Can I customize error messages for values higher than allowed?

Question

I want to set a custom messagem when a higher value than allowed is informed, at swagger. I have the following method in my controller:

public async Task<IActionResult> MyMethod(short someValue)

The max value for short in .Net is 32767, if I pass a higher value, I got the error message: "The value '999999' is not valid.", is there a way to customize that message?

Answer 1

It's a modelbinding error not model validation error,you may try set here:

builder.Services.AddControllers(op => op.ModelBindingMessageProvider.SetNonPropertyAttemptedValueIsInvalidAccessor(input => input+" invalid")) ;

Result:

For more detailed error message, you need to custom model binder,for example:

public class MyBinder : IModelBinder
    {
        public Task BindModelAsync(ModelBindingContext bindingContext)
        {
            var modelName = bindingContext.ModelName;

            // Try to fetch the value of the argument by name
            var valueProviderResult = bindingContext.ValueProvider.GetValue(modelName);
            if (valueProviderResult == ValueProviderResult.None)
            {
                return Task.CompletedTask;
            }

            bindingContext.ModelState.SetModelValue(modelName, valueProviderResult);

            var value = valueProviderResult.FirstValue;

            if (!short.TryParse(value, out var id))
            {
                // add the logical compare the value and so on
                bindingContext.ModelState.TryAddModelError(
                    modelName, value+" is not valid for short.");

                return Task.CompletedTask;
            }


            return Task.CompletedTask;
        }
    }

Apply the modelbinder :

[ModelBinder(BinderType = typeof(MyBinder))] short someValue

Result: