查询中的Linq计数条件

Question

我陷在这个问题上。 我想获得处于“开发人员”角色的用户，这些用户没有被分配任何任务，或者被分配了3个或更少的被标记为“活动”或“测试”的任务。

我不知道如何声明状态为“活动中，正在测试”的所有任务，并将其汇总为计数声明。

//here i specific role for users
var role = unitOfWork.RoleRepository._context.Roles.SingleOrDefault(m => m.Name == "Developer");

var query = (from u in users
     where u.Roles.Any(r => r.RoleId == role.Id)
     from t in u.ProjectTasks.Where(x => x.Users.Any(user => user.Id == u.Id)).DefaultIfEmpty()
     //here I am able to get those users without assigned tasks but I dont know how to make the second condition with 3 or less tasks
     where ((u.ProjectTasks.Count() == 0) || u.ProjectTasks.Any(z => z.Status == Status.Active || z.Status == Status.Testing))
     select new { User = u } into Users
     group Users by Users.User).ToList(); 

这是我的数据库模型：

Answer 1

可能需要LINQ Count函数：

var query = (from u in users
     where u.Roles.Any(r => r.RoleId == role.Id)
     from t in u.ProjectTasks.Where(x => x.Users.Any(user => user.Id == u.Id)).DefaultIfEmpty()
     where ((u.ProjectTasks.Count() == 0) || u.ProjectTasks.Count(z => z.Status == Status.Active || z.Status == Status.Testing) <= 3)
     select new { User = u } into Users
     group Usersby Users.User).ToList(); 

有关用法示例： http : //www.csharp-examples.net/linq-count/

Answer 2

我使用DataTable模拟了数据库，以显示它是如何完成的

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable AspNetRoles = new DataTable();
            AspNetRoles.Columns.Add("Id", typeof(int));
            AspNetRoles.Columns.Add("Name", typeof(string));

            AspNetRoles.Rows.Add(new object[] { 123, "Developer" });
            AspNetRoles.Rows.Add(new object[] { 456, "Non Developer" });

            DataTable AspNetUserRoles = new DataTable();
            AspNetUserRoles.Columns.Add("UserId", typeof(int));
            AspNetUserRoles.Columns.Add("RoleId", typeof(int));

            AspNetUserRoles.Rows.Add(new object[] { 100, 123 });
            AspNetUserRoles.Rows.Add(new object[] { 200, 456 });
            AspNetUserRoles.Rows.Add(new object[] { 300, 123 });
            AspNetUserRoles.Rows.Add(new object[] { 400, 456 });

            DataTable AspNetUsers = new DataTable();
            AspNetUsers.Columns.Add("Id", typeof(int));

            AspNetUsers.Rows.Add(new object[] { 100 });
            AspNetUsers.Rows.Add(new object[] { 200 });
            AspNetUsers.Rows.Add(new object[] { 300 });
            AspNetUsers.Rows.Add(new object[] { 400 });

            DataTable UserToTask = new DataTable();
            UserToTask.Columns.Add("UserId", typeof(int));
            UserToTask.Columns.Add("TaskId", typeof(int));

            UserToTask.Rows.Add(new object[] { 100, 1000 });
            UserToTask.Rows.Add(new object[] { 100, 1001 });
            UserToTask.Rows.Add(new object[] { 100, 1002 });
            UserToTask.Rows.Add(new object[] { 200, 1001 });
            UserToTask.Rows.Add(new object[] { 200, 1004 });
            UserToTask.Rows.Add(new object[] { 200, 1006 });
            UserToTask.Rows.Add(new object[] { 300, 1005 });
            UserToTask.Rows.Add(new object[] { 300, 1006 });
            UserToTask.Rows.Add(new object[] { 400, 1007 });
            UserToTask.Rows.Add(new object[] { 400, 1008 });

            DataTable ProjectTasks = new DataTable();
            ProjectTasks.Columns.Add("Id", typeof(int));
            ProjectTasks.Columns.Add("Status", typeof(string));

            ProjectTasks.Rows.Add(new object[] { 1000, "Active" });
            ProjectTasks.Rows.Add(new object[] { 1001, "Testing" });
            ProjectTasks.Rows.Add(new object[] { 1002, "Idle" });
            ProjectTasks.Rows.Add(new object[] { 1003, "Active" });
            ProjectTasks.Rows.Add(new object[] { 1004, "Testing" });
            ProjectTasks.Rows.Add(new object[] { 1005, "Idle" });
            ProjectTasks.Rows.Add(new object[] { 1006, "Active" });
            ProjectTasks.Rows.Add(new object[] { 1007, "Testing" });
            ProjectTasks.Rows.Add(new object[] { 1008, "Idle" });

            var results = (from aspNetUser in AspNetUsers.AsEnumerable()
                           join task in UserToTask.AsEnumerable() on aspNetUser.Field<int>("Id") equals task.Field<int>("UserId") 
                           join proj in ProjectTasks.AsEnumerable() on task.Field<int>("TaskId") equals proj.Field<int>("Id")
                           join aspNetUserRole in AspNetUserRoles.AsEnumerable() on aspNetUser.Field<int>("Id") equals aspNetUserRole.Field<int>("UserId")
                           join aspNetRole in AspNetRoles.AsEnumerable() on aspNetUserRole.Field<int>("RoleId") equals aspNetRole.Field<int>("Id")
                           select new { aspNetUser = aspNetUser, task = task, proj = proj, aspNetUserRole = aspNetUserRole, aspNetRole = aspNetRole }).ToList();
            var finalResults = results.GroupBy(x => x.aspNetUser.Field<int>("Id"))
                .Where(x => (x.Select(y => y.task).Count() == 0) || (x.Where(y => (y.proj.Field<string>("Status") == "Active") || (y.proj.Field<string>("Status") == "Testing"))).Count() <= 3).ToList();
        }
    }
}