问题描述
控制器调用 IValidatableObject.Validate 内部并传递 ValidationContext 对象作为参数。我想用 validationContext.GetService（）方法来获得一个服务对象，并使用它。
Controller calls IValidatableObject.Validate internally and passes a ValidationContext object as an argument. I want to use validationContext.GetService() method to get a service object and use it.
我可以通过这个服务作为一个依赖使用AutoFac（DI注入DLL）中的控制器构造。我如何使它availale到 ValidationContext 对象？
I can pass this service as a dependency to controller constructor using AutoFac(DI Injection dll). How do i make it availale to the ValidationContext object?
这个计算器的问题可能包含答案，但我不完全理解：Asp.Net MVC3：在ValidationContext设置自定义的IServiceProvider这样验证可以解决服务
This stackoverflow question might contain the answer but i do not understand it fully : Asp.Net MVC3: Set custom IServiceProvider in ValidationContext so validators can resolve services
下面是code：
型号：员工
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
namespace ValidationContextDemo.Models
{
public class Employee : IValidatableObject
{
public int Id { get; set; }
public string Name { get; set; }
public int DepartmentId { get; set; }
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
var result = new List<ValidationResult>();
var EmployeeService = (Service.EmployeeService)validationContext.GetService(typeof(Service.EmployeeService));
if (!EmployeeService.IsValidDepartment(this.DepartmentId))
{
result.Add(new ValidationResult("This DepartmentId does not exists"));
}
return result;
}
}
}
存储库：EmployeeRepository
Repository : EmployeeRepository
using System.Collections.Generic;
using System.Linq;
namespace ValidationContextDemo.Models
{
public class EmployeeRepository
{
public EmployeeRepository()
{
Employees = new List<Employee>() {
new Employee{Id=1, Name="Alpha", DepartmentId=1},
new Employee{Id=2, Name="Beta", DepartmentId=1},
new Employee{Id=3, Name="Gamma", DepartmentId=1}
};
}
public List<Employee> Employees { get; set; }
public void AddEmployee(Employee e)
{
Employees.Add(e);
}
public void UpdateEmployee(int id, Employee e)
{
Employee emp = Employees.Where(x => x.Id == id).FirstOrDefault();
emp.Name = e.Name;
emp.DepartmentId = e.DepartmentId;
}
public void DeleteEmployee(Employee e)
{
Employees.Remove(e);
}
}
}
验证来源：枚举
namespace ValidationContextDemo.Enums
{
public enum Department
{
Engineering=1,
Sales=2,
Shipping=3,
HumanResources=4
}
}
服务：的EmployeeService
Service : EmployeeService
using System;
using System.Linq;
namespace ValidationContextDemo.Service
{
public class EmployeeService
{
public bool IsValidDepartment(int departmentId)
{
return Enum.GetValues(typeof(Enums.Department)).Cast<Enums.Department>().Contains((Enums.Department)departmentId);
}
}
}
的IServiceProvider：EmployeeServiceProvider
IServiceProvider : EmployeeServiceProvider
using System;
namespace ValidationContextDemo.Service
{
public class EmployeeServiceProvider: IServiceProvider
{
public object GetService(Type serviceType)
{
if (serviceType==typeof(EmployeeService))
{
return new EmployeeService();
}
return null;
}
}
}
控制器：EmployeeController
Controller : EmployeeController
using System.ComponentModel.DataAnnotations;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using ValidationContextDemo.Models;
using ValidationContextDemo.Service;
namespace ValidationContextDemo.Controllers
{
public class EmployeeController : ApiController
{
EmployeeRepository _repository;
EmployeeServiceProvider _serviceProvider;
public EmployeeController()
{
_repository = new EmployeeRepository();
_serviceProvider = new EmployeeServiceProvider();
}
public IHttpActionResult Get()
{
return Json(_repository.Employees);
}
public HttpResponseMessage Post(Employee e)
{
ValidationContext vContext = new ValidationContext(e, _serviceProvider, null);
e.Validate(vContext);
_repository.AddEmployee(e);
return new HttpResponseMessage(HttpStatusCode.Created);
}
}
}
通知员工模型验证方法的ValidationContext参数。模型之前绑定，当验证发生，ValidationContext的IServiceProvider的部分为null。
Notice the ValidationContext parameter in Validate method of Employee model. Before model binding, when the validation happens, the IServiceProvider part of ValidationContext is null.
所以，模型绑定后，当code里面我的控制器动作邮报的达到，我创建另一个ValidationContext有_serviceProvider并再次调用验证。
So, after model binding, when the code reaches inside my Controller Action "Post", i create another ValidationContext with a _serviceProvider and call Validate again.
我的问题是，我怎么能模型绑定之前有这个_serviceProvider我ValidationContext。
My question is , how can i have this _serviceProvider in my ValidationContext before model binding.
请让我知道，如果这还不清楚。
Please let me know if this is still not clear.
请注意：我创建了这个例子这一问题的缘故，我没有使用Autofac在这个例子中DI容器
Note: I created this example for the sake of this question, i am not using Autofac as a DI container in this example.
推荐答案
首先你上面code例子是pretty无关，你所面临的，因为你可能会解决此问题黑客通过简单的空问题检查员工的模型，你明确地验证它：
For starters your above code example is pretty irrelevant to the problem you are facing because you can potentially hack around the issue by a simple null check in the Employee model as you are validating it explicitly:
ValidationContext vContext = new ValidationContext(e, _serviceProvider, null);
e.Validate(vContext);
我假设（理想情况下）你不想这样做，明确和遗憾的是没有简单的方法。你必须建立一个公平的量的管道（即模型粘合剂等）的挂钩到MVC /管道的WebAPI。 这个解决方案会为你最有可能的工作，如果你必须遵循它的时候。）
I assume (ideally) you don't want to do that explicitly and unfortunately there is no easy way. You have to set up a fair amount of plumbing (i.e. model binders etc) to hook into the MVC/WebApi pipelines. This solution will most likely work for you if you have the time to follow it :).
PS：该解决方案迎合对MVC，但我看不出有任何理由可以调整为API
PS: The solution is catered towards MVC but I don't see any reason why it can be tweaked for the API.
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