>Hi everybody,
>
>I am wondering if anyone did server-side validations of input fields directly (e.g. not on submit). If yes, can you provide examples / point me to the good papers on the topic?
>
>In particular, I'd like to validate barcode (or UPC) for uniqueness as the user enters it.
>
>I wrote the following in my service
>
>

>ItemService.prototype.checkCodeUniqueness = function (code) {
>        var deferred = services.Deferred;
>
>        services.Http.get(urlPath + '/checkCodeUniqueness/' + encodeURIComponent(code))
>            .then(function (data) {
>                deferred.resolve(data.data);
>            });
>
>        return deferred.promise;
>    };

>
>but I don't know if this is correct (e.g. how would I decode in C# and how would I implement the validations on the input).
>
>I would appreciate suggestions / code examples.
>
>Thanks in advance.

Not sure what you actually want to check, 'uniqueness' implies checking that it's not already stored, 'validity' suggests you just want to check the length and checksum? The latter could easily be done with client side javascript.
Also no clear where/when you are calling checkCodeUniqueness() ?