EntityFramework在具有联接的查询上执行分页 [英] EntityFramework do Paging on a query with a join

问题描述

我有一个带有左联接的查询:

I have a query with a left join in it:

   var query = (from v in context.Vehicles

                //left join vehicleAttributes
                join va in context.VehicleAttributes on v.VehicleId equals va.VehicleId into vAttributes
                from vehicleAttributes in vAttributes.DefaultIfEmpty()

                where v.FleetId == fleetId

                select new { v, vehicleAttributes });

现在我需要对其进行分页.

And now I need to do a paging on it.

这行得通，但可以获取所有行，远远超出了我的实际需求

this works but gets all rows, so much more than i actually need

query.ToList().Select(x => x.v).Distinct().Skip(10 * (page - 1)).Take(10).ToList();

这是我尝试的方法，但是现在我没有联合值

this is what I tried instead but now I don't have the joint values

query.Select(x => x.v).Distinct().ToList().Skip(10 * (page - 1)).Take(10).ToList();

有什么想法吗?

谢谢

推荐答案

ToList()触发对数据库的调用，因此仅在应用跳过并接受"之后才需要执行此操作.您还需要一个OrderBy子句.

The ToList() triggers the call to the database so you need to only do this after you apply the Skip and Take. You'll need an OrderBy clause as well.

您应该可以执行以下操作:

You should be able to do something like this:

var data = (from v in context.Vehicles
         join va in context.VehicleAttributes on v.VehicleId equals va.VehicleId into vAttributes
         from vehicleAttributes in vAttributes.DefaultIfEmpty()
         where v.FleetId == fleetId
         select new { v, vehicleAttributes })
         .OrderBy(p => p.v.FleetId)
         .Skip(10 * (page - 1))
         .Take(10)
         .ToList();

这篇关于EntityFramework在具有联接的查询上执行分页的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！