Merge two collections in mongodb using c#

Question

I have two collections in mongodb.I am retreiving data from two collections independently working gud.But when I am implementing paging using skip and take methods I am getting data from both the collections like this

paging = new Pagination() { CurrentPage = pageNumber, ItemsPerPage = 16 };
var results = dataTable.FindAs<TradeInfo(queryAll).Skip(paging.Skip).Take(paging.Take).ToList<TradeInfo>();
paging.TotalCount = Convert.ToInt32(dataTable.Find(query).Count());
var results2 = new List<TradeInfo>();
if (dataTable2 != null)
{
    results2 = dataTable2.FindAs<TradeInfo(queryAll).Skip(paging.Skip).Take(paging.Take).ToList<TradeInfo>();
    int count = Convert.ToInt32(dataTable2.Find(query).Count());
    paging.TotalCount = paging.TotalCount + count;
    results.AddRange(results2);
 }

I am giving results as Itemssource to Datagrid and I am getting total 32 items per page. How can I do that is there any joins concept in Mongodb.Two collections columns are same. How can I do it? Please help me in doing that....

Thanks, jan

Does the answers to this question: http://stackoverflow.com/questions/2350495/how-do-i-perform-the-sql-join-equivalent-in-mongodb help? — Christian Horsdal, Jan 18 '12 at 07:54
No in two collections i have same column names but not the same data its some thing like concatenating the two strings as concatenating two collections — jan, Jan 18 '12 at 09:14

score 0 · Answer 1 · answered Feb 03 '12 at 15:01

I believe what you are looking for here is more of a Union than a Join.

Unfortunately there is no such concept in MongoDB. If your paging is dependent on a query, which in this case it seems it might be, your only real option is to create and maintain a single merged collection which gets updated every time a document is added or saved to either of these two collections. Then you can skip and take on the single collection after applying the query to it.

Merge two collections in mongodb using c#

1 Answers1