Question

相关（简化）课程：

    public class Host
    {
        public int HostID { get; set; }
        public String HostName { get; set; }
        public String Description { get; set; }
        public bool Active { get; set; }
    }

    public class Service
    {
        public int ServiceID { get; set; }
        public String Description { get; set; }
        public bool Active { get; set; }

        public int HostID { get; set; }
        public virtual Host Host { get; set; }
    }

我需要在给定主机列表的情况下填充所有服务的列表。因此，对于rsearch.hosts中的每个主机，我需要rsearch.hostservices中的所有服务。

这就是我现在所做的：

rsearch.hostservices = db.Services
.Where(j => rsearch.hosts.Select(c => c.HostID).Contains(j.HostID)).ToList();

但我总是得到以下错误

 System.NotSupportedException: Unable to create a constant value of type 'xxx.Models.Host'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.

Answer 1

var ids = rsearch.hosts.Select(c => c.HostID).ToList();

rsearch.hostservices = db.Services
.Where(j => ids.Contains(j.HostID)).ToList();

Answer 2

rsearch.hostservices = db.Services
.Where(j => rsearch.hosts.Select(c => c.HostID).ToList().Contains(j.HostID))
.ToList();

检查值是否存在于其他列表中

2 个答案: