列出来自2个不同表/模型的数据

Posted 2021-03-26

我试图在视图页面中显示列表，从2个不同的表/模型中获取数据。

（表1）Table_Service：

1. ID
2. name

（表2）Table_Request：

1. SERVICE_ID
2. 描述
3. 请求者
4. 状态

表1和表2是Id / Service_Id的链接。

我的视图页面应该是（表2）Table_Request列表：

1. SERVICE_ID
2. 名称（来自表1）
3. 描述
4. 请求者
5. 状态

我的观看页面如下：

@model IEnumerable<OnlinePlatform.Models.ServiceRequests>
<section class="section">
<div class="row">
    <div class="col-md-12">
        <h2>Please choose a service to start</h2>
        <br />
        <div class="row">
            <div class="container">
                <table class="table">
                    <thead>
                        <tr>
                            <th>Id</th>
                            <th>Name</th>
                            <th>Description</th>
                            <th>Start Date</th>
                            <th>System Owner</th>
                            <th>Created By</th>
                            <th></th>
                        </tr>
                    </thead>

                    @foreach (var item in Model)
                    {
                        <tbody>
                            <tr>
                                <td>@item.Id</td>

                                <td>@item.Id</td>
                                <td>@item.ServiceId</td>

                                <td>@item.Name</td>

                                <td>@item.RequestorId</td>
                                <td>@item.Description</td>
                                <td>@item.Status</td>

                                <td><button type="button" class="btn">Edit</button></td>
                            </tr>
                        </tbody>
                    }
                </table>
            </div>
        </div>
    </div>
</div>

我的控制器如下：

public ActionResult Service_Request()
    {
        var dao = new ServicesDAO();
        return PartialView("Service_Request", dao.ServiceRequestGetAll().ToList());
    }

public IQueryable<ServiceRequests> ServiceRequestGetAll()
    {
        var result = DB.ServiceRequests.OrderBy(r => r.Id);
        return result;
    }

如何显示从（Table1）Table_Service获取的名称？

答案

由于您希望将混合结果集作为IQueryable<T>返回，因此应使用Join()查询并将查询结果放入viewmodel中：

1）Lambda版本

public IEnumerable<ServiceRequestsVM> ServiceRequestGetAll()
{
    var result = DB.ServiceRequests.Join(DB.Services,
                                         x => x.Service_Id, // Source table foreign key
                                         y => y.Id, // Joined table primary key
                                         (x, y) => new ServiceRequestsVM { Id = x.Id, Service_Id = x.Service_Id, Name = y.Name, Description = x.Description, Requestor = x.Requestor, Status = x.Status })
                                        .OrderBy(z => z.Service_Id).ToList();

    return result;
}

2）查询表达式版本

public IEnumerable<ServiceRequestsVM> ServiceRequestGetAll()
{
    var result = (from srv in DB.Services
                 join srq in DB.ServiceRequests
                 on srv.Id equals srq.Service_Id
                 select new ServiceRequestsVM
                 {
                     Id = srq.Id,
                     Service_Id = srq.Service_Id,
                     Name = srv.Name,
                     Description = srq.Description,
                     Requestor = srq.Requestor,
                     Status = srq.Status
                 }).OrderBy(z => z.Service_Id).ToList();
    return result;
}

Viewmodel示例

public class ServiceRequestsVM
{
    public int Id { get; set; }
    public int Service_Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string Requestor { get; set; }
    public string Status { get; set; }
}

然后更改@model指令以使用具有两个表的组合属性的viewmodel：

@model IEnumerable<OnlinePlatform.Models.ServiceRequestsVM>

控制器应如下所示：

public ActionResult Service_Request()
{
    var dao = new ServicesDAO();
    return PartialView("Service_Request", dao.ServiceRequestGetAll());
}

完成这些步骤后，模型绑定应该完全起作用。

另一答案

通过使用ID连接两个表来获取记录。

仅供参考，

var result= from req in DB.Table_Request
            join service in DB.Table_Service
            on req.Service_id equals  service.id
           select new ServiceRequests
           {
             Name=service.Name,
             ServiceID=req.Service_Id,

             // Followed model Properties 
            }.ToList();

另一答案

我建议你创建这样的服务：

IServiceManager.cs：

public interface IServiceManager
{
    IEnumerable<ServiceRequests> GetAllServiceRequests();

    Service GetService(string serviceId);
}

ServiceManager.cs：

public class ServiceManager : IServiceManager
{
    public ApplicationDbContext _dbContext { get; set; }

    public ServiceRequest(ApplicationDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    public IEnumerable<ServiceRequests> GetAllServiceRequests()
        => _dbContext.ServiceRequests.OrderBy(r => r.Id);

    public Service GetService(string serviceId)
        => !string.IsNullOrEmpty(serviceId) 
               ? _dbContext.Services.SingleOrDefault(x => x.Id == serviceId) : null;
}

Startup.cs：

services.AddTransient<IServiceManager, ServiceManager>();

控制器：

public ActionResult Service_Request()
{
    return View();
}

Service_Request.cshtml：

@model IEnumerable<OnlinePlatform.Models.ServiceRequests>
@inject IServiceManager serviceManager

@foreach (var request in serviceManager.GetAllServiceRequests())
{
    var service = serviceManager.GetService(request.Service_Id);

    <!-- you can use @service.Name here... -->
}