Asp.net core model doesn't bind from form

Question

I catch post request from 3rd-side static page (generated by Adobe Muse) and handle it with MVC action.

<form method="post" enctype="multipart/form-data">
   <input type="text" name="Name">
   ...
</form>

Routing for empty form action:

app.UseMvc(routes => routes.MapRoute(
   name: "default",
   template: "{controller=Home}/{action=Index}"));

But in according action I have model with every property is empty

Action:

[HttpPost]
public void Index(EmailModel email)
{
   Debug.WriteLine("Sending email");
}

Model:

public class EmailModel
{
    public string Name { get; set; }
    public string Email { get; set; }
    public string Company { get; set; }
    public string Phone { get; set; }
    public string Additional { get; set; }
}

Request.Form has all values from form, but model is empty

[0] {[Name, Example]}
[1] {[Email, [email protected]]}
[2] {[Company, Hello]}
[3] {[Phone, Hello]}
[4] {[Additional, Hello]}

Why do you use enctype="multipart/form-data"? You don't need to specify this because your model doesn't contain any file upload. Probably your problem causes from this. Remove and try. — adem caglin
– adem caglin, Commented Oct 21, 2016 at 8:54
@ademcaglin removed enctype attribute. Doesn't help. Still Request.Form has all values, but model is empty. — Kovpaev Alexey
– Kovpaev Alexey, Commented Oct 21, 2016 at 9:01

Stuart · Accepted Answer · 2017-05-02 08:27:36Z

58

Be careful not to give an action parameter a name that is the same as a model property or the binder will attempt to bind to the parameter and fail.

public async Task<IActionResult> Index( EmailModel email ){ ... }

public class EmailModel{ public string Email { get; set; } }

Change the actions parameter 'email' to a different name and it will bind as expected.

public async Task<IActionResult> Index( EmailModel uniqueName ){ ... }

edited May 2, 2017 at 8:27

answered May 2, 2017 at 8:11

Stuart

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6 Comments

Evil Pigeon Over a year ago

Thanks! I had a property named "Model" in my view model which broke the binding.

James Webster Over a year ago

Seems like ASP.NET Core's model binding code could throw us a bone by maybe throwing an exception in this case!

detay Over a year ago

I mean... Wow.. This is something I couldn't find on my own.

hubert17 Over a year ago

You are my angel!

Shukri Adams Over a year ago

Well, that's an hour of pointless debugging I'm never getting back.

|

Velyo · Accepted Answer · 2017-01-10 21:26:59Z

4

I'm not sure it is same case, but I had same problem and nothing really looks to work for me.
The problem in my case was that I had a property called Model in my view model class

public string Model { get; set; }

When I renamed the property to ModelName everything was working fine again, even without FromForm attribute.

Looks like some special property names could be a bit of a problem for asp.net mvc model binding.

So, my advice is to check your model properties and maybe try renaming them one by one in order to check if the problem is there.

Hope this helps.

answered Jan 10, 2017 at 21:26

Velyo

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Comments

HMZ · Accepted Answer · 2020-04-09 03:33:54Z

3

ASP.Net Core 3.1

In my case, I was using a complex model (a model that contains other models, like a shared model) posted by Ajax, so the inputs in the view were automatically named like this "ChildModel.PropertyName" (see code)

   [HttpPost]
   [ValidateAntiForgeryToken] // ("AUVM.PropertyName")
   public async Task<JsonResult> AddUser([FromForm]AUVM aUVM) //Parameter name must match the first part of the input name in order to bind
   {

   }

   [HttpPost]
   [ValidateAntiForgeryToken]
   public async Task<JsonResult> AddUser([FromForm]AUVM someUniqueName) //This is wrong and won't bind
   {

   }

answered Apr 9, 2020 at 3:33

HMZ

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Comments

phen · Accepted Answer · 2016-11-02 15:15:08Z

1

I'm having the same problem this docs helps me to understand Model Binding https://docs.asp.net/en/latest/mvc/models/model-binding.html

I solved my problem by making sure that the property name is exact match in form field name and I also add [FromForm] attribute to specify exactly the binding source.

answered Nov 2, 2016 at 15:15

phen

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Comments

meshtron · Accepted Answer · 2019-03-19 14:25:54Z

1

I ran into this today, and though in hindsight it seems obvious, just thought I'd add that you need to make sure your access modifiers for the Properties on the model you're binding are correct. I had public MyProperty { get; internal set; } on some and they would not bind. Removed internal and they worked just fine.

answered Mar 19, 2019 at 14:25

meshtron

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1 Comment

Steve Silberberg Over a year ago

OMG that's the problem I had. I would have never figured this out without your awesome help. Thank you!!

Justin · Accepted Answer · 2020-01-10 02:05:13Z

I have run in to this issue where the model does not bind when I have more than one constructor on the underlying model like:

public class EmailModel
{
    public EmailModel()
    {}

    public EmailModel(string _name, string _company)
    {
        Name = _name;
        Company = _company;
    }
    public string Name { get; set; }
    public string Email { get; set; }
    public string Company { get; set; }
    public string Phone { get; set; }
    public string Additional { get; set; }
}

Fixed by removing all but one constructor like this:

public class EmailModel
{
    public EmailModel()
    {}

    public string Name { get; set; }
    public string Email { get; set; }
    public string Company { get; set; }
    public string Phone { get; set; }
    public string Additional { get; set; }
}

Emran Hussain · Accepted Answer · 2020-11-06 02:03:20Z

I had the same problem and I want to share what happened in my case and how I got the solution. Perhaps, someone may find it useful to know.

My context was ASP.NET Core 3.1 Razor pages. I had a handler as

public async Task<JsonResult> OnPostLogin([FromForm] LoginInput loginData)
{
  
}

and also I had a property in my ViewModel as

  public LoginInput LoginInput { get; set; }

And in my Razor page, I have used the form like this:

 <form asp-page-handler="Login" method="post">

 <input asp-for="LoginData.UserNameOrEmail">

 .....

So, notice that, in my form, I used the property LoginInput.UserNameOrEmail, but in my handler's parameter, I used the parameter name loginData. How will the ASP.NET Core know that, this LoginInput.UserNameOrEmail is actually loginData.UserNameOrEmail. It can't, right? Therefore, it did not bind my form data.

Then, when I renamed my ViewModel property "LoginInput" to the same name as the handler parameter, like this:

public LoginInput LoginData { get; set; }

The ASP.NET Core then found that the form data was matching the parameter name and then it started to bind properly. My problem was solved.

agenc · Accepted Answer · 2016-10-21 09:03:01Z

0

Change void to ActionResult.

[HttpPost]
public ActionResult Index(EmailModel email)

And don't forget verifying AntiForgeryToken from your view and action.

// to your form in view 
@Html.AntiForgeryToken()
// ------------

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Index(EmailModel email)

answered Oct 21, 2016 at 9:03

agenc

3224 silver badges11 bronze badges

3 Comments

Kovpaev Alexey Over a year ago

Doesn't help. Also I can't use AntiForgeryToken because this page is not mine and generated by 3rd party tools (Adobe Muse)

agenc Over a year ago

I think you can't get it as model with a tool which is not in action view. You can try to get value with form get method, and not as a model. By paramater names. Index(string Name, String Email, String Company, String Phone). And convert this values to your object model in procedure.

Kovpaev Alexey Over a year ago

I also think mvc can't find model or something, and yes I can just use a bunch of action parameters, or fill it with Request.Form in action, or try to do that with IModelBinder, I just want to understand why I can't just use default model binding. Maybe I missed some conventions?

daniel.caspers · Accepted Answer · 2018-09-09 20:56:39Z

0

This issue can also happen if one or more of your properties in the request model fail to bind into an acceptable on the request model.

In my case, I was supposed to pass a List<string> type to a property, but accidentally passed a string. This resulted in the entire request model becoming null

answered Sep 9, 2018 at 20:56

daniel.caspers

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Comments

Community · Accepted Answer · 2020-06-20 09:12:55Z

0

In my case, I was using the MVC 4.0 convention of naming the object you are posting. E.g.,

js: $http.post("SaveAnswer", { answer: answerValues })

C#: public ActionResult SaveAnswer([FromBody] AnswerVM answer) {...}

When I changed the js to $http.post("SaveAnswer", answerValues), everything works.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Apr 22, 2019 at 16:57

Daniel

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