validation controls asp .net

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VALIDATION CONTROLS IN .NET

ARJUN S RArjun.sr007@gmail.comwww.facebook.com/

arjun.aryavarthamtwitter.com/arjun.sr007in.linkedin.com/in/arjun.sr0079745649882

• A validation control (or validator) determines whether the data in another web control is in the proper format, before the data is processed.

• When the XHTML for our page is created, the validator is converted into JavaScript that performs the validation

• JavaScript is a scripting language that enhances the functionality and appearance of web pages and is typically executed on the client.

• Because some clients disable or do not support scripting, ASP.NET validation controls can function on the client,on the server or both.

WHAT VALIDATION CONTROLS DO?

• Rich, declarative validation• Validation declared separately from input control• Extensible validation framework• Supports validation on client and server• Server-side validation is always done– Prevents users from spoofing Web Forms

• Validate User inputs75% of code for handling exceptionsSimplify task

SIX VALIDATION CONTROLS

1. RequiredFieldValidatorEnsures that a value is entered• <asp: RequiredFieldValidator

2. CompareValidator– Compares input to: data type, constant, another control,

database value, etc– <asp: CompareValidator>

3. RangeValidator– Entry within a specified data range– <asp: RangeValidator>

4. ValidationSummary– Summarizes all errors on page– <asp: ValidationSummary>

4. RegularExpressionValidator– Check format against a specific pattern– E-mail address, phone number, zip code, etc– <asp: RegularExpressionValidator>

5. CustomValidator– Write own code– Server- or client-side – <asp: CustomValidator>

• Validation controls are derived from System.Web.UI.WebControls.BaseValidator, which is derived from the Label control

• Validation controls contain text which is displayed only if validation fails• Text property is displayed at control location• ErrorMessage is displayed in summary• Page.IsValid indicates if all validation controls on the page succeed

void Submit_click(object s, EventArgs e) { if (Page.IsValid) { Message. Text = "Page is valid!"; } }

RequiredFieldValidator

<asp: RequiredFieldValidator id=”reqFirstName” ControlToValidate=”txtFirstName” Text=”(Required)” SetFocusOnError=”true” Runat=”server” />

CompareValidator

<asp: CompareValidator id=”cmpBirthDate” Text=”(Invalid Date)” ControlToValidate=”txtBirthDate” Type=”Date” Operator=”DataTypeCheck” Runat=”server” />

RangeValidator

<asp: RangeValidator id=”reqAge” ControlToValidate=”txtAge” Text=”(Invalid Age)” MinimumValue=”5” MaximumValue=”100”

Type=”Integer” Runat=”server” />

ValidationSummary

<asp: ValidationSummary id=”ValidationSummary1” ShowMessageBox=”true” ShowSummary=”false” Runat=”server” />

RegularExpressionValidator

• <asp: RegularExpressionValidator id=”regEmail” ControlToValidate=”txtEmail” Text=”(Invalid email)” ValidationExpression=”\w+([-+.’]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*” Runat=”server” />

CustomValidator

• <asp: CustomValidator id=”valComments” ControlToValidate=”txtComments”

Text=”(Comments must be less than 10 characters)” OnServerValidate=”valComments_ServerValidate” Runat=”server” />

BENEFITS AND LIMITATIONS

Benefits– Convenience

• Cut & paste– Bomb-proof

• Server-side validation

Limitations– Must remember to check on server

• Page.IsValid statement– Different interpretations of regular expressions

• JavaScript vs. server• minor issue

SUMMARY

• Easy to use• Flexible– Validate any type of input

• Combines client- and server-side validation in one control

• Bomb-proof server-side validation

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