My class:
class Product
{
public string _id {get; set;}
public IEnumerable<Item> Items {get; set;}
public int ItemsCount {get; set;}
}
class Item
{
public string Name {get; set;}
}
I need to select Items only and process skip limit (paging) for them. Count I can store in the object. Is it possible to use mongo for that or should I put Items to another collection?
we can have two scenarios here:
We are always requesting ONE main document and need to have skip/limit on this particular array.
We are requesting an unknown number of documents and then we could do skip/limit on a kind of merged array from all source ones.
Both solutions are using aggregation framework with $unwind stage, the diffrence is that $match in first case always returns only one document (let's say matched by objectId).
var aggregate = collection.Aggregate().Match(x => x.Id == ourNeededId)
.Unwind("Items").Skip(3).Limit(3).Project<Product>(project);
As output we will get 3 documents which we can a) merge using $group server side or iterate and process in c# code.
EDIT
var aggregate =
collection.Aggregate()
.Match(x => x._id == "some id here")
.Unwind("Items")
.Skip(3)
.Limit(3)
.Group(BsonDocument.Parse("{_id:{id:'$_id', ItemsCount:'$ItemsCount' },Items:{$push:'$Items'} }"))
.Project<Product>(BsonDocument.Parse("{_id:'$_id.id', ItemsCount:'$_id.ItemsCount', Items:1 }"))
.ToList();
Any comments welcome!
