CODEWITHSUNDEEP
c#mongodblinq
Bilgehan
Bilgehan

Reputation: 1227

Mongodb C# query nested document

I use mongodb with c# driver.I have a collection which contains subdocument

public class EntityA 
{
    public string Name { get; set; }

    public string Description { get; set; }

    public List<EntityB> BItems { get; set; }
}

public class EntityB
{
    public string BName { get; set; }

    public string BDesc { get; set; }
}

I want to create query and take list of EntityB items 

from a in mycollection
where BItems.Any(k => k.BName == entity.Name)
select a.BItems;

I can query nested document but when I retrive the list all other child items come to list how can I take list of BItems to meet up my criteria.I can query subdocument but when I want to take list All Bitems are coming to mylist

Upvotes: 3

Views: 4654

Answers (3)

Bilgehan
Bilgehan

Reputation: 1227

AS I Understand SelectMany meets to unwind propert in mongodb and to use unwind property we cannot add criteria directly.

MongoDB finding nested objects that meet criteria

       var result = from k in (from a in col.AsQueryable()
                     from b in a.Columns        
                     select b) where k.ColumnName==a.Name select k;

Upvotes: 1

ocuenca
ocuenca

Reputation: 39326

Well, now I tested with MongoDB C# driver 2.2.3 and MongoDB 3.2.1 and indeed SelectMany is already supported, so you can also do this:

 var entities= mycollection.AsQueryable<EntityA>()
                           .SelectMany(e=>e.BItems, (e,b)=>new {entityA=e,bitem=b})
                           .Where(t => t.entityA.Name == t.bitem.Name)
                           .Select(t=>t.bitem)
                           .ToList();

Update

Another possible solution could be fetching first the data and filtering latter in memory:

var entities= mycollection.AsQueryable<EntityA>()
                          .Select(e=>new{e.Name,e.BItems}).ToList();

var result=entities.SelectMany(e=>e.BItems.Where(b=>b.Name==e.Name));

Upvotes: 0

Nikola.Lukovic
Nikola.Lukovic

Reputation: 1325

If i understood you correctly you want to return BItems collections when BName is equals to it's parents Name field? If that is the case than it goes like this:

var result = from a in mycollection
             from b in a.BItems
             where a.Name == b.BName
             select b;

Upvotes: 2

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