Question

I have a table similar to below:

Data {
    id varchar(50),
    pId uniqueidentifier ,
    fId uniqueidentifier ,
    xid uniqueidentifier,
    flag smallint 
}

The table contains a lot of duplicate rows since pId and fId is a 1:n relationship and fId to xId is a 1:n relationship too.

I want to query this table and populate a obj as below:

class P
{
    Guid id;
    List<F> fList; 
}

class F
{
    Guid id;
    List<X> xList; 
}


class X
{
    Guid id;
    byte flag; 
}

I am learning Linq. Any solutions using Linq to populate class P from the table would be helpful.

Thanks!

Answer 1

This query will return IEnumerable<P> (not sure about converting smallint to boolean but other stuff should work)

var query = from p in context.Data
            group p by p.pId into gp
            select new P()
            {
                id = gp.Key,
                fList = (from f in gp
                         group f by f.fId into gf
                         select new F()
                         {
                             id = gf.Key,
                             xList = gf.Select(x => new X() { id = x.xid, 
                                                              flag = x.flag })
                                       .ToList()
                         }).ToList()
            };

Comments:

gp will contain all rows corresponding to some pId, in other words – it returns all fId, which related to pId.

gf will contain all rows from previous result which relate to some fId (i.e. all xids related to fId)