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Custom Model Binder Provider always null .net core

I'm having a problem trying to get custom model binders to work as a query parameter like I have gotten to work previously in .net framework 4.7.

To ensure this wasn't a scenario where my object was too complex, I reduced the model to a simple string but even then I cannot get this to work.

I have a simple model I would like to be binded from query parameters.

public class SearchModel {
public string SearchTerms { get; set; }
}


And I have configured the ModelBinder and ModelBinderProvider as shown here like so.

public class TestModelBinder : IModelBinder {
public Task BindModelAsync(ModelBindingContext bindingContext) {
if (bindingContext.ModelType != typeof(SearchModel)) {
throw new ArgumentException($"Invalid binding context supplied {bindingContext.ModelType}");
}

var model = (SearchModel)bindingContext.Model ?? new SearchModel();

var properties = model.GetType().GetProperties();
foreach(var p in properties) {
var value = this.GetValue(bindingContext, p.Name);
p.SetValue(model, Convert.ChangeType(value, p.PropertyType), null);
}

return Task.CompletedTask;
}

protected string GetValue(ModelBindingContext context, string key) {
var result = context.ValueProvider.GetValue(key);

return result.FirstValue;
}
}

public class TestModelBinderProvider : IModelBinderProvider {
public IModelBinder GetBinder(ModelBinderProviderContext context) {
if (context == null) {
throw new ArgumentNullException(nameof(context));
}

if (context.Metadata.ModelType == typeof(SearchModel)) {
var returnType = new BinderTypeModelBinder(typeof(TestModelBinder));
return returnType;
}

return null;
}
}


As stated in the last step in Microsoft documentation I updated my ConfigureServices method in Startup.cs to include the BinderProvider.

services.AddMvc(options => {
options.ModelBinderProviders.Insert(0, new TestModelBinderProvider());
})
.SetCompatibilityVersion(CompatibilityVersion.Version_2_1);


But when I call my Search endpoint with a url such as "https://localhost:44387/api/testbinding?searchTerms=newSearch" I am always seeing a return of "request == null True" even though I see it properly hit the custom binding and bind correctly if I step through debugging, can anyone please point me in the right direction as to what I am doing wrong?

[Route("api/[controller]")]
[ApiController]
public class TestBindingController : ControllerBase {

[HttpGet()]
public IActionResult GetResult([FromQuery] SearchModel request) {
return Ok($"request == null {request == null}");
}

}


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