基於屬性值創建動態Linq查詢

Question

我有一個包含許多bool類型屬性的類。

public class FilterModel 
{
    public bool Hotel { get; set; }
    public bool Apartment { get; set; }
    public bool Guesthouse { get; set; }

}

我正在根據這些屬性是true還是false動態構建LINQ查詢。 例如，如果我有這個類的實例並且Hotel設置為true。 我想生成類似的LINQ查詢

var q = from accom in db.Accommodation
                     where accom.Hotel == true 
                     select accom;

提前致謝

Answer 1

你在找這樣的東西嗎？

IQueryable<Accommodation> query = db.Accommodation;

if (filterModel.Hotel)      query = query.Where(a => a.Hotel);
if (filterModel.Apartment)  query = query.Where(a => a.Apartment);
if (filterModel.Guesthouse) query = query.Where(a => a.Guesthouse);

return query;

Answer 2

你想要這樣的東西：

var filterModel = GetFilterModelFromSomewhere();
var q = db.Accomodation;

if (filterModel.Hotel)
    q = q.Where(accom => accom.Hotel);

if (filterModel.Apartment)
    q = q.Where(accom => accom.Apartment);

if (filterModel.Guesthouse)
    q = q.Where(accom => accom.Guesthouse);

由於查詢在您枚舉之前不會執行（通過ToList（）或等效函數），您可以根據動態條件在​​代碼中逐個構建它。