ASP.net WebAPI using [FromUri] Attribute problems

Question

This's my controller code:

[HttpGet]
        [Route()]
        public async Task<List<GetCategoryTreeOutputDto>> GetDatasetCategoryTreeAsync([FromUri(Name = "")] GetCategoryTreeInputDto input)
        {
            return await _category.GetDatasetCategoryTreeAsync(input);
        }
public class GetCategoryTreeInputDto
{
    /// <summary>
    /// 名称
    /// </summary>
    public string Name { get; set; }
    public int? ParentId { get; set; }
}

and I get an error:

When I assign a parameter value,it works,So I have to give a value to use it?But these parameters don't always need to be assigned value.

i assigned value,it works