c# - Linq query with grouping to fetch youngest date -

my case, see below image:

i designed query , added grouping grouping not reduce records youngest contractenddate. appears have no effect on result.

public iqueryable<soonobsoletecontractsviewmodel> get()     {  var countries = unitofwork.getall<country>(); var companies = unitofwork.getall<company>(); var contracts = unitofwork.getall<contract>();  var query = country in countries             join company in companies on country.id equals company.countryid             join contract in contracts on company.id equals contract.companyid              select new soonobsoletecontractsviewmodel             {                 countryname = contry.name,                 companyname = company.name,                 companyid = company.companyid                 contractbegindate = contract.begin,                 contractenddate = contract.end,                 contractid = contract.id             };              query.groupby(c => c.companyid, (key, e) => e.orderby(f => f.contractenddate).first());         return query;     } 

any appreciated.

group country , company record in group recent contract end date.

var result = query              .groupby(_ => new { _.countryname, _.companyid})              .select(g => g.orderbydescending(c => c.contractenddate).first())              .tolist(); 

or put way

var query = contry in countries             join company in companies on country.id equals company.countryid             join contract in contracts on company.id equals contract.companyid             let viewmodel = new soonobsoletecontractsviewmodel             {                 countryname = contry.name,                 companyname = company.name,                 companyid = company.companyid                 contractbegindate = contract.begin,                 contractenddate = contract.end,                 contractid = contract.id             }             group viewmodel new { viewmodel.countryname, viewmodel.companyid } g             select g.orderbydescending(c => c.contractenddate).first(); 

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