Fix #1919 (#1926)

spec/schemas.spec.js

@@ -1556,4 +1556,21 @@ describe('schemas', () => {
       done();
     })
   })
+
+  it('gives correct response when deleting a schema with CLPs (regression test #1919)', done => {
+    new Parse.Object('MyClass').save({ data: 'foo'})
+    .then(obj => obj.destroy())
+    .then(() => setPermissionsOnClass('MyClass', { find: {}, get: {} }, true))
+    .then(() => {
+      request.del({
+        url: 'http://localhost:8378/1/schemas/MyClass',
+        headers: masterKeyHeaders,
+        json: true,
+      }, (error, response, body) => {
+        expect(response.statusCode).toEqual(200);
+        expect(response.body).toEqual({});
+        done();
+      });
+    });
+  });
 });

src/Routers/SchemasRouter.js

@@ -67,7 +67,7 @@ function modifySchema(req) {
 // A helper function that removes all join tables for a schema. Returns a promise.
 var removeJoinTables = (database, mongoSchema) => {
   return Promise.all(Object.keys(mongoSchema)
-    .filter(field => mongoSchema[field].startsWith('relation<'))
+    .filter(field => field !== '_metadata' && mongoSchema[field].startsWith('relation<'))
     .map(field => {
       let collectionName = `_Join:${field}:${mongoSchema._id}`;
       return database.adapter.deleteOneSchema(collectionName);