MVC：将类型为'double'的ViewData对象传递给数字输入字段

Question

I'm trying to pass a ViewData object of type double to an input field of type number with 1 decimal place. But the input field keeps empty. What am I doing wrong?

<p>
   Debiet factor: <input name="FlowFact" type="number" value="@ViewData["FlowFact"]"  step="0.1" autocomplete="off">
   @String.Format("{0:N1} m³/h", @ViewData["FlowFact"]) <!--Result = 3,1 m³/h-->
</p>

Answer 1

The issue you're facing is what the ViewData["FlowFact"] is returning, which according to your @String.Format("{0:N1} m³/h", @ViewData["FlowFact"]) <!--Result = 3,1 m³/h--> it's 3,1 .

That is not recognised as a number so it won't work. Either return a whole number or a decimal number. So instead of a 3,1 , return a 3.1 or just a 3 . Otherwise change the input type to accept what you are passing.

Answer 2

I found the solution thanks to jamiedanq.

In my controller I was writing a double value to the @ViewData["FlowFact"] object. But in my view it was returning a value 3,0999 , which is not a correct value for the input type 'Number' because of the ",".

Instead of passing a double value to the object I've changed it to pass a string value and replace the "," with a ".":

Controller:

 @ViewData["FlowFact"] = @String.Format("{0:N1}", MyDoubleValue).Replace(",","."); 

View:

 <p> Debiet factor: <input name="FlowFact" type="number" value="@ViewData["FlowFact"]" step="0.1" autocomplete="off"> </p>