如何使用实体框架为特定实体显式加载特定的相关实体?

我为存储库模式的实现做了类似的事情。关键是调用 Load 最后。

我们有

public virtual void Load<TOut>(T entity, Expression<Func<T, ICollection<TOut>>> loadExpression, Expression<Func<TOut, bool>> filter) where TOut : class
{
    Context.Entry(entity).Collection(loadExpression).Query().Where(filter).Load();
}

所以你可以试试看

dbContext.Entry(location).Collection(b => b.Staffs).Query()
    .Where(s => s.Roles.Any(r => r.Name=="Supervisor")).Load();

Linq2Entities 查询您的案例。

var locationWithStaff = (from location in dbContext.Locations
                         select new
                         {
                             location,
                             Staffs = (from staff in location.Staffs
                                       where staff.Roles.Any(r => r.Name=="Supervisor")
                                       select staff).ToList()
                          }).ToList();

dbContext.Locations.SelectMany(b => b.Staffs).Where(s => s.Roles.Any(r => r.Name=="Supervisor"));

您可以在SelectMany中返回一个匿名类型,该类型将包含位置属性,例如:

dbContext.Locations.SelectMany(x => x.Staffs, (x, Staffs) => 
                   new { locationID = x.LocationID, SomeOtherProperty = x.OtherProperty , Staff = Staffs })
                  .Where(y => y.Staff.Roles.Any(z => z.Name == "Supervisor"));