How to discern between model binding errors and model validation errors?

Question

I\'m implementing a REST API project using ASP.NET Core MVC 2.0, and I\'d like to return a 400 status code if model binding failed (because the request is syntactically wron

Answer 1

Add attribute below in your project

public class ValidateModelAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        base.OnActionExecuting(context);

        if (!context.ModelState.IsValid)
            context.Result = new BadRequestObjectResult(new
            {
                message = context.ModelState.Values.SelectMany(v => v.Errors.Select(e => e.ErrorMessage))
            });
    }
}

Change your api like this

[HttpPut("{id}")]
[ValidateModel]
public async Task UpdateAsync(
    [FromRoute] int id,
    [FromBody] ThingModel model)

id contains a non-digit => 400

model does not pass annotation validation inside => 400

if you want to reject unacceptable values in model with 422 code, implement in your controller