ASP.NET Core Api parameter is null

Question

I have an API controller which has actions to get and post data. and I am trying to access GetProductById meyhod from ajax bu productId parameter is always equals to zero (0). When I want to call GetAll method with GET method everything is fine. JavaScript code is like below

var product = JSON.stringify({ productId: id });
        $http({
            method: 'POST',
            contentType: 'application/json',
            url: '/api/Product/ProductInfo',
            data: product
        }).then(function successCallback(response) {
            console.log(response);
        }, function errorCallback(response) {
            console.log(response);
        });

And API Controller is like below

[Route("api/Product")]
public class ProductController : BaseController
{
    [HttpPost]
    [Route("ProductInfo")]
    public Product GetProductById([FromBody]int productId)
    {
        return UnitOfWork.GetRepository<Product>().FirstOrDefault(i => i.Id == productId);
    }
    [HttpGet]
    [Route("GetAll")]
    public string GetAll()
    {
        return "Can";
    }
}

Can anyone say why that case is happening?

Swagata Prateek · Accepted Answer · 2016-08-16 14:18:42Z

1

Although you are sending back a string representation of { productId: id } when the model is binded in the post method in the controller it is expecting an int. productId is barely the argument of that method, it doesn't define the parameter name you're supposed to send. Try sending just the id in the body instead of that json body { productId: id }.

If you want to send back a json body then the proper representation should be a class like the following for your post action

class ProductModel
{
    int productId;
}

This would essentially make you able to parse your json payload the way you send it now, of course you can opt for custom model binders but that would be an overkill.

For example, if the id is 123 just use 123 as body, not { productId: 123 }

answered Aug 16, 2016 at 14:18

Swagata Prateek

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4 Comments

Can PERK Over a year ago

I modified code. Neither I should call url like path?productId=1 nor I should use reference types instead of primitive types

Swagata Prateek Over a year ago

Cool. That's essentially the right way to go given it's a post. :) Although you can use a keyvalue pair in these cases, no extra classes necessary anyway.

Can PERK Over a year ago

KeyValuePair? how can i send it from json or is it clear to get from api action?

Swagata Prateek Over a year ago

Pardon me if I mislead you. I wanted to suggest something like the this. I can pretty much understand that I mislead you using KeyValuePair<TKey, TValue> types. Didn't intend to. :)

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