In an ASP.NET Listview, I need to raise an error with a RegularExpressionValidator control if a string in an textbox control exceeds a given length. I have minimal experience with regular expressions and hopefully someone can tell me if this is a good use of regular expressions and help me get started with the expression. Thanks.
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3 Answers
You don't need validator to do that. Just set TextBox.MaxLength property to your desired length.
Gets or sets the maximum number of characters allowed in the text box.
1 Comment
Bicycle Dave
Thank you very much - exactly what I needed even if I feel pretty dumb for missing such a simple solution. Live and Learn! Thanks again.
As you said, use a Regular Expression Validator and set the expression to something like this:
^([\S\s]{0,10})$
Replace the 4 with your desired max lenght.
Update:
<asp:TextBox id="wtxtTPP" Runat="server" />
<asp:RegularExpressionValidator id="RegularExpressionValidator1" runat="server"
ErrorMessage="RegularExpressionValidator"
ValidationExpression="^([\S\s]{0,0})$"
ControlToValidate="wtxtTPP" />
Or
Use MaxLength Property
like
<asp:TextBox id="wtxtTPP" Runat="server" MaxLength="10"/>
2 Comments
sh1rts
It's worth noting that if someone disables or modifies MaxLength using Firebug (for example), they can submit the form with more than 4 characters in your textbox. You will need the RegularExpressionValidator (or a server-side validation approach) to ensure the value is not greater than 4 characters.
Bicycle Dave
Thanks Vignesh, your RegExp example works perfectly and has the advantage of giving a normal validation error message. Both the these methods together works very well - along with the server side.
Some of the properties of regular expression:
<asp:RegularExpressionValidator
AccessKey="string"
AssociatedControlID="string"
BackColor="color name|#dddddd"
BorderColor="color name|#dddddd"
BorderStyle="NotSet|None|Dotted|Dashed|Solid|Double|Groove|Ridge|
Inset|Outset"
BorderWidth="size"
ControlToValidate="string"
CssClass="string"
Display="None|Static|Dynamic"
EnableClientScript="True|False"
Enabled="True|False"
EnableTheming="True|False"
EnableViewState="True|False"
ErrorMessage="string"
Font-Bold="True|False"
Font-Italic="True|False"
Font-Names="string"
Font-Overline="True|False"
Font-Size="string|Smaller|Larger|XX-Small|X-Small|Small|Medium|
Large|X-Large|XX-Large"
Font-Strikeout="True|False"
Font-Underline="True|False"
ForeColor="color name|#dddddd"
Height="size"
ID="string"
OnDataBinding="DataBinding event handler"
OnDisposed="Disposed event handler"
OnInit="Init event handler"
OnLoad="Load event handler"
OnPreRender="PreRender event handler"
OnUnload="Unload event handler"
runat="server"
SetFocusOnError="True|False"
SkinID="string"
Style="string"
TabIndex="integer"
Text="string"
ToolTip="string"
ValidationExpression="string"
ValidationGroup="string"
Visible="True|False"
Width="size"
/>
You can refer to MSDN docs for RegularExpressionValidator for more detail.
