Getting Null on Patch Requests

[amarwadi]

Hello,
Is there anything special I need to do other than adding the Nuget Package and using the JsonPatchDocument on the [FromBody] attribute for the HttpPatch methods on Web API? For some reason, no matter what I do, I always get a null object. Here's how my call looks like:

     [Route("sites/{siteId}/affiliates/{affiliateId}/codes/{codeId}/commissions/{id}"), HttpPatch,
     ResponseType(typeof(BoolResult)), ValidateSiteId()]
    public async Task<IHttpActionResult> AddTieredCommission(long siteId, long affiliateId, string codeId,
       string id, [FromBody] JsonPatchDocument<AddTieredCommissionModel> model)
    {
        
        return Ok();
    }

I am using ASP.NET Web API (not on ASP.NET Core). Any help would be appreciated.

Anup

[LouisChiero]

Are you setting the request's Content-Type as "application/json-patch+json"?

[Swoogan]

I had this same issue. Make sure that the JSON body of your request is formatted correctly. I was using RestSharp, which serializes using a formatter that doesn't respect the [SerializeAs] attributes on JsonPatchDocument. Using fiddler I was able to see what was being passed in the request body and with Insomnia I could confirm that it didn't work. By serializing with Newtsoft.Json, I got out put that looked like the json patch RFC.

[KevinDockx]

Closing issue as it seems to be solved. If you experience additional problems, feel free to reopen.

[dpescatore]

How this was resolved? I have the same problem.
I've tried adding
config.Formatters.JsonFormatter.SupportedMediaTypes.Add( new MediaTypeHeaderValue("application/json-patch+json"));
And both with simple "application/json" but I always have a null object on server.

Here's signature of my api method

public IHttpActionResult PatchEntity(int id, [FromBody]JsonPatchDocument<Entity> entity)

and here my simple JSONPatch sent by restlet client.

{ "op": "replace", "path": "/seconds", "value": "12" }

Any help on this?

Thanks,
Daniele

[dpescatore]

I solved by myself.
A correct JSONPatch body must contain an array of operations.
Changing my request in:

[{ "op": "replace", "path": "/seconds", "value": "12" }]

works like a charm.

Daniele

[jvargasvillegas]

Thanks.
I was doing same mistake

Bad code
{
{
"op": "replace",
"path": "/name",
"value": "Updated - Central Park"
}
}

Fixed code
[
{
"op": "replace",
"path": "/name",
"value": "Updated - Central Park"
}
]