Question: I have:

```
<input name="input4" type="text" id="input4" disabled="disabled" class="jsx-3771882255" data-id="0">

```

I want get data of data-id by C#;

```
string s=input4.Attributes["data-id"].ToString(); //(can'tuse this!)

```

Answer: 
You have the disabled attribute set on your text box, this will not get submitted to the server, use the readonly attribute instead of the disabled attribute.
@vuong quang - Can you check my code and implement it's working for me and also I shared my code with a screenshot.

**HTML Code**

Add runat="server"

```
<input type="text" name="name" value="0" data-id="101" runat="server" id="txtvalue" />

```

[HTML Code](https://i.stack.imgur.com/XGGtt.png)

**Code behind**

```
string id = txtvalue.Attributes["data-id"].ToString();

```

**Check below screenshots**

[CS Page Code](https://i.stack.imgur.com/1beuC.png)