C# 来自FormCollection的asp.net mvc填充视图模型

我有很多类似的ViewModel：

public class RequestForSalaryVM : StatementViewModel
{
  // RequestForSalaryVM properties
}

public class ReliefVM : StatementViewModel
{
  // ReliefVM properties
}

还有很多类似的方法：

[HttpPost]
public ActionResult SaveRelief(User currentUser, ReliefVM statement)
{
    ReliefVM model = (ReliefVM)SaveModel(currentUser, statement);
    if (model == null)
        return RedirectToAction("List");
    return View("Relief", model);
}

[HttpPost]
public ActionResult SaveRequestForSalary(User currentUser, RequestForSalaryVM statement)
{
    RequestForSalaryVM model = (RequestForSalaryVM)SaveModel(currentUser, statement);
    if (model == null)
        return RedirectToAction("List");
    return View("RequestForSalary", model);
}

我想得到这样的东西：

[HttpPost]
public ActionResult SaveStatement(User currentUser, FormCollection statement, string ViewModelName)
{
  Assembly assembly = typeof(SomeKnownType).Assembly;
  Type type = assembly.GetType(ViewModelName);
  object ViewModel = Activator.CreateInstance(type);

  //Fill ViewModel from FormCollection  <= how can I use asp.net mvc binding for this?
  //I do not want to create their own implementation of asp.net mvc binding 
    return View(ViewModelName, ViewModel);
}

public class StatementVMBinder : DefaultModelBinder
{
    // this is the only method you need to override:
    protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
    {
        if (modelType == typeof(StatementViewModel)) // so it will leave the other VM to the default implementation.
        {
            // this gets the value from the form collection, if it was in an input named "ViewModelName":
            var discriminator = bindingContext.ValueProvider.GetValue("ViewModelName");
            Type instantiationType;
            if (discriminator == "SomethingSomething")
                instantiationType = typeof(ReliefVM);
            else // or do a switch case
                instantiationType = typeof(RequestForSalaryVM);

            var obj = Activator.CreateInstance(instantiationType);
            bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(null, instantiationType);
            bindingContext.ModelMetadata.Model = obj;
            return obj;
        }
        return base.CreateModel(controllerContext, bindingContext, modelType);
    }
}

[HttpPost]
public ActionResult SaveStatement（用户currentUser、FormCollection语句、字符串ViewModelName）
{
Assembly Assembly=类型（SomeKnownType）.Assembly；
Type=assembly.GetType（ViewModelName）；
对象ViewModel=Activator.CreateInstance（类型）；
//从FormCollection填充ViewModel如果我是你，我会使用DTO（数据传输对象）包装视图的名称和通过接口访问的ViewModel

[HttpPost]
public ActionResult SaveStatement(User currentUser, VMWrapper wrapper)
{
    IVM model = SaveModel(currentUser, wrapper.Statement);
    if (model == null)
        return RedirectToAction("List");
    return View(wrapper.ViewName, model);
}

但这假设您的视图可以处理VM之间的差异…
您可以尝试或使用以下方法：

但是，我建议您创建自定义ModelBinder，因为它负责创建和填充模型属性

我可以向您展示一个简单的示例，说明如何实现这一点：

基本视图模型

视图模型

模型装订机

然后在
Global.asax
中注册模型绑定器：

ModelBinders.Binders.Add(typeof(StatementViewModel), new StatementModelBinder());

控制器

您是否尝试使用初始化表单集合中的模型值？请查看下面的代码示例

[HttpPost]
public ActionResult SaveStatement(User currentUser, FormCollection statement, string    ViewModelName)
{
  Assembly assembly = typeof(SomeKnownType).Assembly;
  Type type = assembly.GetType(ViewModelName);
  object ViewModel = Activator.CreateInstance(type);

  if (!TryUpdateModel(ViewModel, statement.ToValueProvider()))
  {
     //some another actions
  }

  return View(ViewModelName, ViewModel);
}

您可能可以使用
CustomModelBinder
解决此问题，如下所示：

[HttpPost]
public ActionResult SaveStatement(User currentUser, FormCollection statement, string ViewModelName)
{
  Assembly assembly = typeof(SomeKnownType).Assembly;
  Type type = assembly.GetType(ViewModelName);
  object ViewModel = Activator.CreateInstance(type);

  //Fill ViewModel from FormCollection  <= how can I use asp.net mvc binding for this?
  //I do not want to create their own implementation of asp.net mvc binding 
    return View(ViewModelName, ViewModel);
}

public class StatementVMBinder : DefaultModelBinder
{
    // this is the only method you need to override:
    protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
    {
        if (modelType == typeof(StatementViewModel)) // so it will leave the other VM to the default implementation.
        {
            // this gets the value from the form collection, if it was in an input named "ViewModelName":
            var discriminator = bindingContext.ValueProvider.GetValue("ViewModelName");
            Type instantiationType;
            if (discriminator == "SomethingSomething")
                instantiationType = typeof(ReliefVM);
            else // or do a switch case
                instantiationType = typeof(RequestForSalaryVM);

            var obj = Activator.CreateInstance(instantiationType);
            bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(null, instantiationType);
            bindingContext.ModelMetadata.Model = obj;
            return obj;
        }
        return base.CreateModel(controllerContext, bindingContext, modelType);
    }
}

您的操作需要此签名：

public ActionResult SaveStatement(User currentUser, StatementViewModel viewModel)

但是，您在方法中收到的
viewModel
将是适当的派生类型，因此您应该能够像在单个方法中一样强制转换它

剩下的就是在Global.asax中注册自定义绑定器

[HttpPost]
public ActionResult SaveStatement(User currentUser, FormCollection statement, string    ViewModelName)
{
  Assembly assembly = typeof(SomeKnownType).Assembly;
  Type type = assembly.GetType(ViewModelName);
  object ViewModel = Activator.CreateInstance(type);

  if (!TryUpdateModel(ViewModel, statement.ToValueProvider()))
  {
     //some another actions
  }

  return View(ViewModelName, ViewModel);
}

public class StatementVMBinder : DefaultModelBinder
{
    // this is the only method you need to override:
    protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
    {
        if (modelType == typeof(StatementViewModel)) // so it will leave the other VM to the default implementation.
        {
            // this gets the value from the form collection, if it was in an input named "ViewModelName":
            var discriminator = bindingContext.ValueProvider.GetValue("ViewModelName");
            Type instantiationType;
            if (discriminator == "SomethingSomething")
                instantiationType = typeof(ReliefVM);
            else // or do a switch case
                instantiationType = typeof(RequestForSalaryVM);

            var obj = Activator.CreateInstance(instantiationType);
            bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(null, instantiationType);
            bindingContext.ModelMetadata.Model = obj;
            return obj;
        }
        return base.CreateModel(controllerContext, bindingContext, modelType);
    }
}

public ActionResult SaveStatement(User currentUser, StatementViewModel viewModel)