ['bar']
+      }
+    });
+
+    const Model = db.model('gh7926', schema);
+
+    return Model.create({ test: [['foo']] }).then(() => assert.ok(false), err => {
+      assert.ok(err);
+      assert.ok(err.errors['test.0.0']);
+      assert.ok(err.errors['test.0.0'].message.indexOf('foo') !== -1,
+        err.errors['test.0.0'].message);
+    });
+  });
 });