Asp.net Core Post parameter is always null
Solution 1
I just had to correct the double quotes in your POST request and it worked. Try this:
{"Ean":"1122u88991","Name":"Post test","Description":"Post test desc"}
See screenshot below.
Solution 2
I experience a similar problem but I had no check for the validity of the ModelState
as the OP. When this happens, inspecting it in debug mode will likely point you to what's wrong with the model:
In this example I was using an invalid string 'A'
as test value for a Guid
property, so the model was always null.
Solution 3
Had the same problem. It turned out that I had no public parameterless constructor for class of incoming instance. In this case, Product
had only protected constructors and parameter was always null no matter what. Hope it helps somebody.
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martinv
Updated on June 04, 2022Comments
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martinv over 1 year
I'm sending POST from fiddler:
POST http://localhost:55924/api/Product HTTP/1.1 User-Agent: Fiddler Host: localhost:55924 Content-Type: application/json; charset=utf-8 Content-Length: 84 {"Ean″:”1122u88991″,”Name″:”Post test″,"Description":"Post test desc"}
But Post method always gets null.
// POST api/Product [HttpPost] public IActionResult PostProduct([FromBody]Product product) { if (!ModelState.IsValid) { return BadRequest(ModelState); } _repo.Add(product); return CreatedAtRoute("GetToode",product); }
When I use [FormBody] product is always null, when not using it product is valued but with all fields being null. Product class is simple.
public class Product { public int ProductID { get; set; } public string EAN { get; set; } public string Name { get; set; } public string Description { get; set; } public int? CategoryID { get; set; } }
i tried adding NullValueHandling to ConfigureServices as proposed in post but no use.
services.AddMvc() .AddJsonOptions(jsonOptions => { jsonOptions.SerializerSettings.NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore; });
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Fabricio Koch about 7 yearstry it sending all properties. Include
ProductID
andCategoryID
.
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martinv about 7 yearsHonestly I feel so so dumb right now, that I didn't noticed it myself.
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jcespinoza over 4 yearsIt is not clear what quotes this answer refers to because the question was since edited a few times. FYI, OP used a mix of
″ ”
and"
characters in the original request body. -
Gimmly over 3 yearsThank you for the great answer! I was shooting in the dark before stumbling upon this