Asp.net CORE 3.0 web API method always receives NULL value

Question

I am having an issue with my Angular app. Basically the issue is that it displays a 500 server error.

These are my methods:

/*Product Service*/
addNewProduct(newProduct: Product): Observable<Product> {
console.log(newProduct);
return this.http.post<Product>(this.productUrl, newProduct);
}


/*Product-list.component.ts*/
onSubmit() {
let newProduct = this.insertForm.value;
console.log(newProduct);
this.productService.addNewProduct(newProduct).subscribe(
  result => {
    this.productService.clearCache();
    this.products$ = this.productService.getProducts();

    this.products$.subscribe(newlist => {
      this.products = newlist;
      this.modalRef.hide();
      this.insertForm.reset();

    });
    console.log("New Product added");
  },
  error => {
    console.error(error);
  }
)}

And this is my C# method

[HttpPost("[action]")]
    [Authorize(Policy = "RequiredAdministratorRole")]
    public async Task<ActionResult> AddProduct([FromBody] Product formdata)
    {
        var newproduct = new Product
        {
            Name = formdata.Name,
            Description = formdata.Description,
            ImageURL = formdata.ImageURL,
            OutOfStock = formdata.OutOfStock,
            Price = formdata.Price
        };

        await _db.Products.AddAsync(newproduct);
        await _db.SaveChangesAsync();

        return Ok(new JsonResult("The product has been added successfully"));
    }

And the error is the following:

HttpErrorResponse {headers: HttpHeaders, status: 500, statusText: "OK", url: "https://localhost:44382/api/product/addproduct", ok: false, …}

POST https://localhost:44382/api/product/addproduct 500

Can somebody help me?

Thanks in advance.

HeyBaldur · Accepted Answer · 2019-12-25 17:20:18Z

1

I found the issue by myself, the problem basically was that the endpoint expects to receive a well structured model, however in the HTML code there was an input with a 'text' type instead 'number', this seemed to affected the Angular interface. If somebody needs a asp.net core 3.1 with Angular 8 sample application please feel free to clone my repo to verify my code and learn more.

https://github.com/gitrodo/asp-net-core-angular-8

Thanks.

answered Dec 25, 2019 at 17:20

HeyBaldur

5731 gold badge7 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Venkata K. C. Tata Over a year ago

Bro, you saved my day. I added the JsonStringInputFormatter and it started working.

Matt Hensley · Accepted Answer · 2019-12-20 16:33:07Z

0

Your error is most likely caused by formdata not deserializing correctly, causing the NullReferenceException when accessing the members.

You would be able to catch this by checking if the ModelState.IsValid property is true before trying to access the members of formdata.

[HttpPost("[action]")]
    [Authorize(Policy = "RequiredAdministratorRole")]
    public async Task<ActionResult> AddProduct([FromBody] Product formdata)
    {
        if (ModelState.IsValid)
        {
            var newproduct = new Product
            {
                Name = formdata.Name,
                Description = formdata.Description,
                ImageURL = formdata.ImageURL,
                OutOfStock = formdata.OutOfStock,
                Price = formdata.Price
            };

            await _db.Products.AddAsync(newproduct);
            await _db.SaveChangesAsync();

            return Ok(new JsonResult("The product has been added successfully"));
        }
        else
        {
            // Let the client know the data they passed was not valid.
            return BadRequest();
        }
    }

answered Dec 20, 2019 at 16:33

Matt Hensley

8939 silver badges18 bronze badges

7 Comments

HeyBaldur Over a year ago

I have debugged the method but it seems it's receiving a null value in the 'formdata'

Matt Hensley Over a year ago

Ok, this answer might be able to help you out with identifying why it is null. stackoverflow.com/questions/14084746/…

HeyBaldur Over a year ago

Let me check it out. Thanks @Matt

HeyBaldur Over a year ago

Unfortunately I am still having issues. I have added JSON.stringify(newProduct), this.httpOptions but it now displays an 400 error. Here is my repo, github.com/gitrodo/asp-net-core-angular-8/tree/Development, maybe you can help me out with this.

HeyBaldur Over a year ago

I am not sure if the asp.net core version might affect. I am using the 3.0 version.

|

Collectives™ on Stack Overflow

Asp.net CORE 3.0 web API method always receives NULL value

2 Answers 2

1 Comment

7 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

7 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related