通过linq进行分组并加入很长时间

Question

Im trying to make a goup by with a multiple join in this method, but it return me nothing

public List<CTarifaAplicada> get_TarifasAplicadas(int id_proforma)
        {
            var pt = (from ta in db.TarifaAplicada
                      where ta.IDProforma == id_proforma
                      join p in db.Proforma on ta.IDProforma equals p.ID
                      join pe in db.PortExpenses on ta.CodigoPE equals pe.CodigoPE
                      join v in db.Voucher on pe.IDVoucher equals v.No
                      select new CTarifaAplicada
                      {
                          CodigoFile = ta.CodigoFile,
                          CodigoPE = ta.CodigoPE,
                          Fecha = ta.Fecha,
                          Id = ta.Id,
                          IDProforma = ta.IDProforma,
                          ITBIS = ta.ITBIS,
                          Monto = ta.Monto,
                          DWT = p.DWT,
                          GRT=p.GRT,
                          LOA=p.LOA,
                          no_Voucher= v.No,
                          voucher=v.Description
                      }).ToList();

            return pt;

Im trying to group by v.No , by doing this.

Json(cta.get_TarifasAplicadas(id_Proforma).OrderBy(n => n.no_Voucher).GroupBy(n => n.no_Voucher)

And this return me nothing. on my grid, Im newbie

Answer 1

Define your method as (returning Enumerable instead of List is more sensible):

public IEnumerable<CTarifaAplicada> get_TarifasAplicadas(int id_proforma)
{
    var pt = (from ta in db.TarifaAplicada
                where ta.IDProforma == id_proforma
                join p in db.Proforma on ta.IDProforma equals p.ID
                join pe in db.PortExpenses on ta.CodigoPE equals pe.CodigoPE
                join v in db.Voucher on pe.IDVoucher equals v.No
                select new CTarifaAplicada
                    {
                        CodigoFile = ta.CodigoFile,
                        CodigoPE = ta.CodigoPE,
                        Fecha = ta.Fecha,
                        Id = ta.Id,
                        IDProforma = ta.IDProforma,
                        ITBIS = ta.ITBIS,
                        Monto = ta.Monto,
                        DWT = p.DWT,
                        GRT=p.GRT,
                        LOA=p.LOA,
                        no_Voucher= v.No,
                        voucher=v.Description
                    });
    return pt;
}

Then group your data and project them as anonymous type as:

var groupedData = cta.get_TarifasAplicadas(id_Proforma)
    .GroupBy(n => new {n.no_Voucher, n.voucher, n.DWT, n.GRT, n.LOA, n.Fecha})
    .Select(g => new
                   {
                       g.Key.no_Voucher,
                       g.Key.voucher,
                       ITBIS = g.Sum(r => r.ITBIS),
                       MONTO = g.Sum(r => r.Monto),
                       g.Key.DWT,
                       g.Key.GRT,
                       g.Key.LOA,
                       g.Key.Fecha 
                   });

Now you can use groupedData to serialize as JSON if your lib allows anonymous type serialization. Otherwise, You must define type according to the projected type and use it.