.NET validate dynamically created fields

Question

I'm working on a page where I have to dynamically add multiple fields. I've basically completed the job but I'm being held back by the validation.
The problem is that the form fields need specific regex validation which worked well when there was only a single input. Now, when fields are dynamically created by javascript, it only validates the first field.

I've googled around but haven't found anything and for now my only idea is to pass regex value from the settings file to javascript and validate it on the user side but I won't be able to use Page.IsValid() then.

So my question is - is it possible to add server side validation to fields dynamically created by javascript, and how?

Thank you!

Fields Create by javascript is of type input type="text" , If you want server side validation, you have to supply runat="server" with the tag — Akshay Joy, May 16 '13 at 06:58
Can U please share the Code which you used for the creation fields — Akshay Joy, May 16 '13 at 06:58

score 1 · Answer 1 · answered May 16 '13 at 09:04

Short answer is – it is probably possible but it’s very difficult and solution would be very brittle and require a lot of maintenance.

In theory you could do this if you can figure out JS code generated by ASP.NET when regular expression validators are used and then reverse engineer it. Main issue here is that new fields are created on client and not on the server side.

If you can update your page so that new textboxes are created dynamically on the server side then all you have to do is create new text box and new validator in OnInit method and this would work.

Here is how it could look like.

protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);

        //set the appropriate conditions for your solution
        if (true)
        {
            //create text box
            TextBox txtNewField = new TextBox();
            txtNewField.ID = "txtNewField";

            //create and initialize validator
            RegularExpressionValidator regexR1 = new RegularExpressionValidator();

            regexR1.ValidationExpression = "set the regex here";
            regexR1.ControlToValidate = txtNewField.ID;
            regexR1.ErrorMessage = "you are doing something wrong";

            //add both of these to page wehre needed. 
            //I assume there is a panel control where you are adding these 
            //but you can customize it more
            pnlFields.Controls.Add(txtNewField);
            pnlFields.Controls.Add(regexR1);
        }
    }

Thanks! I was just looking at how to do this as my research lead to it. I will try this out. — Eliah John, May 16 '13 at 09:18

Akshay Joy · Answer 2 · 2013-05-16T07:38:57.310

0

If you want Server Side validation and Client side valdiation, then you need to Create the Input type="text" as runat ="server"

Example:-

<input type="text" class="alphanum" id="txtName" name="txtName" runat="server" />

Use Jquery to Validate using Regex

$("input.alphanum").bind("keyup", function(e) {
    this.value = this.value.replace(/[^a-zA-Z0-9]/g, '');
});

edited May 16 '13 at 07:38

answered May 16 '13 at 07:03

Akshay Joy

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Thanks for the answer, but how would I add `` fields to the *.ascx.cs* file? This setup also forces me to set the regular expression patter in my *.ascx* file but it calls the field by it's ID which is changed for each of the new fields (As ID needs to be unique and AFAIK .NET wont validate fields with same ID). The IDs are created like this `field1, field2, field3, ... , fieldn` – Eliah John May 16 '13 at 07:12
try the same you can try the same in client side regex, the Problem is :regularexpressionvalidator is only asp:Textboxes, – Akshay Joy May 16 '13 at 07:14
try something like this http://stackoverflow.com/questions/1547669/restricting-text-box-inputs-to-a-given-regexp-using-jquery – Akshay Joy May 16 '13 at 07:17
Well, this is client side only, the validation happens in users browser whereas I would like to achieve the validation being done on the server side. – Eliah John May 16 '13 at 07:18
Regex you can validate in client side, waht is the Other Event you need validate in Server side, Please tell me the Action you need to implement in Server side , so that we can provide you workaround – Akshay Joy May 16 '13 at 07:21

.NET validate dynamically created fields

2 Answers2