C# Find string in List<string> in MongoDB

Question

Have kind of a MongoDB issue here as Im trying to find a collection om matching IDs. As Im building kind of a tree structure based on MongoDB. I have objects that contains multiple attributes like name, parents and children for them to know there relations. Right now I can from and object go though its child ID and load each object one by one. I how ever noticed its much faster got get them as a collection.

So my question is now, how do I find ID of intrest in the collection on tree node objects represented in MongoDB.

example of how the mongoDB document can look

{
  "_id" : ObjectId("523de6c6d7b47f1f74c98ba2"),
  "IDType" : "root",
  "Name" : "test root",
  "Relations" : [{
      "Children" : {
        "ChildrenList" : ["523de725d7b47f1d0c8242f1", "523de746d7b47f1d0c8242f5"]
      },
      "Parents" : {
        "ParentList" : []
      }
    }]
}

So, how would I find one of the IDs by matching by a ID in the ChildrenList ? this as Relations is a array of Children and Parents. and these two contains array of IDs to be matched.

have tried this with out sucess.

IMongoQuery searchQuery = Query.ElemMatch("Children", Query.EQ("ChildrenList", "523de746d7b47f1d0c8242f5"));

The "Children" field is a descendant of "Relations" so minimally you'll need to include that in your query. "Relations.Children" — WiredPrairie
– WiredPrairie, Commented Nov 23, 2013 at 12:36
I also don't understand why the children and parents are stored in an array off of Relations, and then have an extra object level instead of being stored directly. — WiredPrairie
– WiredPrairie, Commented Nov 23, 2013 at 12:39
That's because there should be a possibility to have multiple parent-node-child relations for a single object. Not that I say that is usual, but as I have been in scenarios where this can be in use, I wanted to make this possible in the easiest way. Otherwise you have to fake it, and that can be quiet messy. — Jonas Lindahl
– Jonas Lindahl, Commented Nov 23, 2013 at 13:20

Jonas Lindahl · Accepted Answer · 2013-11-23 15:46:37Z

1

Ok, as I found the solution thanks to WiredPrairie I thought I should post it. The solution was apperantly not using ElemMatch for the parts but writing it like this.

IMongoQuery searchQuery = Query.EQ("Relations.Parents.ParentList", objectID);

Thanks anyways for the help to the right direction.

answered Nov 23, 2013 at 15:46

Jonas Lindahl

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