是否可以将 LINQ GROUP BY 的结果放入 IEnumerable 列表中

Question

我有以下两个模型

public class DepotDeptMapModel
{
    public string id { get; set; }
    public string title { get; set; }
    public List<DeptModel> subs { get; set; }
}
public class DeptModel
{
        public string id { get; set; }
        public string title { get; set; }
}

我正在使用给定的 LINQ 查询来获取结果

var list = goContext.goDepartmentWorkTime.
            GroupBy(d => new { d.DepotID, d.Depot.DepotName })
        .Select(g => new
        {
            id = g.Key.DepotID,
            title = g.Key.DepotName,
            subs = g.Select(dd => new
            {
                id = dd.DepotID + "." + dd.DepartmentID,
                title = dd.Depot.DepotNo + "." + dd.Department.DepartmentName
            })
        });

是否可以将查询结果放入列表模型中

List<DepotDeptMapModel>  deptList

如有任何帮助，我们将不胜感激

Answer 1

您需要做的就是在 new 调用中使用您的实际类型，而不是匿名类型。但是，由于您想在客户端而不是数据库语句的一部分执行此操作，因此您必须告诉您的上下文在特定点将控制权切换到客户端，这就是 .AsEnumerable() 所做的。

var list = goContext.goDepartmentWorkTime
                    .GroupBy(d => new { d.DepotID, d.Depot.DepotName })
                    .AsEnumerable()
                    .Select(g => new DepotDeptMapModel
                                 {
                                     id = g.Key.DepotID,
                                     title = g.Key.DepotName,
                                     subs = g.Select(dd => new DeptModel
                                                           {
                                                                id = dd.DepotID + "." + dd.DepartmentID,
                                                                title = dd.Depot.DepotNo + "." + dd.Department.DepartmentName
                                                           })
                                 });

Answer 2

Is it possible to get the query result into the list model List<DepotDeptMapModel> deptList?

当然可以，如果您的类是简单的 POCO（= 只有 get/set 属性），这就很容易了。您所要做的就是更改 Select:

.Select(g => new {...

进入：

.Select(g => new DepotDeptMapModel {...

在完整查询下方，稍作优化：Select 在 GroupBy 中使用参数 resultSelect 或：

完成

List<DepotDeptMapModel> deptList = goContext.goDepartmentWorkTime.GroupBy(

    // parameter keySelector: make groups of departments with same key:
    department => new DepotDeptMapModel
    {
        department.DepotID,
        department.Depot.DepotName,
    })

    // parameter ResultSelector, take each key and all departments with this key
    // to make one new DepotDeptMapModel 
    (key, departmentsWithThisKey) => new
    {
        id = key.DepotID,
        title = key.DepotName,
        
        subs = departmentsWithThisKey.Select(department => new DeptModel
        {
            id = department.DepotID + "." + department.DepartmentID,
            title = department.Depot.DepotNo + "." + department.Department.DepartmentName
        })
        .ToList(),
    })
    .ToList();

是否可以将 LINQ GROUP BY 的结果放入 IEnumerable 列表中

Is it possible to get the result from LINQ GROUP BY into the IEnumerable List

linq

ienumerable

asp.net-core