Bind properties FromForm .NET Core Web API

Question

I have .NET Core Web API project. One of my action controller is:

[HttpPost]
public async Task<IActionResult> Notify([FromForm] NotifyInput input)
{ ... }

NotifyInput.cs file is in separate project (.NET Standard):

public string BodyPlain { get; set; }

public string BodyHtml { get; set; }

public List<Attachment> Attachments { get; set; }

public class Attachment
{
    public int Size { get; set; }

    public string Url { get; set; }

    public string Name { get; set; }

    public string ContentType { get; set; }
}

And params I send to this method are:

body-plain: 123
body-html: <p>123</p>
attachments: [{"url": "http://example.com", "content-type": "image/jpeg", "name": "pexels-photo.jpg", "size": 62169}]

I'm trying to send my data via Postman as x-www-form-urlencoded and as form-data.

But when I debug this code, I see they are all NULL.

Attribute [JsonProperty("body-plain")] didn't help me.

How can I bind these params?

I think @DavidG meant specifically how are you sending them, like via Postman? What does the actual request body look like? — Chris Pratt
– Chris Pratt, Commented Feb 25, 2019 at 14:18
Off the bat, what you're passing for attachments won't work at all. If you're going x-www-form-urlencoded, you've got to go all the way, which means having separate params for each property of each attachment, i.e. attachments[0].Url, attachments[0].ContentType, etc. — Chris Pratt
– Chris Pratt, Commented Feb 25, 2019 at 14:20
Okay, attachments[0].url works fine, but what about body-html or attachments[0].content-type? — A. Gladkiy
– A. Gladkiy, Commented Feb 25, 2019 at 14:38

Ryan · Accepted Answer · 2019-02-26 07:51:19Z

1

Try to use [ModelBinder(Name="name")] to specify a name for binding data

public class NotifyInput
{
    [ModelBinder(Name = "body-plain")]
    public string BodyPlain { get; set; }
    [ModelBinder(Name = "body-html")]
    public string BodyHtml { get; set; }

    public List<Attachment> Attachments { get; set; }
}
public class Attachment
{
    public int Size { get; set; }

    public string Url { get; set; }

    public string Name { get; set; }

    [ModelBinder(Name = "content-type")]
    public string ContentType { get; set; }

}

answered Feb 26, 2019 at 7:51

Ryan

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1 Comment

A. Gladkiy Over a year ago

My class NotifyInput is in separate project (.NET Standard) so I can't use Microsoft.AspNetCore.Mvc namespace here.

user8762691 · Accepted Answer · 2019-02-25 15:30:28Z

0

I played around with this and discovered that because you're passing a x-www-form-urlencoded to the endpoint, setting [JsonProperty("body-plain")] won't work; because you aren't sending Json.

So to pass those values you have to use the exact names on the models (case insensitive, but no hyphens). So, passing the following

bodyplain:123
bodyhtml:<p>123</p>

should work. attachments[0].content-type also has to become attachments[0].ContentType

answered Feb 25, 2019 at 15:30

user8762691

1 Comment

A. Gladkiy Over a year ago

Unfortunately, I can't change param names.

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