I have an action with the following annotation,
[HttpGet("update/{hash}")]
public async Task<IActionResult> Update([FromQuery]Model model)
{
// I need to use from model.Hash
return Ok();
}
In addition, I have a simple model like below:
public class Model
{
public string Hash { get; set; }
}
The model binder is not working, because that's clear the hash is not a queryString like ?hash=[value], it's an id.
I can not use another parameter to bind it like:
public async Task<IActionResult> Update(string hash)
because I have a validator for my model.
Is there any way in which I can bind hash to Hash my property?
You can able to bind the route parameter to the model property by using [FromRoute(Name = "hash")] as shown in below.
public class Model
{
[FromRoute(Name = "hash")]
public string Hash { get; set; }
}
Refer this Microsoft doc
Related
I would like to bind an object in a controller through the body of a HTTP Post.
It works like this
public class MyModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
if (bindingContext == null)
throw new ArgumentNullException("No context found");
string modelName = bindingContext.ModelName;
if (String.IsNullOrEmpty(modelName)) {
bindingContext.Result = ModelBindingResult.Failed();
return Task.CompletedTask;
}
string value = bindingContext.ValueProvider.GetValue(modelName).FirstValue;
...
The modelName is viewModel (honestly, I don't know why, but it works...)
My controller looks like this
[HttpPost]
[Route("my/route")]
public IActionResult CalcAc([ModelBinder(BinderType = typeof(MyModelBinder))]IViewModel viewModel)
{
....
i.e. it works, when I make this HTTP-Post request
url/my/route?viewModel=URLparsedJSON
I would like however to pass it through the body of the request, i.e.
public IActionResult Calc([FromBody][ModelBinder(BinderType = typeof(MyModelBinder))]IViewModel viewModel)
In my Modelbinder then, the modelName is "" and the ValueProvider yields null... What am I doing wrong?
UPDATE
Example; Assume you have an interface IGeometry and many implementations of different 2D shapes, like Circle: IGeometry or Rectangle: IGeometry or Polygon: IGeometry. IGeometry itself has the method decimal getArea(). Now, my URL shall calculate the area for any shape that implements IGeometry, that would look like this
[HttpPost]
[Route("geometry/calcArea")]
public IActionResult CalcArea([FromBody]IGeometry geometricObject)
{
return Ok(geometricObject.getArea());
// or for sake of completness
// return Ok(service.getArea(geometricObject));
}
the problem is, you cannot bind to an interface, that yields an error, you need a class! That's where the custom model binder is used. Assume your IGeometryalso has the following property string Type {get; set;}
the in the custom model binding you would simply search for that Type in the passed json and bind it to the correct implementation. Something like
if (bodyContent is Rectangle) // that doesn't work ofc, but you get the point
var boundObject = Newtonsoft.Json.JsonConvert.DeserializeObject<Rectangle>(jsonString);
ASP.Net EF
In ASP.Net EF the custom model binding looks like this
public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext)
here you get the body of the HTTPPost request like this
string json = actionContext.Request.Content.ReadAsStringAsync().Result;
in ASP.Net Core you don't have the actionContext, only the bindingContext where I can't find the body of the HTTP Post.
UPDATE 2
Ok, I found the body, see accepted answer. Now inside the controller method I really have an object from type IGeometry (an interface) that is instantiated inside the custom model binder! My controller method looks like this:
[HttpPost]
[Route("geometry/calcArea")]
public IActionResult CalcArea([FromBody]IGeometry geometricObject)
{
return Ok(service.getArea(geometricObject));
}
And my injected service like this
public decimal getArea(IGeometry viewModel)
{
return viewModel.calcArea();
}
IGeometry on the other hand looks like this
public interface IGeometry
{
string Type { get; set; } // I use this to correctly bind to each implementation
decimal calcArea();
...
Each class then simply calculates the area accordingly, so
public class Rectangle : IGeometry
{
public string Type {get; set; }
public decimal b0 { get; set; }
public decimal h0 { get; set; }
public decimal calcArea()
{
return b0 * h0;
}
or
public class Circle : IGeometry
{
public string Type {get; set; }
public decimal radius { get; set; }
public decimal calcArea()
{
return radius*radius*Math.Pi;
}
I found a solution. The body of a HTTP Post request using ASP.NET Core can be obtained in a custom model binder using this lines of code
string json;
using (var reader = new StreamReader(bindingContext.ActionContext.HttpContext.Request.Body, Encoding.UTF8))
json = reader.ReadToEnd();
I found the solution after looking at older EF projects. There the body is inside the ActionContext which is passed separately as an argument in the BindModel method. I found that the same ActionContext is part of the ModelBindingContext in ASP.Net Core, where you get an IO.Stream instead of a string (easy to convert :-))
I just start do work on MVC4 Asp.Net
I have this class in my models
namespace PhoneBook.Models
{
public class User
{
public string Username { get; set; }
public string Password { get; set; }
public static String writeasd(){
return "asd";}
}
I have this method in my controller:
public ActionResult Main()
{
ViewBag.Username = Request.Form["username"];
ViewBag.Password = Request.Form["password"];
var user = new User()
return View(user);
}
However when I tried to call this method from my view like this:
#User.writeasd()
It gives error. What is the problem? Can you help me?
Note : I have #using PhoneBook.Models in the beginning of my view
When using a strongly typed view as you are there, you need two things.
One is a model directive
#model PhoneBook.Models.User
Then you can reference your model using the Model property of the view page.
So in your instance, you would use
#Model.writeasd()
HTH
I want to assign my url parameters to Model properties, passed as a parameter to the associated Action. For example;
Say, my url is http://www.example.com/Item/Index?color=red&size=50
My action inside the controller is like below:
public class ItemController : Controller
{
public ActionResult Index(MyModel myModel)
{
//
return View(myModel);
}
}
I want to configure the model or whatever necessary so that my model takes the color and size as field values. The following didn't work:
public class MyModel
{
[Display(Name = "color")]
public string Color{ get; set; }
[Display(Name = "size")]
public string Size{ get; set; }
}
What would be the correct way to solve the problem?
Thanks for any suggestion.
Update
Well, yes! The code above would work correctly, because Url parameter names are the same as model property names. I should explain my problem exactly as I encounter for the next time, sorry.
I must correct a part of my question to make it clear. The url should have been: http://www.example.com/Item/Index?c=red&s=50 to detect the problem.
If the url is like that, the code would not work. Because Url parameters don't have the same name as Model properties.
Updated model is below:
public class MyModel
{
[Display(Name = "c")]
public string Color{ get; set; }
[Display(Name = "s")]
public string Size{ get; set; }
}
Try adding [FromUri] in front of the parameter.
public class ItemController : Controller
{
public ActionResult Index([FromUri] MyModel myModel)
{
// do something
return View();
}
}
debugging the issue
Here are some suggestions in debugging the issue, as it should work out of the box.
try binding to primitive types
public class ItemController : Controller
{
public ActionResult Index(string color, string size)
{
// do something
return View();
}
}
Try reading out of the request object directly
var size = this.Request["size"];
If either of those work there is an issue with your model binding.
Update
If you want to have the query string parameters different to the model in MVC you'll need to have a custom model binder. Take a look at Asp.Net MVC 2 - Bind a model's property to a different named value and http://ole.michelsen.dk/blog/bind-a-model-property-to-a-different-named-query-string-field.html which extends the answer a little.
https://github.com/yusufuzun/so-view-model-bind-20869735 has an example with some html helpers that could be useful.
ASP.NET MVC (or rather Html.Helpers and base page implementation) assumes that there will be one type for both rendering and posting (namely Model).
This is a violation of ISP, isn't it?
I am tempted to derive my Edit views (those that have different render-data, and post-data) from a custom EditPageBaseView<TViewModel, TFormData>.
The problem is I want my validation and post work against FormData instance (stored inside ViewModel), but MVC assumes that entire ViewModel will be POSTed back.
Is there an OOB way to facilitate that? (I didn't find one if there is).
Is it a bad idea (in concept) to have separate data types for different operations exposed by a service (a view in this case).
I tend to follow the CQRS model when constructing my view models. All rendering is done with ViewModel classes and all posting back is done with Command classes. Here's a contrived example. Let's say we have a View with a small form for creating users.
The ViewModel and Command classes looks like this:
public abstract class ViewModel {}
public abstract class Command: ViewModel
public class CreateUserViewModel : ViewModel
{
public string Username { get; set; }
public string Password { get; set; }
public string PasswordConfirm { get; set; }
}
public class CreateUserCommand : Command
{
public string Username { get; set; }
public string Password { get; set; }
public string PasswordConfirm { get; set; }
}
The UserController creates a CreateUserViewModel as the model for the Get request and expects a CreateUserCommand for the Post request:
public ActionResult CreateUser()
{
// this should be created by a factory of some sort that is injected in
var model = new CreateUserViewModel();
return View(model);
}
[HttpPost]
public ActionResult CreateUser(CreateUserCommand command)
{
// validate and then save the user, create new CreateUserViewModel and re-display the view if validation fails
}
Model binding takes care of ensuring that the properties of the Posted CreateUserCommand are populated properly, even though the Get View is bound to a CreateUserViewModel.
They don't have to match, but they do match by default.
If you don't want them to match, you can specify a different model in your Form or ActionLink:
Example of a Mismatch using Razor and C#:
Index.chtml:
#model FirstModel
<div>
#using (Html.BeginForm("Action", "ControllerName", new { ParameterName = new SecondModel { First = "First", Second = "Second" } }, FormMethod.Post)) {
<input type="submit" value="Submit Button" />
}
</div>
The Controller:
public class ControllerName : Controller {
public ActionResult Index() {
return View(new FirstModel());
}
public ActionResult Action(SecondModel ParameterName) {
return View() // Where to now?
}
This is probably quite straight forward for some, however I'm a bit confused and can't find a decent example. Say I'm using view models and my POST action takes in that view model. Typically I would do something along the following lines:
[HttpPost]
public ActionResult Update(UserViewModel uvm)
{
User user = Mapper.Map<UserViewModel, User>(uvm);
_repository.Update(user);
return RedirectToAction("Index");
}
Although this isn't the full picture. The mapping would work fine, however if I were to just update what I've mapped then it'd get rid of valuable data in the database because of course in this case I'm not updating the password or other details.
My repository looks something like this:
public void Update(User user)
{
User u = Session.QueryOver<User>().Where(x => x.UserName == user.UserName).SingleOrDefault();
if (u == null)
throw new Exception("User not found");
u.Forename = user.Forename;
u.Surname = user.Surname;
u.EmailAddress = user.EmailAddress;
}
[I'm using NHibernate so it'll save the object back to the DB once the session is closed (after the request has finished) automatically for me.]
So my question is, in my repository should I load the "User" entity, then update the values I want, and then save it back, or is there another method to do this? The reason I ask is because it seems a bit... "manual" if you see what I mean? Perhaps it is correct, but I just wanted to see opinions of those with more experience in this area.
Cheers
I use the following approach:
[HttpPost]
public ActionResult Update(UserViewModel uvm)
{
User user = _userRepository.FindById(uvm.Id);
user.Forename = uvm.Forename;
user.Surname = uvm.Surname;
user.EmailAddress = uvm.EmailAddress;
_userRepository.Update(user);
return RedirectToAction("Index");
}
UPDATE:
To address the comments about AutoMapper here's how to proceed:
Let's take for example the following classes:
public class UserViewModel
{
public string Forename { get; set; }
public string Surname { get; set; }
public string EmailAddress { get; set; }
}
public class User
{
public string Forename { get; set; }
public string Surname { get; set; }
public string EmailAddress { get; set; }
public string Password { get; set; }
}
We don't want to modify the user password in the UI. So we express our intention to AutoMapper:
Mapper
.CreateMap<UserViewModel, User>()
.ForMember(dest => dest.Password, opt => opt.Ignore());
and then:
[HttpPost]
public ActionResult Update(UserViewModel uvm)
{
// Fetch the original model we would like to update
User user = _userRepository.FindById(uvm.Id);
Mapper.Map(uvm, user);
// At this stage the user model will have its
// Forename, Surname and EmailAddress properties
// updated from the view model and its Password property
// will remain the one we got from the repository
_userRepository.Update(user);
return RedirectToAction("Index");
}
UPDATE 2:
To address the question in the comments about configuring AutoMapper I usually use Profiles:
public class UsersProfile : Profile
{
protected override void Configure()
{
Mapper
.CreateMap<UserViewModel, User>()
.ForMember(dest => dest.Password, opt => opt.Ignore());
Mapper
.CreateMap<User, UserViewModel>();
}
}
and then have a registry class which registers all the mappers:
public class MappingsRegistry
{
public static void Configure()
{
Mapper.AddProfile(new UsersProfile());
Mapper.AddProfile(new SomeOtherProfile());
...
}
}
which is called in Application_Start:
MappingsRegistry.Configure();
Finally my controllers have a reference to the mapping engine:
public class UsersController : Controller
{
private readonly IUsersRepository _repository;
private readonly IMappingEngine _mappingEngine;
public ContratsFCController(IUsersRepository repository, IMappingEngine mapperEngine)
{
_repository = repository;
_mapperEngine = mapperEngine;
}
[AutoMap(typeof(User), typeof(UserViewModel))]
public ActionResult Update(int id)
{
var user = _repository.FindById(id);
return View(user);
}
[HttpPost]
public ActionResult Update(UserViewModel uvm)
{
if (!ModelState.IsValid)
{
return View(uvm);
}
var user = _repository.FindById(uvm.Id);
_mapperEngine.Map(uvm, user);
_repository.Update(user);
return RedirectToAction("Index");
}
}
Now all that's left is to instruct your DI framework to pass the Mapper.Engine property to the constructor and in your unit tests obviously substitute them with an appropriate mock.