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Transcript of Module 7: Validating User Input. Overview Overview of User Input Validation Using Validation...
![Page 1: Module 7: Validating User Input. Overview Overview of User Input Validation Using Validation Controls Page Validation.](https://reader035.fdocuments.in/reader035/viewer/2022062300/56649e2a5503460f94b189ae/html5/thumbnails/1.jpg)
Module 7:
Validating User Input
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Overview
Overview of User Input Validation Using Validation Controls Page Validation
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Lesson: Overview of User Input Validation
What Is Input Validation? Client-Side and Server-Side Validation ASP.NET Validation Controls
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What Is Input Validation?
Def : A process of verifying that a user’s input on a web form matches the expected data value, range or format.
Works by comparing user input against a predetermined input format.
Verifies that a control value is correctly entered by the user Blocks the processing of a page until all controls are valid Avoids spoofing
or the addition ofmalicious code
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Client-Side and Server-Side Validation
ASP.NET can create both client-side and server-side validation
Client-side validation • Dependent on browser
version• Instant feedback• Reduces postback cycles• Uses JavaScript and DHTML
Server-side validation• Repeats all client-side
validation• Can validate against stored
data• Server side validation control
Valid?
Valid?
User Enters Data
No
No
Yes
Yes
Error Message
Client
Server
Web ApplicationProcessed
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ASP.NET Validation Controls
ASP.NET provides validation controls to:
Compare values – Compares an input control to another input control. Eg: Password verification fields.(CompareValidator)
Compare to a custom formula – Allows you to write your own code to create the validation expression. ( CustomValidator)
Compare to a range – Verifies that the user input is between two values or the values of other input controls. ( RangeValidator )
Compare to a regular expression pattern – Verifies that the entry matches a pattern that has been defined by a regular expression. ( RegularExpressionValidator )
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ASP.NET Validation Controls Require user input – checks whether a value has been entered
on the control. ( RequiredFieldValidator )
Summarize the validation controls on a page – Display a summary of all of the validation errors on the page. Typically placed naer the Submit button to provide immediate feedback on the page input status. ( ValidationSummary )
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Lesson: Using Validation Controls
Adding Validation Controls to a Web Form Positioning Validation Controls on a Web Form Combining Validation Controls Input Validation Controls Using the RegularExpressionValidator Control Using the CustomValidator Control
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Adding Validation Controls to a Web Form
1. Add a validation control
2. Select the input control to validate
3. Set validation properties
<asp:Type_of_Validator id="Validator_id"runat="server"ControlToValidate="txtName"ErrorMessage="Message_for_error_summary"Display="static|dynamic|none"Text="Text_to_display_by_input_control">
</asp:Type_of_Validator>
<asp:Type_of_Validator id="Validator_id"runat="server"ControlToValidate="txtName"ErrorMessage="Message_for_error_summary"Display="static|dynamic|none"Text="Text_to_display_by_input_control">
</asp:Type_of_Validator>
<asp:TextBox id="txtName" runat="server" /><asp:TextBox id="txtName" runat="server" />
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Positioning Validation Controls on a Web Form
Create error messages Select display mode
•Static:fixed layout for the error page
•DynamicEnables validation controls to render in the page as part of the text flow
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Combining Validation Controls Can have multiple validation controls on a single input control Only the RequiredFieldValidator checks empty controls
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Input Validation Controls RequiredFieldValidator
• InitialValue
CompareValidator• ValueToCompare or ControlToCompare• Type• Operator
RangeValidator• MinimumValue• MaximumValue• Type
Code Examples
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Using the RegularExpressionValidator Control
Used when input must conform to a pre-defined pattern Visual Studio .NET includes patterns for:
• Telephone numbers
• Postal codes
• E-mail addresses
<asp:RegularExpressionValidator …ControlToValidate="US_PhoneNumber"…ValidationExpression="((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4} "…>*</asp:RegularExpressionValidator >
<asp:RegularExpressionValidator …ControlToValidate="US_PhoneNumber"…ValidationExpression="((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4} "…>*</asp:RegularExpressionValidator >
Code Example
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Demonstration: Using Validation Controls
Create an ASP.NET Web Form with TextBox and Button controls
Add a RequiredFieldValidator control Add a RangeValidator control Add a RegularExpressionValidator control
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Using the CustomValidator Control Can validate on client-side, server-side, or both
• ClientValidationFunction
• OnServerValidate Validate with:
• Formula
• Data
• COM objects
• Web Service
Code Example
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Demonstration: Using the CustomValidator Control
Add a CustomValidator control Write the server-side code Write the client-side script Test the result
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Lesson: Page Validation Using the Page.IsValid Property ( Server-side verification ) Using the ValidationSummary Control ( Client-side
verification ) Demonstration: Using the Page.IsValid Property and the
ValidationSummary Control
.NET enables you to verify that all of the controls on a page are valid before the controls perform some action.
The verification of validity can be conducted on either client or server, depending on the browser being used.
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Using the Page.IsValid PropertyPolls all validation controls
Sub cmdSubmit_Click(s As Object, e As EventArgs)If Page.IsValid Then
Message.Text = "Page is valid!"' Perform database updates or other logic
here End If
End Sub
Sub cmdSubmit_Click(s As Object, e As EventArgs)If Page.IsValid Then
Message.Text = "Page is valid!"' Perform database updates or other logic
here End If
End Subprivate void cmdSubmit_Click(object s,
System.EventArgs e){ if (Page.IsValid)
{ Message.Text = "Page is Valid!";// Perform database updates or other logic
here}
}
private void cmdSubmit_Click(object s, System.EventArgs e)
{ if (Page.IsValid){ Message.Text = "Page is Valid!";
// Perform database updates or other logic here}
}
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Using the ValidationSummary Control
Collects error messages from all validation controls on the page Can display text and error messages Use Text="*" to indicate the location of the error
<asp:ValidationSummary id="valSummary"runat="server"HeaderText="These errors were found:"ShowSummary="True" DisplayMode="List"/>
<asp:ValidationSummary id="valSummary"runat="server"HeaderText="These errors were found:"ShowSummary="True" DisplayMode="List"/>
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Review Overview of User Input Validation Using Validation Controls Page Validation
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ExerciseFor the following questions, you will select the type of validation control(s) that should be used for each scenario.The types of validation controls available for a Web Form include:
CompareValidatorCustomValidatorRangeValidatorRegularExpressionValidatorRequiredFieldValidatorValidationSummary
Given the following user input fields, what kind of validation control(s)would you use?1. The user‘s age.
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Exercise (cont.)
2. The user‘s telephone number.
3. The user‘s password, which is entered twice.
4. Whether an entered number is prime.
5. Whether all of the fields in a form are correctly filled in.
6. Whether the date format is correct.
7. Whether a new employee‘s requested e-mail address matches the company policy.
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