Sonrobby Sonrobby - 21 days ago 10
C# Question

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

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

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.