Restore AJAX handling for ASP.NET Core to previous functionality - asp.net-core

Question

In previous MVC5 and below, you could make an ajax call that unwrapped the parameters properly:
JS:
$.post('/controller/endpoint',{intparam: 1, strparam: 'hello'})
CS:
public ActionResult endpoint(int intparam, string strparam){}
In the new aspnetcore, it has changed:
CS:
public CustomClassWrapper{
public int intparam {get;set;}
public string stringparam {get;set;}
}
public ActionResult endpoint([FromBody]CustomClassWrapper item){}
To sum it up, in the new framework, you need to write a wrapper class and can only pass one [FromBody] parameter to the method. Previously, the params would be unwrapped by variable name correctly.
So, i'm trying to re-implement this functionality in an aspnetcore middleware component. I'm having difficulty in how to accomplish calling the controller method properly with the parameters.
My current cut-down code:
public async Task Invoke(HttpContext context)
{
if (IsAjaxRequest(context.Request))
{
try
{
string bodyContent = new StreamReader(context.Request.Body).ReadToEnd();
var parameters = JsonConvert.DeserializeObject(bodyContent);
///What to do here?
}
catch (Exception ex)
{
throw new Exception("AJAX method not found ", ex);
}
}
else
{
await _next(context);
}
}
I'm really just not sure about what to do after deserializing the parameters. I have the URL for the endpoint and also the params correctly. Just need to know how to call the method and return the result as JSON. Should i be using Reflection to get the controller method? Or is there a better way using MVC?

Answer 1

Try implement custom IModelBinder.
public class BodyFieldModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
bindingContext.HttpContext.Request.EnableRewind(); // required to read request body multiple times
var inputStream = bindingContext.HttpContext.Request.Body;
if (inputStream.Position != 0L)
inputStream.Position = 0;
var bodyValue = new StreamReader(inputStream, Encoding.UTF8).ReadToEnd();
var jsonObject = (JObject)JsonConvert.DeserializeObject<object>(bodyValue);
if (jsonObject.TryGetValue(bindingContext.FieldName, out var jToken))
{
var jsonSerializer = JsonSerializer.Create();
var result = jToken.ToObject(bindingContext.ModelType, jsonSerializer);
bindingContext.Result = ModelBindingResult.Success(result);
return Task.CompletedTask;
}
bindingContext.Result = ModelBindingResult.Failed();
return Task.CompletedTask;
}
}
Be careful, the code above lacks error handling and etc.
And use it like this:
[HttpPost]
public IActionResult Endpoint([ModelBinder(typeof(BodyFieldModelBinder))] int intparam)
Also you could implement custom attribute to reduce complexity of declaration:
public class BodyFieldAttribute : ModelBinderAttribute
{
public BodyFieldAttribute()
: base(typeof(BodyFieldModelBinder))
{
}
}

Answer 2

it's very simple thing i don't know why it not working at your end
JS
$.post('actionMethodURl', { FirstName: '1', LastName: 'hello' }).done(Successfunction);
CS
[HttpPost]
public ActionResult endpoint(string FirstName,string LastName)
{
object Message = string.Empty;
if (ModelState.IsValid)
{
Message = "Pass";
}
else
{
Message = ModelState.Errors();
}
return Json(Message);
}