Restrict Asp.Net Web API numeric value bindings to base 10

Question

In an Asp.Net Web API controller I have, there is a PostAsync method that bind the request JSON body to a model class.

E.g.:

public class EmployeesController : ApiController
{
   ...
   public async Task<HttpResponseMessage> PostAsync([FromBody] Employee employee)
   {
      ...
   }
   ...
}

The Employee model class contains a numeric property, Height:

public class Employee
{
   ...
   public decimal Height { get; set; }
   ...
}

The problem is that when posting to the above controller action with request payload that contains a Height value with a leading zero, the FromBodyAttribute binder automatically converts the value to octal base, e.g.: 010 is translated as the value 8 in decimal base.

Sample request body:

{
   ...
   "Height": 010,
   ...
}

How can I prevent the conversion to an octal base?

What I've tried so far:

1. Implement a PropertyBindAttribute like described in this blog post, but the attribute receives the value post conversion to Octal base, so it's too late in the binding-life-cycle to use this approach
2. Convert the property to string type, and use a custom ValidationAttribute to validate the string is format match a numeric decimal base value, then converting the value to decimal and assigning it to another decimal property / backing-field

Answer 1

Why are you sending values with leading zeros? That's not a number as defined in JSON. Strictly according to the standard it's simply invalid JSON, but some parsers will be lenient and interpret it as an octal, which seems to be what is happening here.

So, .NET doesn't think you sent a standard decimal, which is why it interprets it like that. You could do the the validation via a string as a workaround, but really the caller should understand the correct format in which to send data.

P.S. This question is also relevant to the issue: Why is JSON invalid if an integer begins with 0