ASP.NET Core is receiving string input as null from android retrofit client

I am trying to call my backend using Retrofit client from Android Studio and my backend is ASP.NET Core 3.1, the route specified is [Route("api/getProducts")]. Retrofit client seems to call my route just fine, but after string searchStr is received, the searchStr is null. I am not sure why this is happening.

When I use postman to test, it works just fine.

It doesnt seem to matter what string value I send with retrofit client, it is always null.

Here is my retrofit function:

private fun findProducts(inputStr: String) {          val paramObject = JSONObject()          paramObject.put("searchStr", inputStr)              val call = myApi.findProducts(paramObject.toString())          call.enqueue(object : Callback<ProductRes> {              override fun onResponse(call: Call<ProductRes>, response: Response<ProductRes>) {                  Log.e(TAG, "message onResponse: " + response.body()!!.message.toString())                  Log.e(TAG, "findProducts onResponse: " + response.body()!!.productList.asList())              }                override fun onFailure(call: Call<ProductRes>, t: Throwable) {                  Log.e(TAG, "findProducts onFailure: " + t.localizedMessage)              }          })      }  

Here is my IMyAPI.kt code:

@Headers("Content-Type: application/json")      @POST("api/getProducts")      fun findProducts(@Body searchStr: String?):Call<ProductRes>  

https://stackoverflow.com/questions/66937428/asp-net-core-is-receiving-string-input-as-null-from-android-retrofit-client April 04, 2021 at 10:04AM