Objectives: • Describe the use of each of the six validation controls provided by ASP.NET. • Describe the use of the ErrorMessage and Text properties of a validation control. • Explain how ASP.NET processes validation controls. • Describe two types of validation that can be done by a required field validator. • Describe three types of validation that can be done by a compare validator. • Describe the use of validation groups. • Describe the use of the IsValid property of a page and the Validate method of a page. • List two common uses for the regular expression validator. • Describe the use of a custom validator.
Chapter 7
How to use the validation controls Spring 2007 Prof. Rasley
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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© 2006, Mike Murach & Associates, Inc.
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Common validator properties
The validation controls provided by ASP.NET Control
Murach’s ASP.NET 2.0/VB, C7
• ControlToValidate
Name RequiredFieldValidator CompareValidator RangeValidator RegularExpressionValidator CustomValidator
• Display • ErrorMessage • Text • Enabled • EnableClientScript • ValidationGroup
ValidationSummary
• IsValid
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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Where is validation performed? Typical code for processing a page that contains validation controls
• On the client if JavaScript is enabled • Also on the server… • This is a security measure so that a fake form is not posted back to the server with invalid data on it • Client-side validation may be disabled by setting the EnableClientScript property to false
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
Protected Sub btnAdd_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles btnAdd.Click If Page.IsValid Then Dim CartItem As New CartItem CartItem.Product = SelectedProduct CartItem.Quantity = CType(txtQuantity.Text, Integer) Me.AddToCart(CartItem) Response.Redirect("Cart.aspx") End If End Sub
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Additional property of the required field validator Property InitialValue
Murach’s ASP.NET 2.0/VB, C7
Description The initial value of the control that’s validated. If this value isn’t changed, the validation fails. The default is an empty string.
© 2006, Mike Murach & Associates, Inc.
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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A required field validator that forces an option to be chosen from a list box --Select a credit card-- Visa MasterCard American Express
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Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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Additional properties of the compare validator
How the input controls are initially displayed in a browser
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
Property ValueToCompare
Description The value that the control specified in the ControlToValidate property should be compared to. Operator The type of comparison to perform (Equal, NotEqual, GreaterThan, GreaterThanEqual, LessThan, LessThanEqual, or DataTypeCheck). Type The data type to use for the comparison (String, Integer, Double, Date, or Currency). ControlToCompare The ID of the control that the value of the control specified in the ControlToValidate property should be compared to.
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Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
Slide 10
A compare validator that checks for a value greater than zero
A compare validator that compares the values of two text boxes
A compare validator that checks for a numeric entry
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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How to set a range at runtime
Additional properties of the range validator Property MinimumValue MaximumValue Type
Description The minimum value allowed for the control. The maximum value allowed for the control. The data type to use for the comparison (String, Integer, Double, Date, or Currency).
A range validator that checks for a numeric range
Murach’s ASP.NET 2.0/VB, C7
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Properties of the validation summary control Property DisplayMode
HeaderText ShowSummary
ShowMessageBox
Murach’s ASP.NET 2.0/VB, C7
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
Slide 14
Two validators and a validation summary control that’s displayed on the web page
Description Specifies how the error messages from the validation controls are to be displayed. The available values are BulletList, List, or SingleParagraph. The default is BulletList. The text that’s displayed before the list of error messages. A Boolean value that determines whether the validation summary should be displayed on the web page. The default is True. A Boolean value that determines whether the validation summary should be displayed in a message box (client-side validation only). The default is False.
© 2006, Mike Murach & Associates, Inc.
A range validator that checks a date range set at runtime 01/01/06 Code that sets the minimum and maximum values when the page is loaded Protected Sub Page_Load(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles Me.Load If Not IsPostBack Then valArrival.MinimumValue = Today.ToShortDateString valArrival.MaximumValue = _ Today.AddDays(30).ToShortDateString End If End Sub
* *
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Murach’s ASP.NET 2.0/VB, C7
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How the controls appear on the web page
Attributes that cause group validation when a button is clicked Attribute CausesValidation ValidationGroup
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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© 2006, Mike Murach & Associates, Inc.
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A regular expression validator that validates U.S. phone numbers
An additional property of the regular expression validator Property ValidationExpression
Murach’s ASP.NET 2.0/VB, C7
Description Specifies whether validation should be performed when the user clicks the button. Specifies the name of the group to be validated if CausesValidation is True.
Description A string that specifies a regular expression. The regular expression defines a pattern that the input data must match to be valid.
A regular expression validator that validates fivedigit numbers
The Regular Expression Editor dialog box
Murach’s ASP.NET 2.0/VB, C7
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Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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Common regular expression elements
Common regular expression elements (continued)
Element Ordinary character
Element [abcd]
\ \d \D \w \W \s \S
Description Matches any character other than ., $, ^, [, {, (, |, ), *, +, ?, or \. Matches the character that follows. Matches any decimal digit (0-9) Matches any character other than a decimal digit. Matches any word character (a-z, A-Z, and 0-9). Matches any character other than a word character. Matches any white space character (space, tab, new line, etc.). Matches any character other than a whitespace character.
[^abcd] [a-z] {n} {n,} {n,m} *
Murach’s ASP.NET 2.0/VB, C7
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Description Matches any character included between the brackets. Matches any character that is not included between the brackets. Matches any characters in the indicated range. Matches exactly n occurrences of the preceding element or group. Matches at least n occurrences of the preceding element or group. Matches at least n but no more than m occurrences of the preceding element or group. Matches zero or more occurrences of the preceding element.
© 2006, Mike Murach & Associates, Inc.
Common regular expression elements (continued)
Examples of regular expressions
Element ?
Expression \d{3} \w{8,20} \d{2}-\d{4} \w{1,8}.\w{1,3} (AB)|(SB)-\d{1,5} \d{5}(-\d{4})? \w*\d\w* [xyz]\d{3}
+ | ( )
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Description Matches zero or one occurrence of the preceding element. Matches one or more occurrences of the preceding element. Matches any of the elements separated by the vertical bar. Groups the elements that appear between the parentheses.
© 2006, Mike Murach & Associates, Inc.
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Murach’s ASP.NET 2.0/VB, C7
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Example 289 Frankenstein 10-3944 freddy.jpg SB-3276 93711-2765 arm01 x023
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Properties of the ServerValidateEventArgs class Property Value IsValid
Description The text string to be validated. A Boolean property that you set to True if the value passes the validation test or to False otherwise.
VB code for a credit card validator Private Sub valCreditCardNumber_ServerValidate( _ ByVal source As Object, _ ByVal args As _ System.Web.UI.WebControls.ServerValidateEventArgs) _ Handles valCreditCardNumber.ServerValidate args.IsValid = ValidateCreditCard(args.Value) End Sub
Aspx code for a text box and a custom validator
Visual Basic code for the custom validator Private Sub valProductCode_ServerValidate( _ ByVal source As Object, _ ByVal args As _ System.Web.UI.WebControls.ServerValidateEventArgs) _ Handles valProductCode.ServerValidate args.IsValid = HalloweenDB.CheckProductCode(args.Value) End Sub Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
Slide 25
VB code for a credit card validator (continued) For i = 0 To CardNumber.Length - 1 If (i + 1) Mod 2 = 0 Then sDigits &= _ CType(CardNumber.Substring(i, 1), Integer) * 2 Else sDigits &= CardNumber.Substring(i, 1) End If Next 'Add the digits For i = 0 To sDigits.Length - 1 iDigitSum += CType(sDigits.Substring(i, 1), Integer) Next 'Check that the sum is divisible by 10 If iDigitSum Mod 10 = 0 Then Return True Else Return False End If End Function
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Slide 27
Private Function ValidateCreditCard( _ ByVal CardNumber As String) As Boolean Dim iDigitSum As Integer Dim sDigits As String = "" Dim i As Integer 'Remove spaces and reverse string CardNumber = _ StrReverse(CardNumber.Replace(" ", Nothing)) 'Double the digits in even-numbered positions
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
Slide 26
What the mod 10 validation algorithm does • Removes any spaces from the number. • Reverses the number. • Doubles the digits in even-numbered positions. If the original digit is 5 or greater, this will insert an additional digit into the number. • Adds up the individual digits. • Divides the result by 10. If the remainder is 0, the credit card number is valid.
Murach’s ASP.NET 2.0/VB, C7
© 2006, Mike Murach & Associates, Inc.
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