[Ur] Handling the POST request

Tue May 9 23:42:31 EDT 2017

2017-05-10 9:34 GMT+06:00 Jeevjyot Chhabda <jeevsingh at mail.fresnostate.edu>:
> Greetings,
>
> I was wondering if there is way to handle the bogus values in the POST
> request or of the wrong type? Would bogus values will result in fatal error?
> How we catch them and show the appropriate error in Ur/Web, more sort of
> validation.
>

While I don't know the details, you could probably start off at this
demo (pasted straight from the Ur/Web's online demo):

fun handler r = return <xml><body>
  <table>
    <tr> <th>A:</th> <td>{[r.A]}</td> </tr>
    <tr> <th>B:</th> <td>{[r.B]}</td> </tr>
    <tr> <th>C:</th> <td>{[r.C]}</td> </tr>
  </table>
</body></xml>

fun main () = return <xml><body>
  <form>
    <table>
      <tr> <th>A:</th> <td><textbox{#A}/></td> </tr>
      <tr> <th>B:</th> <td><textbox{#B}/></td> </tr>
      <tr> <th>C:</th> <td><checkbox{#C}/></td> </tr>
      <tr> <th/> <td><submit action={handler}/></td> </tr>
    </table>
  </form>
</body></xml>

In [handler], the type of [r] is [{ A : string, B : string, C : bool
}]. You could put some checks prior to returning the HTML result,
e.g.:

fun handler r =
case (@read read_int r.A) of
None => return <xml><body>
  <p>Unable to parse A!</p>
</body></xml>
| Some => ... (* same as before *)

I'm sorry, I have not tested the above code, but the idea should be
clear enough.

>
>
> thanks,
>
> Jeevjyot
>
>
>
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-- 
Cheers,
Artyom Shalkhakov