Remove from subdocument from mongodb version 2.4 by id

问题

This is my document

Post{
  "_id" : 1,
  "Code" : CSUUID("ba22a2a3-e6b5-4ce6-a3ad-20e5196cca46"),
  "Zip" : 123456,
  "Text" : "Hello",
  "Tags" : [{
      "_id" : 1,
      "Tag" : "Tag8"
    }, {
      "_id" : 2,
      "Tag" : "Tag9"
    }, {
      "_id" : 3,
      "Tag" : "Tag10"
    }]
}

I need to delete one of 'Tags' by id in c#. for example: delete from post where tag.id = 2

回答1:

MongoDB.Bson version : 2.0.1.27

MongoDB.Driver version :2.2.0.262

MongoDB.Driver.Code version :2.2.0.262

const int id = 1;
var pull = Builders<Post>.Update.PullFilter(x => x.Tags, a => a.Id == id);
var filter1 = Builders<Post>.Filter.And(Builders<Post>.Filter.Eq(a => a.Id, 1), Builders<Post>.Filter.ElemMatch(q => q.Tags, t => t.Id == id));
collection.UpdateOneAsync(filter1, pull);

回答2:

I found the answer.

var pull = Update<Post>.Pull(x => x.Tags, builder => builder.EQ(q => q.Id, 2)).ToBsonDocument();
var filter1 = Builders<Post>.Filter.And(Builders<Post>.Filter.Eq(a => a.Id, 1),
              Builders<Post>.Filter.ElemMatch(q => q.Tags, t => t.Id == 2));
collection.UpdateOneAsync(filter1, pull);

来源：https://stackoverflow.com/questions/34115181/remove-from-subdocument-from-mongodb-version-2-4-by-id