Multiple controls with the same ID

Question

Multiple controls with the same ID 'xxxx' were found. FindControl requires that controls have unique IDs.

I want to bypass this validation. I want to have same id's for multiple elements. I am creating dynamic controls and my css class is applied based on id and class combinations. Everything works when the page loads for the first time, but on page postback I get this error.

Can I do anything to bypass this validation?

Answer 1

You cannot have several elements with the same Server ID inside a common NamingContainer.
If you really want to have the same Server ID, put your controls inside separate NamingContainer (RepeaterItem?).

Now if you need the same Html/DOM ID, you can't have that.
Use something else than the Id to distinct your elements from a CSS point of view.
You could use partially matching ID though...

*[id*="_MyButtonID"].red {
    background-color: red;
}

Answer 2

In HTML, you cannot have multiple elements with the same ID. Sounds more logical that you rewrite your CSS to not be based on ID.

Answer 3

You can't, ASP requires unique IDs. Otherwise how will know which control to reference in the code?

E.g

string x = NameBox.Text;

Well which one would you use if you had 20 of those, all with different content?

I would suggest you rewrite your CSS to not be based on IDs, maybe follow Harry Roberts way of Hashed Classes?

Answer 4

Why don't use you give your controls multiple classes instead of relying on the IDs? Trying to use controls with the same IDs really isn't going to work.

For example:

<asp:TextBox id="textFirstName" runat="server" CssClass="name firstname" />
<asp:TextBox id="textLastName" runat="server" CssClass="name lastname" />

In your CSS you can then use selectors such as .name.firstname to select elements with BOTH the name and firstname class

Note - there's no space between the class names .name.firstname.