如何为Int64创建RangeValidator？ BigInt？ 长？

Question

So I'm trying to use the RangeValidator to ensure the minimum and maximum value of Int64 is validated. But, the only or closest option that I seem to have is Double.

Dim Range As New RangeValidator
Range.ControlToValidate = "..."
Range.Type = ValidationDataType.Double
Range.MinValue = Int64.MinValue.ToString
Range.MaxValue = Int64.MaxValue.ToString

I don't want to use a custom validator. I suppose I could use some crazy regular expression.. but just trying to understand why I can't do this.

For example, the max value of Int64 is:

9223372036854775807

But this validates:

9223372036854775808
9223372036854775810
9223372036854775899

It will not validate if I jump up a larger number:

9223372036854799999

I'm assuming it's due to some conversion taking place for a Double.

I do see there's a LongValidator in System.Configuration, but I'm trying to avoid creating a CustomValidator type if at all possible and it's a different validate type, as in not intended for use like RangeValidator.

All of this is more so for learning purposes than anything else. I'm aware I can jump through other hoops but hoping to get better clarity.

Tagged C# as well. Ignore my vb.net example.. not really important based on the question. Will convert any code either way.

Answer 1

I found a plausible answer on a forum by PLBlum

I want to clarify something. RangeValidator does not use a regularexpression to validate a double. It uses a regular expression to extract the digits and decimal character out of the string. It then converts the result into an actual number using the javascript parseFloat() function. If that function cannot convert, the RangeValidator knows the value was not acceptable to javascript.

I suspect that the problem is that the value you are assigning to MaximumValue is too large for javascript's floating point. I think both .net's Double and javascript are 80bit floating point but its possible they are slightly different at the min and max range. In any case, I recommend changing your code like this:

• Use a CompareValidator, Operator=DataTypeCheck, Type=Double. It will report an illegal value due to the format or its too big for an 80 bit number.

• Use another CompareValidator, Operator=GreaterThanEqual, Type=Double, ValueToCompare= your minimum double. This will report an error if anything is below the minimum. The max was handled in the other validator.

Maybe that explains why it is validating incorrectly.

Answer 2

Unless someone else wants to chime in, realistically there's one way I found to do this, and that's with a custom validator. There's a function in System.configuration that allows the ability to check if a value is a valid "Long". The problem is, if you want client-side validation it seems the only valid option is to use a regex. Otherwise, the number is just too big and JavaScript parses it as a float, as Sam mentioned.

So, I ended up using a regex as to gain client-side and server-side validation.