CODEWITHSUNDEEP
asp.net-coreasp.net-core-mvc
hnafar
hnafar

Reputation: 611

Read raw Request.Body in Asp.Net Core MVC Action with Route Parameters

I need to process the raw request body in and MVC core controller that has route parameters

[HttpPut]
[Route("api/foo/{fooId}")]
public async Task Put(string fooId)
{
   reader.Read(Request.Body).ToList();
   await _store.Add("tm", "test", data);
}

but It seems like the model binder has already consumed the request stream by the time it gets to the controller.

If I remove the route parameters, I can then access the request stream (since the framework will no longer process the stream to look for parameters). How can I specify both route parameters and be able to access Request Body without having to manually parse request URI etc.?

I have tried decorating my parameters with [FromRoute] but it had no effect.

How can I get the framework to bind paramters from Uri, QueryString, etc. but leave the request body to me?

Upvotes: 3

Views: 4504

Answers (2)

Samuel Jack
Samuel Jack

Reputation: 33290

Define this attribute in your code:

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public class DisableFormValueModelBindingAttribute : Attribute, IResourceFilter
{
   public void OnResourceExecuting(ResourceExecutingContext context)
   {
       var factories = context.ValueProviderFactories;
       factories.RemoveType<FormValueProviderFactory>();
       factories.RemoveType<JQueryFormValueProviderFactory>();
    }

    public void OnResourceExecuted(ResourceExecutedContext context)
    {
    }
}

If you're targeting .Net Core 3 you also need to add

factories.RemoveType<FormFileValueProviderFactory>();

Now decorate your action method with it:

[HttpPut]
[Route("api/foo/{fooId}")]
[DisableFormValueModelBinding]
public async Task Put(string fooId)
{
  reader.Read(Request.Body).ToList();
  await _store.Add("tm", "test", data);
}

The attribute works by removing Value Providers which will attempt to read the request body, leaving just those which supply values from the route or the query string.

HT @Tseng for the link Uploading large files with streaming which defines this attribute

Upvotes: 2

hnafar
hnafar

Reputation: 611

As I suspected the root cause was MVC inspecting the request body in order to try to bind route parameters. This is how model binding works by default for any routes that are not parameter-less, as per documentation.

The framework however does this only when the request content type is not specified, or when it is form data (multipart or url-encoded I assume).

Changing my request content-type to any thing other than form data (e.g. application/json) I can get the framework to ignore the body unless specifically required (e.g. with a [FromBody] route parameter). This is an acceptable solution for my case since I am only interested accepting JSON payloads with content-type application/json.

Implementation of DisableFormValueModelBindingAttribute in Uploading large files with streaming pointed out by @Tseng seems to be a better approach however, so I will look into using that instead, for complete

Upvotes: 1

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