動態LINQ2Entities查詢無法將IEnumerable轉換為bool

Question

這里的建立行和組織行會產生以下錯誤：它們無法將IEnumerable隱式轉換為bool。 我想念什么？ 在方法結束之前，我不能使用貪婪運算符。 我敢肯定這很簡單，但我看不到。

IQueryable<User> query = context.Users;

if (usvm.EstablishmentId > 0)
    query = query.Where(x => x.UserEstablishments
        .Where(y => y.UserEstablishmentId == usvm.EstablishmentId));

if (usvm.OrganisationId > 0)
    query = query.Where(x => x.UserEstablishments
        .Where(y => y.Establishment.OrganisationId == usvm.OrganisationId));

if (!String.IsNullOrEmpty(usvm.Forename))
    query = query.Where(x => x.Forename == usvm.Forename);

if (!String.IsNullOrEmpty(usvm.Surname))
    query = query.Where(x => x.Surname == usvm.Surname);

if (usvm.DOB != null)
    query = query.Where(x => x.DOB == usvm.DOB);

List<User> m = query.ToList();
return ToViewModel(m);

Answer 1

您可以使用任何方法：

if (usvm.EstablishmentId > 0)
    query = query.Where(x => x.UserEstablishments
        .Any(y => y.UserEstablishmentId == usvm.EstablishmentId));

if (usvm.OrganisationId > 0)
    query = query.Where(x => x.UserEstablishments
        .Any(y => y.Establishment.OrganisationId == usvm.OrganisationId));