From 908a4eb6436e5b616c11cce43a605f30cf2c0b28 Mon Sep 17 00:00:00 2001
From: Marco129 <marco.website01@gmail.com>
Date: Sun, 6 Mar 2016 17:22:36 +0800
Subject: [PATCH] Fix delete relation field when _Join collection not exist

---
 spec/Schema.spec.js | 32 ++++++++++++++++++++++++++++++++
 src/Schema.js       |  6 +++++-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/spec/Schema.spec.js b/spec/Schema.spec.js
index 62ce711ef6..6ab08d6abf 100644
--- a/spec/Schema.spec.js
+++ b/spec/Schema.spec.js
@@ -577,6 +577,38 @@ describe('Schema', () => {
       });
   });
 
+  it('can delete relation field when related _Join collection not exist', done => {
+    config.database.loadSchema()
+    .then(schema => {
+      schema.addClassIfNotExists('NewClass', {
+        relationField: {type: 'Relation', targetClass: '_User'}
+      })
+      .then(mongoObj => {
+        expect(mongoObj).toEqual({
+          _id: 'NewClass',
+          objectId: 'string',
+          updatedAt: 'string',
+          createdAt: 'string',
+          relationField: 'relation<_User>',
+        });
+      })
+      .then(() => config.database.collectionExists('_Join:relationField:NewClass'))
+      .then(exist => {
+        expect(exist).toEqual(false);
+      })
+      .then(() => schema.deleteField('relationField', 'NewClass', config.database))
+      .then(() => schema.reloadData())
+      .then(() => {
+        expect(schema['data']['NewClass']).toEqual({
+          objectId: 'string',
+          updatedAt: 'string',
+          createdAt: 'string'
+        });
+        done();
+      });
+    });
+  });
+
   it('can delete string fields and resave as number field', done => {
     Parse.Object.disableSingleInstance();
     var obj1 = hasAllPODobject();
diff --git a/src/Schema.js b/src/Schema.js
index 73eaa3254b..0ed5552792 100644
--- a/src/Schema.js
+++ b/src/Schema.js
@@ -409,7 +409,11 @@ class Schema {
 
             if (this.data[className][fieldName].startsWith('relation<')) {
               //For relations, drop the _Join table
-              return database.dropCollection(`_Join:${fieldName}:${className}`);
+              return database.collectionExists(`_Join:${fieldName}:${className}`).then(exist => {
+                if (exist) {
+                  return database.dropCollection(`_Join:${fieldName}:${className}`);
+                }
+              });
             }
 
             // for non-relations, remove all the data.