get checkbox Controls by custom attribute name in C#

Question

I have a collection of checkbox some 40-50 nos and i have set a attribute 'attr-ID' for each checkbox which is a unique value ID in database. how can i get the control by attribute name in c# code. I want to check some of the checkbox according to dB values on page load event.

 <input type="checkbox" id="rdCervical" attr-ID='111' runat='server' />

Do they have runat="server" attribute or are they simple html elements? — Tomislav Markovski
– Tomislav Markovski, Commented Dec 22, 2011 at 13:54
HTML5 allows attributes that begin with data- but for anything else I think you'll have to write your own parser, I'm afraid. — Bala R
– Bala R, Commented Dec 22, 2011 at 13:55
yea they have runat server but i cannot identifiy the control id in c# — deepu
– deepu, Commented Dec 22, 2011 at 14:00
If they have runat="=server" they should be available in the code behind. are they located maybe in a custom control? Can you post some more code of the containers? — Tomislav Markovski
– Tomislav Markovski, Commented Dec 22, 2011 at 14:05
its a normal html control but i have many checkbox and identifying each checkbox id in server side have to check each id and the attribute value which i dont need. so if there some way to check the attribute and get it checked. — deepu
– deepu, Commented Dec 23, 2011 at 4:04

Arion · Accepted Answer · 2011-12-22 14:42:15Z

6

Is this what you want?

protected void Page_Load(object sender, EventArgs e)
{
    var cb = FindControlByAttribute<HtmlInputCheckBox>(this.Page, "attr-ID", "111");

}
public T FindControlByAttribute<T>(Control ctl, string attributeName, string attributeValue) where T : HtmlControl
{
    foreach (Control c in ctl.Controls)
    {
        if (c.GetType() == typeof(T) && ((T)c).Attributes[attributeName]==attributeValue)
        {
            return (T) c;
        }
        var cb= FindControlByAttribute<T>(c, attributeName, attributeValue);
        if (cb != null)
            return cb;
    }
    return null;
}

edited Dec 22, 2011 at 14:42

answered Dec 22, 2011 at 14:23

Arion

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3 Comments

Tomislav Markovski Over a year ago

He is not using server controls, but html controls HtmlInputCheckBox

deepu Over a year ago

@Arion : can u specify a region in your function means to find a control in a specified div like i have some 50 checkbox in a div which have a id ='dvCheckboxes'. i used your funciton but i am always getting null value. thanks for your post.. and pls help

Arion Over a year ago

@deepu: this function loops all the control on the page. If there is a control with the attribute attr-ID and the value of that is 111 the it will return it. If you have a div with checkboxes see so that it has runat="server". Then you can use that control in this function and it will return the checkbox

carla · Accepted Answer · 2017-11-27 15:08:37Z

5

if (rdCervical.Attributes["attr-ID"] != null)
{
      string id = rdCervical.Attributes["attr-ID"];
      rdCervical.Checked = true;
}

I assume you are adding the checkboxes programatically. In that case, make a container <div id="checkContainer" runat="server"></div> and put all your checkboxes inside it. Then just use checkContainer.InnerHtml and parse that code with this library. You can then easily use the library API to find elements by attribute, I think the method was SelectNodes

Without this library, there is no easy way to navigate through HTML elements from code.

edited Nov 27, 2017 at 15:08

carla

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answered Dec 22, 2011 at 14:04

Tomislav Markovski

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2 Comments

deepu Over a year ago

the checkbox id cannot be checked since i have many checkboxes i have a common attribute for all checkbox using it i need to identify which checkbox is need to be checked

Tomislav Markovski Over a year ago

I assume you are adding the checkboxes programatically. In that case, make a container <div id="checkContainer" runat="server"></div> and put all your checkboxes inside it. Then just use checkContainer.InnerHtml and parse that code with this library. You can then easily use the library API to find elements by attribute. htmlagilitypack.codeplex.com

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