I'm really bad with regex and was looking at another question almost identical to this but can't get it to work as I need.
I was to use a RegularExpressionValidator that will allow any character up to 255 characters or nothing at all. I tried,
ValidateExpression="^.{255}$"
but it throws an unhanded exception when the textbox that I'm checking is empty.
I've also tried
ValidateExpression="^.{,255}$"
Thank you
Rodney
Did you try ^.{0,255}$? Not sure what exception you are getting though.
EDIT: Also, if struggling with .Net regex, Regex Hero tester is a great help. I know there are other sites, but this one is by far the best, if you ask me.
The proper expression is ^.{0,255}$.
^.{255}$ will only match if there is exactly 255 characters, while ^.{,255}$ will match the literal string "{,255}".
If there are still issues after trying that, can you tell us the exception?
If it throws an HttpRequestValidationException exception, you can use the members of the UnvalidatedRequestValues class.
Mind that "Validation succeeds if the input control is empty" (MSDN). You may add a RequiredFieldValidator field to ensure that the user does not leave a text box blank (if you use the RequiredFieldValidator control inside an UpdatePanel control, make sure that the validator control and the control it is associated with are in the same panel - MSDN):
<asp:textbox id="myTB"
runat="Server">
</asp:textbox>
// ... MAKE SURE YOU DO NOT USE TextMode="Number"!!!
<asp:RequiredFieldValidator
ID="Value1RequiredValidator"
ControlToValidate="myTB"
ErrorMessage="Please enter a number.<br />"
Display="Dynamic"
runat="server"/>
And as for regex, ^.{255}$ means match any character (except newline) exactly 255 times between string start and end. I think it makes sense to allow ^[1-9][0-9]{0,254}$ (for values like '34', '104', etc.).
Related
I have a text box where a user enters their email address. I need to prevent people using certain email addresses, as this is for corporate (B2B) use.
Can anyone help me with the RegEx which would return false if email addresses contain #gmail or #yahoo?
So far I have this (thanks to #Sabuj) #(yahoo|gmail)\. but when placed into a RegularExpressionValidator it doesn't work:
<asp:RegularExpressionValidator ValidationExpression='#(yahoo|gmail)\.' runat="server" ControlToValidate="txt_email" />
Having read MSDN for more info, I've also tried this but it still returns true regardless of the content entered:
<asp:RegularExpressionValidator ValidationExpression='^(#(yahoo|gmail)\.)$' runat="server" ControlToValidate="txt_email" />
Since e-mail addresses have a complex syntax (more complex than most people realise, for instance, they can contain comments [RFC 822 ยง 3.4.3]), I'd suggest not using regex at all for this. Instead, use a "proper" e-mail parser, then ask the parser for the domain part of the address.
Use this:
<asp:RegularExpressionValidator ValidationExpression=".*#(?!(yahoo|gmail)).*" ControlToValidate="txt_email" runat="server" ErrorMessage="Yahoo and Gmail disallowed"></asp:RegularExpressionValidator>
The validation expression property should be set to match the entire string.
But my regex .*#(?!(yahoo|gmail)).* matches the whole email. So it works :)
You don't need ^ or $ since the string is gonna be a single line.
Also don't forget to add type="email" to your txt_email. It will automatically take care of whether it is a valid email or not.
If the error msg appears, then it isn't valid, but if it doesn't appear, then it is absolutely valid.
I've come up with ^.*#(?!(yahoo|gmail)).*$
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" ValidationExpression="^.*#(?!(yahoo|gmail)).*$" runat="server" ControlToValidate="txt_email" Text="No free email accounts allowed" />
This will allow any text to pass the validator that doesn't contain #yahoo or #gmail.
Don't forget to check Page.IsValid in your code behind, and to include an <asp:ValidationSummary runat="server" /> in your .aspx.
You can use this regex to check whether the mentioned emails are containing or not:
#(gmail|yahoo|mailinator|guerrillamail|dispostable)\.
I have a form in which I would like guests to enter their name, address etc...
On each field I have a RequiredFieldValidator and a RegularExpressionValidator.
For example:
<asp:TextBox ID="mailNameTextBox" runat="server" MaxLength="70" ValidationGroup="mail"></asp:TextBox>
<asp:RegularExpressionValidator ID="mailNameTextBox_RegularExpressionValidator" runat="server" ErrorMessage="Name can only have letters or spaces." ControlToValidate="mailNameTextBox" ValidationExpression="[a-zA-Z' ']" ValidationGroup="mail" Display="Dynamic">*</asp:RegularExpressionValidator>
<asp:RequiredFieldValidator ID="mailNameTextBox_RequiredFieldValidator" runat="server" ErrorMessage="Name field is required." ControlToValidate="mailNameTextBox" ValidationGroup="mail" Display="Dynamic">*</asp:RequiredFieldValidator>
When I enter a name that includes a number (ie. fails the Regex) and "tab" out of the TextBox, the RegexValidator is instantly displayed with a *, and the form fails to submit. But when I go back and remove the number (ie. pass the Regex), the Validator doesn't seem to re-check the input, and the form will forever fail to submit.
Is there a way to always fire the Validation when leaving the box rather than just the first time (besides calling a Validation method upon the TextBox losing focus). I would have thought this would be automatic?
I have spent some time trying to find an answer to this, and I'm not sure how to word my question to "thouroughly research it", so I'm sorry if this is a duplicate.
I did see this one:
ASP.NET: RegularExpressionValidator Doesn't reCheck the input
but it didn't really help in my case.
Your validation expression is this:
[a-zA-Z' ']
Which means: exactly one letter or one apostroph or one space.
You probably want to use something like the following:
[\w\s]*
Which means: any number of letters or whitespaces.
Sorry for the Dummy Question , i know :( ,, but it's only the simple things that dont work with me :((
i have many text boxes and i want the user to only insert String and not Numeric numbers ,
how could i handle it in easy way ??
as it takes every thing and apply it to the database , or should i control it from the Database
PS. i have searched a lot but with no good answer
use [a-zA-Z]+ for ValidationExpression:
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"
ControlToValidate="TextBox1" ErrorMessage="RegularExpressionValidator"
ValidationExpression="[a-zA-Z]+"></asp:RegularExpressionValidator>
You could take a look at validation techniques for asp : http://msdn.microsoft.com/en-us/library/7kh55542.aspx
This provide a set of tools to check whether the input match what you expect.
You can do it easily in AJAX,just download it from here
first add a script manager to your page then add FilteredTextBoxExtender to the textbox and set it's properties as you wish.
A Regular Expression could be applied to the input
For the basics on RegEx : http://www.regular-expressions.info/tutorial.html
And also see
http://www.regular-expressions.info/dotnet.html
You can use regex to do that with jQuery.
In this example, I replace only digits.
You can adapt the regex to replace any set of characters with an empty string.
Following expression work well for email validation with asp.net but does not allow whitespace at start and end.
^(([a-zA-Z0-9_\-\.]+)#([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+([;.](([a-zA-Z0-9_\-\.]+)#([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+)*$
Have any way to allow whitespace?
Here is full asp.net markup, I can not trim before validation.
<asp:TextBox ID="txtEmail" runat="server" MaxLength="100" CssClass="textbg text"></asp:TextBox>
<asp:RegularExpressionValidator ID="EmailValidator" runat="server" ErrorMessage="Email is not vaild."
ForeColor="Red" ControlToValidate="txtEmail" ValidationExpression="^(([a-zA-Z0-9_\-\.]+)#([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+([;.](([a-zA-Z0-9_\-\.]+)#([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+)*$"
ValidationGroup="register">Email is not vaild.</asp:RegularExpressionValidator>
I would echo the previous points suggesting trimming the input prior to validation. Trimming or ignoring whitespace is a pretty common requirement, so I would be very surprised if your validator couldn't handle it.
I would also point out an email address with that spaces on either end is an invalid email address, so passing it as valid is technically incorrect.
However, if it can't trim it, and you must pass it, then it is trivially easy to modify any regex to allow whitespace at either end.
White space is represented in regex with \s. Zero or more white spaces would be \s*.
Therefore, all you need to do is add \s* to the start and end of the expression, immediately inside the^and$` start and end markers, like so:
/^\s*(.......)\s*$/
(where ...... represents an expression to validate an email address (but probably not the one you've quoted in the question).
Hope that helps.
Email validation using regular expressions are not easy. Since you're using ASP.NET, you could just use the same regular expression MailAddress uses. Presumably most email addresses are not going to be invalid, so the Try...Catch operation shouldn't be too expensive.
MailAddress mailAddress;
try
{
mailAddress = new MailAddress(txtEmail.Text);
}
catch (Exception ex)
{
//Email considered invalid
}
Edit 2 - This one should work with the validator:
(\s?)+\w+(([a-zA-Z0-9_\-\.]+)#([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+([;.](([a-zA-Z0-9_\-\.]+)#([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+)*(\s?)+
Just be aware, email validation cannot be considered reliable because it's very easy to bypass most of the regular expressions.
I have a textbox where the user must not be able to enter more than two digits after a decimal.How do I do this without using javascript?
Thanks.
You can set the MaxLength property of the textbox, but that doesn't have any notion of whether or where the decimal point is.
You could also use a CustomValidator and check the inputted number on the server via the ServerValidate event. But this will require going to the server to check the value (i.e. it will initially look like your form allows users to input invalid numbers).
You should also be able use to a RegularExpressionValidator, depending on your exact globalization requirements, which will use JavaScript on the client to provide immediate feedback:
<asp:TextBox ID="NumberTextBox" runat="server" />
<asp:RegularExpressionValidator runat="server" ControlToValidate="NumberTextBox"
ValidationExpression="\d+(?:(?:\.|,)\d{1,2})?" />
If you want the immediate feedback to the user, you'll need to use a JavaScript based solution.
You cannot cause the textbox to stop accepting text after two decimal places without directly or indirectly using javascript. (This is sometimes called an input mask).
You can, however, allow the user to enter free-form text and validate the text upon postback on the server. You can either automatically round the number for them, or return an error message to the client.
If you really need to prevent the user from entering more than two digits after the decimal point, you'll need to use JavaScript or a server control that implements the JavaScript for you.
However, may make more sense to allow them to enter any number of digits and then catch it on validation (or just round to two digits).