$unset 2D array MongoDB (C#)

user_15400539 0
Viewed 51

Good Morning,

I have a Issue With MongoDb, i'm trying to unset an index of "citations", on my Json you can see 1 field citations with 2 citation : "Saisir ou Selection une citations" and "XD", i'd like to unset XD, how can i achieve this ?

{ 
"_id" : ObjectId("604ca13de0059b65e4e67c01"), 
"username" : "LOL", 
"pass" : "LOL", 
"citations" : [
    [
        {
            "body" : "Saisir ou Selection une citations", 
            "author" : "author", 
            "oeuvre" : "oeuvre", 
            "annee" : NumberInt(1)
        }
    ], 
    [
        {
            "body" : "XD", 
            "author" : "XD", 
            "oeuvre" : "XD", 
            "annee" : NumberInt(3)
        }
    ]
]

}

I've tried Many things :

db.getCollection("Users").update(
{}, {$unset : {"citations.$.body" : "XD"}}
)

and I tried many other variant but i didnt found the right Solution.

PS :

I'm working on a C# Wpf APP, it's would be perfect if you can help me on this langage but otherwise no worries it is not very different

mongodb nosql json c#
2 Answers

In update function you need to give first conditition. Than you may need to use "$pull" for removing values from array.

It should be something like this:

    db.getCollection("Users").update(
      {citations.body: "XD"}, {$pull : {"citations.$.body" : "XD"}}
    )
user_43717670

you will have to use the ElemMatch and PullFilter operators in the c# driver to achieve your goal like so:

var filter = Builders<User>.Filter.ElemMatch(
    u => u.Citations, 
    c => c.Body == "XD");

var update = Builders<User>.Update.PullFilter(
    u => u.Citations,
    c => c.Body == "XD");

await userCollection.UpdateManyAsync(filter, update);

here's another less verbose way to do the same thing using MongoDB.Entities library (which i wrote):

using MongoDB.Entities;
using System.Linq;
using System.Threading.Tasks;

namespace TestApplication
{
    public class User : Entity
    {
        public Citation[] Citations { get; set; }
    }

    public class Citation
    {
        public string Body { get; set; }
    }

    public static class Program
    {
        private static async Task Main()
        {
            await DB.InitAsync("test");

            await new[] {
                new User {
                    Citations = new[]
                    {
                        new Citation { Body = "Saisir ou Selection une citations"},
                        new Citation { Body = "XD"},
                    }
                },
                new User {
                    Citations = new[]
                    {
                        new Citation { Body = "Saisir ou Selection une citations"},
                        new Citation { Body = "XD"},
                    }
                }
            }.SaveAsync();

            await DB.Update<User>()
                    .Match(u => u.Citations.Any(c => c.Body == "XD"))
                    .Modify(f => f.PullFilter(u => u.Citations, c => c.Body == "XD"))
                    .ExecuteAsync();
        }
    }
}

user_43684850
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