Reading Fromuri and Frombody at the Same Time

Reading FromUri and FromBody at the same time

A post body is typically a URI string like this:

Message=foobar&TestingMode=true

You have to make sure that the HTTP header contains

Content-Type: application/x-www-form-urlencoded

EDIT: Because it's still not working, I created a full example myself.

It prints the correct data.

I also used .NET 4.5 RC.

// server-side
public class ValuesController : ApiController {
    [HttpPost]
    public string PushMessage([FromUri] string x, [FromUri] string y, [FromBody] Person p) {
        return p.ToString();
    }
}

public class Person {
    public string Name { get; set; }
    public int Age { get; set; }

    public override string ToString() {
        return this.Name + ": " + this.Age;
    }
}

// client-side
public class Program {
    private static readonly string URL = "http://localhost:6299/api/values/PushMessage?x=asd&y=qwe";

    public static void Main(string[] args) {
        NameValueCollection data = new NameValueCollection();
        data.Add("Name", "Johannes");
        data.Add("Age", "24");

        WebClient client = new WebClient();
        client.UploadValuesCompleted += UploadValuesCompleted;
        client.Headers["Content-Type"] = "application/x-www-form-urlencoded";
        Task t = client.UploadValuesTaskAsync(new Uri(URL), "POST", data);
        t.Wait();
    }

    private static void UploadValuesCompleted(object sender, UploadValuesCompletedEventArgs e) {
        Console.WriteLine(Encoding.ASCII.GetString(e.Result));
    }
}

Are [FromBody] and [FromUri] mutually exclusive?

In your first implementation

public void PostInventoryItem([FromBody] string serialNum, [FromUri] InventoryItem ii)

{}

the value of serialNum is null as expected, because [FromBody] was trying to look for serialNum in the body of your message.

This is the definition of the attribute from MSDN:

FromBodyAttribute Class

An attribute that specifies that an action parameter comes only from
the entity body of the incoming HttpRequestMessage.

ASP.NET Core MVC Mixed Route/FromBody Model Binding & Validation

You can remove the [FromBody] decorator on your input and let MVC binding map the properties:

[HttpPost("/test/{rootId}/echo/{id}")]
public IActionResult TestEcho(TestModel data)
{
    return Json(new
    {
        data.Id,
        data.RootId,
        data.Name,
        data.Description,
        Errors = ModelState.IsValid ? null : ModelState.SelectMany(x => x.Value.Errors)
    });
}

More info:
Model binding in ASP.NET Core MVC

UPDATE

Testing

UPDATE 2

@heavyd, you are right in that JSON data requires [FromBody] attribute to bind your model. So what I said above will work on form data but not with JSON data.

As alternative, you can create a custom model binder that binds the Id and RootId properties from the url, whilst it binds the rest of the properties from the request body.

public class TestModelBinder : IModelBinder
{
    private BodyModelBinder defaultBinder;

    public TestModelBinder(IList<IInputFormatter> formatters, IHttpRequestStreamReaderFactory readerFactory) // : base(formatters, readerFactory)
    {
        defaultBinder = new BodyModelBinder(formatters, readerFactory);
    }

    public async Task BindModelAsync(ModelBindingContext bindingContext)
    {
        // callinng the default body binder
        await defaultBinder.BindModelAsync(bindingContext);

        if (bindingContext.Result.IsModelSet)
        {
            var data = bindingContext.Result.Model as TestModel;
            if (data != null)
            {
                var value = bindingContext.ValueProvider.GetValue("Id").FirstValue;
                int intValue = 0;
                if (int.TryParse(value, out intValue))
                {
                    // Override the Id property
                    data.Id = intValue;
                }
                value = bindingContext.ValueProvider.GetValue("RootId").FirstValue;
                if (int.TryParse(value, out intValue))
                {
                    // Override the RootId property
                    data.RootId = intValue;
                }
                bindingContext.Result = ModelBindingResult.Success(data);
            }

        }

    }
}

Create a binder provider:

public class TestModelBinderProvider : IModelBinderProvider
{
    private readonly IList<IInputFormatter> formatters;
    private readonly IHttpRequestStreamReaderFactory readerFactory;

    public TestModelBinderProvider(IList<IInputFormatter> formatters, IHttpRequestStreamReaderFactory readerFactory)
    {
        this.formatters = formatters;
        this.readerFactory = readerFactory;
    }

    public IModelBinder GetBinder(ModelBinderProviderContext context)
    {
        if (context.Metadata.ModelType == typeof(TestModel))
            return new TestModelBinder(formatters, readerFactory);

        return null;
    }
}

And tell MVC to use it:

services.AddMvc()
  .AddMvcOptions(options =>
  {
     IHttpRequestStreamReaderFactory readerFactory = services.BuildServiceProvider().GetRequiredService<IHttpRequestStreamReaderFactory>();
     options.ModelBinderProviders.Insert(0, new TestModelBinderProvider(options.InputFormatters, readerFactory));
  });

Then your controller has:

[HttpPost("/test/{rootId}/echo/{id}")]
public IActionResult TestEcho(TestModel data)
{...}

Testing

You can add an Id and RootId to your JSON but they will be ignored as we are overwriting them in our model binder.

UPDATE 3

The above allows you to use your data model annotations for validating Id and RootId. But I think it may confuse other developers who would look at your API code. I would suggest to just simplify the API signature to accept a different model to use with [FromBody] and separate the other two properties that come from the uri.

[HttpPost("/test/{rootId}/echo/{id}")]
public IActionResult TestEcho(int id, int rootId, [FromBody]TestModelNameAndAddress testModelNameAndAddress)

And you could just write a validator for all your input, like:

// This would return a list of tuples of property and error message.
var errors = validator.Validate(id, rootId, testModelNameAndAddress); 
if (errors.Count() > 0)
{
    foreach (var error in errors)
    {
        ModelState.AddModelError(error.Property, error.Message);
    }
}

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