I want to compare two relations on a ParseObject, and decide if they are equal, preferably without calling fetch() on the relations. I have tried doing this:
MyParseObject.Get<ParseObject>("MyRelation") == MyOtherParseObject.Get<ParseObject>("MyRelation")
But it doesn't work. I have tried searching around google, but hasn't found an answer to my question. Is it possible to compare these relations, without fetching their data?
Any help would be greatly appreciated. Thank you.
I haven't used this before, but figured I'd take a look at the documentation and code anyway.
The comment on the ObjectId property states the criteria for determining whether two ParseObject instances are considered equal:
The combination of a Parse.ParseObject.ClassName and an Parse.ParseObject.ObjectId uniquely identifies an object in your application.
So if the ClassName and ObjectId properties are equal, the two instances are equal:
var my1 = MyParseObject.Get<ParseObject>("MyRelation");
var my2 = MyOtherParseObject.Get<ParseObject>("MyRelation");
return my1.ObjectId == my2.ObjectId && my1.ClassName == my2.ClassName;
But instead of having to do that manually, you found the method they provided that does it for you:
return MyParseObject.Get<ParseObject>("MyRelation")
.HasSameId(MyOtherParseObject.Get<ParseObject>("MyRelation"));
From the HasSameId documentation:
A helper function for checking whether two ParseObjects point to the same object in the cloud.
Here's what it's doing internally (there's other stuff too, but this is the comparison part):
return other != null
&& object.Equals((object) this.ClassName, (object) other.ClassName)
&& object.Equals((object) this.ObjectId, (object) other.ObjectId);
A note about your original code that was using the == sign...
If the ParseObject class had overloaded the == operator and specified that it should compare the ClassName and ObjectId, then your original code would have worked.
Since they didn't overload that operator, and the default behavior of the == operator is to do a reference comparison, and MyParseObject.Get<ParseObject> and MyOtherParseObject.Get<ParseObject> are technically two different objects, it returned false.
Nevermind, I have found my answer. The statement below worked fine.
MyParseObject.Get<ParseObject>("MyRelation").HasSameId(MyOtherParseObject.Get<ParseObject>("MyRelation"))