Convert int values (1,0) to boolean using FromQueryAttribute

Question

I have this API method:

  [HttpGet("foo")]
  public IActionResult Foo([FromQuery] bool parameter)
  {
    // ...
  }

And I know I can call my method like this and it will work:

.../foo?parameter=true

But I also want to support numeric values 0 and 1 and call my method like this:

.../foo?parameter=1

But when I try, I get this exception inside System.Private.CoreLib

System.FormatException: 'String '1' was not recognized as a valid Boolean.'

Is this even possible?

Answer 1

Because the default ModelBinder didn't support 1 to bool, we can try to create our own binding logic by implementing IModelBinder interface.

public class BoolModelBinder : IModelBinder {
    public Task BindModelAsync(ModelBindingContext bindingContext) {
        var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName).FirstValue;

        if (int.TryParse(value, out var intValue)) {
            bindingContext.Result = ModelBindingResult.Success(intValue == 1);

        } else if (bool.TryParse(value, out var boolValue)) {
            bindingContext.Result = ModelBindingResult.Success(boolValue);

        } else if (string.IsNullOrWhiteSpace(value)) {
            bindingContext.Result = ModelBindingResult.Success(false);
        } 
        
        return Task.CompletedTask;
    }
}

then we can use ModelBinderAttribute to assign our BoolModelBinder type as this binder.

[HttpGet("foo")]
public IActionResult Foo([ModelBinder(typeof(BoolModelBinder))] bool parameter)
{
  // ...
}

Answer 2

the easiest way is to change an input parameter type to string

[HttpGet("foo")]
  public IActionResult Foo([FromQuery] string parameter)
  {
    if( parameter=="true" || parameter=="1") ....
    else if( parameter=="false" || parameter=="0") ....
    else ....
  }