CODEWITHSUNDEEP
c#mongodbmongodb-querybson
notlkk
notlkk

Reputation: 1231

Query/Find to Return JSON Object in a BsonDocument

I have a document like this:

    { "File" : "xxxxxxx.txt",
      "Content" : [
          {   "tag" : "Book",
              "name" : "TestBook1",
              "value" : "xxx"
          },
          {   "tag" : "Dept",
              "name" : "TestDept1",
              "value" : "yyy"
          },
          {   "tag" : "Employee", 
              "name" : "TestEmployee1",
              "value" : "zzz"
          }]
    }

I can find the document by using:

var filter = Builders<BsonDocument>.Filter.Eq("Content.tag", "Dept");
var result = collection.Find(filter).ToList();

However, this returns the whole document. Is there any way to just get the JSON object ({"tag" : "Dept", "name" : "TestDept1"})?

What I'm trying to get is just the "value" property (in this case, it's "yyy"), instead of the whole document.

UPDATE:

Like Phani suggested, I was able to make this work with the following code:

var subFilter = Builders<BsonDocument>.Filter.Eq("tag", "Dept");
var filter = Builders<BsonDocument>.Filter.ElemMatch("Content", subFilter);
var result =
    collection.Find(filter)
        .Project(Builders<BsonDocument>.Projection.Exclude("_id").Include("Content.$"))
        .ToList();

Upvotes: 0

Views: 2084

Answers (1)

Phani vikranth
Phani vikranth

Reputation: 108

You need to use the ElemMatch projection for this.

Shell query for this : db.testing.find({Content:{$elemMatch:{"tag":"Dept"}}},{"_id":0,"Content.$":1})

C# query will be

Find(x => x.Content.Any(p => p.tag == "Dept")).Project(Builders<BsonDocument>.Projection.Exclude("_id").Include("Content.$")).ToList();

Please check if this is working.

Upvotes: 2

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