Can I add [FromBody] parameter with backward compatibility?

Question

I have endpoint which doesn't have [FromBody] parameter:

    [HttpPost("{id:int}/publish")]
    public async Task<IActionResult> Publish()
    {
        <do some stuff>
        return Ok();
    }

But now I need to add [FromBody] parameter in the way that old code is still able to use this endpoint without parameter:

    [HttpPost("{id:int}/publish")]
    public async Task<IActionResult> Publish([FromBody] PublishRequest request)
    {
        <do some stuff>
        return Ok();
    }

But if I add it in this way and try to call this endpoint with empty body, i got 415 (Unsupported Media Type) response back.

I want to make this change backward compatible. So it should be possible to use this endpoint without request body and content-type header. Is is possible?

Just curious: where does the ID parameter go? How are you referring to it in your ? I would have expected it on the method signature. — Richard, Jun 02 '20 at 10:29
It seems that optional `FromBody` parameters are not supported ATM, but it seems in [this](https://github.com/dotnet/aspnetcore/issues/6878#issuecomment-595515755) github issue a workaround is posted. — Guru Stron, Jun 02 '20 at 10:33
@GuruStron, It's exactly what i need! You can post your comment as answer and i will upvote it! — ant, Jun 02 '20 at 11:05
Your question looks a lot like this one: https://stackoverflow.com/questions/44538772/asp-net-core-form-post-results-in-a-http-415-unsupported-media-type-response Does your solution allow for a [FromForm] in stead of [FromBody]? — Richard, Jun 02 '20 at 10:40

score 2 · Accepted Answer · answered Jun 02 '20 at 11:06

It seems that optional FromBody parameters are not supported ATM, but in this github issue was posted a possible workaround:

public class SomeClassModelBinder : IModelBinder
{
    public async Task BindModelAsync(ModelBindingContext bindingContext)
    {
        var stream = bindingContext.HttpContext.Request.Body;
        string body;
        using (var reader = new StreamReader(stream))
        {
            body = await reader.ReadToEndAsync();
        }
        var someClass = JsonConvert.DeserializeObject<SomeClass>(body);

        bindingContext.Result = ModelBindingResult.Success(someClass);
    }
}

[FromBody, ModelBinder(BinderType = typeof(SomeClassModelBinder))] SomeClass request,

score 0 · Answer 2 · answered Jun 02 '20 at 10:50

0

You can make the PublishRequest optional.

[HttpPost("{id:int}/publish")]
public async Task<IActionResult> Publish([FromBody] PublishRequest? request)
{
    // <do some stuff>
    return Ok();
}

answered Jun 02 '20 at 10:50

Marius Steinbach

548
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Can I add [FromBody] parameter with backward compatibility?

2 Answers2