Update/Delete a sub document in mongodb using C# driver

Question

I have 2 classes:

public class Vote
{
    public string VoteId { get; set; }
    public string Question { get; set; }
    public List<VoteAnswer> AnswerList { get; set; }
}

And:

public class VoteOption
{
    public string OptionId { get; set; }
    public string OptionName { get; set; }
    public double VoteCount { get; set; }
}

How can i update/delete a VoteOption in a Vote where VoteId = voteId and OptionId = optionId? Using C# driver.

First I get VoteOption by:

        var v = col.FindOneAs<Vote>(Query.EQ("VoteID", voteId));
        VoteOption vo = v.AnswerList.Find(x => x.OptionId == optionId);

End set some value to it:

vo.OptionName = "some option chose";
vo.VoteCount = 1000;

But i don't know what next step to update this vo to Vote parent.

And, if i want to delete this vo, show me that way!

Data in MongoDB like that:

{
  "_id" : "460b3a7ff100",
  "Question" : "this is question?",
  "AnswerList" : [{
      "OptionId" : "1",
      "OptionName" : "Option 1",
      "VoteCount" : 0.0
    }, {
      "OptionId" : "2",
      "OptionName" : "Option 2",
      "VoteCount" : 0.0
    }, {
      "OptionId" : "3",
      "OptionName" : "Option 3",
      "VoteCount" : 0.0
    }
    }]
}

Answer 1

To update subdocument you can use this:

var update = Update.Set("AnswerList.$.OptionName", "new").Set("AnswerList.$.VoteCount", 5);
collection.Update(Query.And(Query.EQ("_id", new BsonObjectId("50f3c313f216ff18c01d1eb0")), Query.EQ("AnswerList.OptionId", "1")), update);

profiler:

"query" : { "_id" : ObjectId("50f3c313f216ff18c01d1eb0"), "AnswerList.OptionId" : "1" },
"updateobj" : { "$set" : { "AnswerList.$.OptionName" : "new", "AnswerList.$.VoteCount" : 5 } }

And to remove:

var pull = Update<Vote>.Pull(x => x.AnswerList, builder => builder.EQ(q => q.OptionId, "2"));
collection.Update(Query.And(Query.EQ("_id", new BsonObjectId("50f3c313f216ff18c01d1eb0")), Query.EQ("AnswerList.OptionId", "2")), pull);

profiler:

"query" : { "_id" : ObjectId("50f3c313f216ff18c01d1eb0"), "AnswerList.OptionId" : "2" },
"updateobj" : { "$pull" : { "AnswerList" : { "OptionId" : "2" } } }

Another way is to update parent document with modified child collection.