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Regular Expression in ASP.NET


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Regular Expression in ASP.NET

ASP.NET provides validation controls to help you check Web form data entries before the data is accepted and saved in the Database. Validation controls can be used to address the following questions.
1. Did the user enter anything?
2. Is the entry the appropriate kind of data (For example, Date of Birth should be a valid Date; Name should be a string etc.)?
3. Is the data within a required range?(For example age cannot be greater than 100 years)
The validation controls check the validity of data entered in associated server controls on the client before the page is posted back to the server. Most validity problems can be caught and corrected by the user without a round-trip to the server.

There are six controls which are available for performing validation. They are

1.       RequiredFieldValidator

2.       CompareValidator

3.       RegularExpressionValidator

4.       RangeValidator

5.       CustomValidator

6.       ValidationSummary

Create a new website project and you have an Empty default.aspx page. In your Solution Explorer double click it and go to its design view. Look for your toolbar on the left hand side of your window. In the Toolbar look for the Validation Section as depicted below

Regular Expression in ASP.NET

1.     RequiredFieldValidator

The RequiredFieldValidator control is used to make an input control a required field. With this control, the validation fails if the input value does not change from its initial value. By default, the initial value is an empty string ("").

Note: Leading and trailing spaces of the input value are removed before validation.

Note: The InitialValue property does not set the default value for the input control. It indicates the value that you do not want the user to enter in the input control.

Properties

Property

Description

BackColor

The background color of the RequiredFieldValidator control

ControlToValidate

The id of the control to validate

Display

The display behavior for the validation control. Legal values are:

  • None (the control is not displayed. Used to show the error message only in the ValidationSummary control)
  • Static (the control displays an error message if validation fails. Space is reserved on the page for the message even if the input passes validation.
  • Dynamic (the control displays an error message if validation fails. Space is not reserved on the page for the message if the input passes validation

EnableClientScript

A Boolean value that specifies whether client-side validation is enabled or not

Enabled

A Boolean value that specifies whether the validation control is enabled or not

ErrorMessage

The text to display in the ValidationSummary control when validation fails. Note: This text will also be displayed in the validation control if the Text property is not set

ForeColor

The foreground color of the control

id

A unique id for the control

InitialValue

Specifies the starting value of the input control. Default value is ""

IsValid

A Boolean value that indicates whether the control specified by ControlToValidate is determined to be valid

runat

Specifies that the control is a server control. Must be set to "server"

Text

ToolTip

The message to display when validation fails

Display for message on mouse over event

Demo

 Drag - Drop Lable, TextBox , Button and  RequiredFieldValidator controls on webpage.

<body>

    <form id="form1" runat="server">

    <div>

        <asp:Label ID="Label1" runat="server" Text="Name"></asp:Label>

        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

        <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" Text="*" ControlToValidate="TextBox1" ToolTip="Provide some value in TextBox" Display="Dynamic"></asp:RequiredFieldValidator>

        <asp:Button ID="Button1" runat="server" Text="Button" />

    </div>

    </form>

</body>

 

Regular Expression in ASP.NET

When we try click on Button ‘Click’ without enter any string than ‘RequiredFieldValidator’ fire

Regular Expression in ASP.NET

2.     CompareValidator

 

The CompareValidator control is used to compare the value of one input control to the value of another input control or to a fixed value. For example compare email id or password.

Properties

Property

Description

BackColor

The background color of the CompareValidator control

ControlToCompare

The name of the control to compare with

ControlToValidate

The id of the control to validate

Display

The display behavior for the validation control. Legal values are:

  • None (the control is not displayed. Used to show the error message only in the ValidationSummary control)
  • Static (the control displays an error message if validation fails. Space is reserved on the page for the message even if the input passes validation.
  • Dynamic (the control displays an error message if validation fails. Space is not reserved on the page for the message if the input passes validation

EnableClientScript

A Boolean value that specifies whether client-side validation is enabled or not

Enabled

A Boolean value that specifies whether the validation control is enabled or not

ErrorMessage

The text to display in the ValidationSummary control when validation fails. Note: This text will also be displayed in the validation control if the Text property is not set

ForeColor

The foreground color of the control

id

A unique id for the control

IsValid

A Boolean value that indicates whether the control specified by ControlToValidate is determined to be valid

Operator

The type of comparison to perform. The operators are:

  • Equal
  • GreaterThan
  • GreaterThanEqual
  • LessThan
  • LessThanEqual
  • NotEqual
  • DataTypeCheck

runat

Specifies that the control is a server control. Must be set to "server"

Text

The message to display when validation fails

Type

Specifies the data type of the values to compare. The types are:

  • Currency
  • Date
  • Double
  • Integer
  • String

ValueToCompare

ToolTip

A specified value to compare with

Display for message on mouse over event

Demo

Drag - Drop Lable, TextBox , Button and  CompareValidator controls on webpage.

<body>

    <form id="form1" runat="server">

    <div>

        <table>

        <tr>

            <td><asp:Label ID="Label1" runat="server" Text="Password"></asp:Label></td>

            <td><asp:TextBox ID="TextBox1" runat="server" TextMode="Password"></asp:TextBox></td>

        </tr>

        <tr>

            <td><asp:Label ID="Label2" runat="server" Text="Re-password"></asp:Label></td>

            <td><asp:TextBox ID="TextBox2" runat="server" TextMode="Password"></asp:TextBox>

                <asp:CompareValidator ID="CompareValidator1" runat="server" Text="*" Display="Dynamic"

                     ControlToCompare="TextBox1" ControlToValidate="TextBox2" ToolTip="Password not match"></asp:CompareValidator>

            </td>

        </tr>

        <tr><td></td><td><asp:Button ID="Button1" runat="server" Text="Click" /></td></tr>

        </table>

    </div>

    </form>

</body>

 

Regular Expression in ASP.NET

If we inter different – different values in TextBoxes “Password” and “Re-password” than CompareValidator fire

Regular Expression in ASP.NET

 

3.     RangeValidator

The RangeValidator control is used to check that the user enters an input value that falls between two values. It is possible to check ranges within numbers, dates, and characters.

Properties

Property

Description

BackColor

The background color of the RangeValidator control

ControlToValidate

The id of the control to validate

Display

The display behavior for the validation control. Legal values are:

  • None (the control is not displayed. Used to show the error message only in the ValidationSummary control)
  • Static (the control displays an error message if validation fails. Space is reserved on the page for the message even if the input passes validation.
  • Dynamic (the control displays an error message if validation fails. Space is not reserved on the page for the message if the input passes validation

EnableClientScript

A Boolean value that specifies whether client-side validation is enabled or not

Enabled

A Boolean value that specifies whether the validation control is enabled or not

ErrorMessage

The text to display in the ValidationSummary control when validation fails. Note: This text will also be displayed in the validation control if the Text property is not set

ForeColor

The foreground color of the control

id

A unique id for the control

IsValid

A Boolean value that indicates whether the control specified by ControlToValidate is determined to be valid

MaximumValue

Specifies the maximum value of the input control

MinimumValue

Specifies the minimum value of the input control

runat

Specifies that the control is a server control. Must be set to "server"

Type

Specifies the data type of the value to check. The types are:

  • Currency
  • Date
  • Double
  • Integer
  • String

Text

The message to display when validation fails

Demo

Drag - Drop Lable, TextBox , Button and  RangeValidator controls on webpage.

<body>

    <form id="form1" runat="server">

    <div>

        <table>

        <tr>

            <td><asp:Label ID="Label1" runat="server" Text="Age"></asp:Label></td>

            <td><asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

                <asp:RangeValidator ID="RangeValidator1" runat="server" Display="Dynamic" ControlToValidate="TextBox1"

            MinimumValue="18" MaximumValue="28" Type="Integer" Text="age between 18-28 years"></asp:RangeValidator>

            </td>

        </tr>

        <tr>

            <td><asp:Label ID="Label2" runat="server" Text="DOB"></asp:Label></td>

            <td><asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>

                <asp:Label ID="Label3" runat="server" Text="dd/mm/yyyy"></asp:Label>

                <asp:RangeValidator ID="RangeValidator2" runat="server" Display="Dynamic" ControlToValidate="TextBox2"

            MinimumValue="01/07/1984" MaximumValue="01/07/1994" Type="Date" Text="date between 01/07/1984 to 01/07/1994"></asp:RangeValidator>

            </td>      

        </tr>

        <tr>

            <td><asp:Label ID="Label4" runat="server" Text="Currency"></asp:Label></td>

            <td><asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>

                <asp:RangeValidator ID="RangeValidator3" runat="server" Display="Dynamic" ControlToValidate="TextBox3"

            MinimumValue="0.00" MaximumValue="9999999.00" Type="Currency" Text="e.g. 10000.00 or 100000"></asp:RangeValidator>

            </td>      

        </tr>

        <tr>

        <td></td><td> <asp:Button ID="Button1" runat="server" Text="Click" /></td>

        </tr>

        </table>

    </div>

    </form>

</body>

 

Regular Expression in ASP.NET

If we inter wrong input in textboxes then RangeValidator display error message.

Regular Expression in ASP.NET

Right inputs

Regular Expression in ASP.NET

4.     RegularExpressionValidator

The RegularExpressionValidator control is used to ensure that an input value matches a specified pattern.

Note: Both server- and client-side validation are performed unless the browser does not support client-side validation or the EnableClientScript property is set to false.

Properties

Property

Description

BackColor

The background color of the RegularExpressionValidator control

ControlToValidate

The id of the control to validate

Display

The display behavior for the validation control. Legal values are:

  • None (the control is not displayed. Used to show the error message only in the ValidationSummary control)
  • Static (the control displays an error message if validation fails. Space is reserved on the page for the message even if the input passes validation.
  • Dynamic (the control displays an error message if validation fails. Space is not reserved on the page for the message if the input passes validation

EnableClientScript

A Boolean value that specifies whether client-side validation is enabled or not

Enabled

A Boolean value that specifies whether the validation control is enabled or not

ErrorMessage

The text to display in the ValidationSummary control when validation fails. Note: This text will also be displayed in the validation control if the Text property is not set

ForeColor

The foreground color of the control

id

A unique id for the control

IsValid

A Boolean value that indicates whether the control specified by ControlToValidate is determined to be valid

runat

Specifies that the control is a server control. Must be set to "server"

BackColor

The background color of the RegularExpressionValidator control

Text

The message to display when validation fails

ValidationExpression

Specifies the expression used to validate input control. The expression validation syntax is different on the client than on the server. JScript is used on the client. On the server, the language you have specified is used

Demo

Drag – Drop TextBox and RegularExpressionValidator controls on webpage.

<body>

    <form id="form1" runat="server">

    <div>

        <table>

        <tr>

            <td>Name</td><td>

                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"

                    Display="Dynamic" ValidationExpression="^[a-zA-Z''-'\s]{1,40}$"

                    ControlToValidate="TextBox1" ErrorMessage="only alphabets e.g. xyz"></asp:RegularExpressionValidator>

                </td>

            </tr>

            <tr>

            <td>Contact No.</td><td>

                <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator3" runat="server"

                    Display="Dynamic" ValidationExpression="((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}"

                    ControlToValidate="TextBox3" ErrorMessage="e.g. (555) 123-1234 "></asp:RegularExpressionValidator>

                </td>

            </tr>

            <tr>

            <td>Email Id</td><td>

                <asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator4" runat="server"

                    Display="Dynamic"

                   

                    ValidationExpression="^([0-9a-zA-Z]([-\.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$"

                    ControlToValidate="TextBox4" ErrorMessage="e.g. xyz@gmail.com"></asp:RegularExpressionValidator>

                </td>

            </tr>

             <tr>

            <td>Password</td><td>

                <asp:TextBox ID="TextBox5" runat="server" TextMode="Password"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator5" runat="server"

                    Display="Dynamic"

                   

                    ValidationExpression="^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[!@#$%&?]).{4,8}$"

                    ControlToValidate="TextBox5" ErrorMessage="strong password e.g. Abc1#xyz (length 4-8)"></asp:RegularExpressionValidator>

                </td>

            </tr>

        </table>

    </div>

    </form>

</body>

Regular Expression in ASP.NET

Notes- Here I used RegularExpressionValidator for-

Name: - Validates a name.  Allows up to 40 uppercase and lowercase characters and a few special characters that are common to some names.

Contact No.:- Validates us contact number.

Email Id: - Validates an e-mail address.

Password: - Validates a strong password. Passwords will contain at least (1) upper case letter, at least (1) lower case letter, at least (1) number and (1) special character and at least (4-8) characters.

If we inter wrong input in textboxes then RegularExpressionValidator display error message.

Regular Expression in ASP.NET

With right inputs

Regular Expression in ASP.NET

5.     CustomValidator

The CustomValidator control allows you to write a method to handle the validation of the value entered.

Properties

Property

Description

BackColor

The background color of the CustomValidator control

ClientValidationFunction

Specifies the name of the client-side validation script function to be executed. Note: The script must be in a language that the browser supports, such as VBScript or JScript

With VBScript, the function must be in the form:

Sub FunctionName (source, arguments)

With JScript, the function must be in the form:

Function FunctionName (source, arguments)

ControlToValidate

The id of the control to validate

Display

The display behavior for the validation control. Legal values are:

  • None (the control is not displayed. Used to show the error message only in the ValidationSummary control)
  • Static (the control displays an error message if validation fails. Space is reserved on the page for the message even if the input passes validation.
  • Dynamic (the control displays an error message if validation fails. Space is not reserved on the page for the message if the input passes validation

EnableClientScript

A Boolean value that specifies whether client-side validation is enabled or not

Enabled

A Boolean value that specifies whether the validation control is enabled or not

ErrorMessage

The text to display in the ValidationSummary control when validation fails. Note: This text will also be displayed in the validation control if the Text property is not set

ForeColor

The foreground color of the control

id

A unique id for the control

IsValid

A Boolean value that indicates whether the control specified by ControlToValidate is determined to be valid

OnServerValidate

Specifies the name of the server-side validation script function to be executed

runat

Specifies that the control is a server control. Must be set to "server"

Text

The message to display when validation fails

Demo

Drag - Drop TextBox, Button and CustomValidator controls on webpage.

<body>

    <form id="form1" runat="server">

    <div>

    Enter Value

        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

        <asp:Button ID="Button1" runat="server" Text="Button" />

        <asp:CustomValidator ID="CustomValidator1" runat="server" Text=""

            ControlToValidate="TextBox1" onservervalidate="CustomValidator1_ServerValidate" errormessage="The text must be exactly 8 characters long!"></asp:CustomValidator>

       

    </div>

    </form>

</body>

 

Regular Expression in ASP.NET

Note: - In this example, we will simply check the length of the string in the TextBox.

Regular Expression in ASP.NET

6.     ValidationSummary

The ValidationSummary control is used to display a summary of all validation errors occurred in a Web page.

The error message displayed in this control is specified by the ErrorMessage property of each validation control. If the ErrorMessage property of the validation control is not set, no error message is displayed for that validation control.

Properties

Property

Description

DisplayMode

How to display the summary. Legal values are:

  • BulletList
  • List
  • SingleParagraph

EnableClientScript

A Boolean value that specifies whether client-side validation is enabled or not

Enabled

A Boolean value that specifies whether the validation control is enabled or not

ForeColor

The fore color of the control

HeaderText

A header in the ValidationSummary control

id

A unique id for the control

runat

Specifies that the control is a server control. Must be set to "server"

ShowMessageBox

A Boolean value that specifies whether the summary should be displayed in a message box or not

ShowSummary

A Boolean value that specifies whether the ValidationSummary control should be displayed or hidden

Demo

Drag – Drop TextBox , Button and  ValidationSummary controls on webpage.

<body>

    <form id="form1" runat="server">

    <div>

        <table>

        <tr>

            <td>Name</td><td>

                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"

                    Display="Dynamic" ValidationExpression="^[a-zA-Z''-'\s]{1,40}$"

                    ControlToValidate="TextBox1" ErrorMessage="Name accept only alphabets e.g. xyz">*</asp:RegularExpressionValidator>

                </td>

            </tr>

            <tr>

            <td>Contact No.</td><td>

                <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator3" runat="server"

                    Display="Dynamic" ValidationExpression="((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}"

                    ControlToValidate="TextBox3" ErrorMessage="Contact No. as (555) 123-1234 ">*</asp:RegularExpressionValidator>

                </td>

            </tr>

            <tr>

            <td>Email Id</td><td>

                <asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator4" runat="server"

                    Display="Dynamic"

                   

                    ValidationExpression="^([0-9a-zA-Z]([-\.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$"

                    ControlToValidate="TextBox4" ErrorMessage="Email id as xyz@gmail.com">*</asp:RegularExpressionValidator>

                </td>

            </tr>

             <tr>

            <td>Password</td><td>

                <asp:TextBox ID="TextBox5" runat="server" TextMode="Password"></asp:TextBox>

                <asp:RegularExpressionValidator ID="RegularExpressionValidator5" runat="server"

                    Display="Dynamic"

                   

                    ValidationExpression="^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[!@#$%&?]).{4,8}$"

                    ControlToValidate="TextBox5" ErrorMessage="Strong password as Abc1#xyz (length 4-8)">*</asp:RegularExpressionValidator>

                </td>

            </tr>

            <tr>

            <td></td><td>

                <asp:Button ID="Button1" runat="server" Text="Submit" /></td>

                </tr>

        </table>

    </div>

    <asp:ValidationSummary ID="ValidationSummary1" runat="server" />

    </form>

</body>

 

Regular Expression in ASP.NET

Enter wrong inputs and press button ‘Submit’ then ValidationSummary error message display.

Regular Expression in ASP.NET


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