Validation Controls

1
Validation Controls
2
Outline

• Review of web controls
• Use validation controls to implement validations
  for a web page
• Describe the use of the IsValid property of a
  page and the Validate method of a page

3
Page.IsPostBack

• Page default object
• Belongs to web page class
• IsPostBack
• A property of the web page class
• Boolean variable
• False when the page is displayed the first time
• True the page is being redisplayed in response
  to a control event

4
Web.config

• Upload and store the file at your folder on the
  server
• It can control error message display
• The following web.config will allow error
  messages to be displayed
• lt!-- Web.Config Configuration File --gt
• ltconfigurationgt
• ltsystem.webgt
• ltcustomErrors mode"Off"/gt
• lt/system.webgt
• lt/configurationgt

5
Validation Controls in ASP.NET

• RequiredFieldValidator
• CompareValidator
• RangeValidator
• RegularExpressionValidator

6
Common Properties of Validation Control

• ControlToValidate The control the validator will
  check.
• ErrorMessage The text message when validation
  fails.
• IsValid It returns True or False depending on
  whether the validation succeeded or failed.

7
Required Field Validator

• ltaspTextBox ID"txtName" runat"server"gtlt/aspTex
  tBoxgt
• ltaspRequiredFieldValidator ID"RequiredFieldValid
  ator1"
• runat"server"
• ControlToValidate"txtName"
• ErrorMessage"You must enter a name."gt
• lt/aspRequiredFieldValidatorgt

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Additional Properties of the Compare Validator
9
A compare validator that checks for a value
greater than zero

• ltaspTextBox ID"txtQuantity" runat"server"gt
• lt/aspTextBoxgtnbsp
• ltaspCompareValidator ID"CompareValidator1"
• runat"server"
• ControlToValidate"txtQuantity"
  Type"Integer"
• Operator"GreaterThan" ValueToCompare"0"
• ErrorMessage"Quantity must be greater than
  zero."gt
• lt/aspCompareValidatorgt

10
Compare Two Textboxes

• ltaspTextBox ID"txtStartDate" runat"server"gtlt/as
  pTextBoxgtltbr /gt
• ltaspTextBox ID"txtEndDate" runat"server"gt
• lt/aspTextBoxgt
• ltaspCompareValidator
• ID"CompareValidator3" runat"server"
• ControlToValidate"txtEndDate"
• Operator"GreaterThan" Type"Date"
• ControlToCompare"txtStartDate"
• ErrorMessage
• "End Date must be greater than Start
  Date."gt
• lt/aspCompareValidatorgt

11
Additional Properties of the Range Validator
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A range validator that checks for a numeric range

• ltaspTextBox ID"txtDays" runat"server"gtlt/aspTex
  tBoxgt
• ltaspRangeValidator ID"RangeValidator1"
  runat"server"
• ControlToValidate"txtDays" Type"Integer"
• MinimumValue"1" MaximumValue"14"
• ErrorMessage"Days must be between 1 and
  14."gt
• lt/aspRangeValidatorgt

13
Regular Expression

• In computing, a regular expression, also called a
  pattern, is an expression that describes a set of
  strings
• It provide a concise and flexible way to identify
  strings of text
• Regular expressions can be used with regular
  expression validator to check whether the input
  data match a particular pattern

14
Common Regular Expression Items

• \ Matches the character that follows.
• \d Matches any decimal digit (0-9)
• \w Matches any word character including letters,
  numbers, and underscore (a-z, A-Z, and 0-9).
• \S Matches non-whitespace character
• n Matches exactly n occurrences of the
  preceding element or group.
• n, Matches at least n occurrences of the
  preceding element or group.
• n,m Matches at least n but no more than m
  occurrences of the preceding element or group.

15
Common Regular Expression Items

• abcd Matches any character included between the
  brackets.
• abcd Matches any character that is not
  included between the brackets.
• a-z Matches any characters in the indicated
  range.
• Matches zero or more occurrences of the
  preceding element.
• ? 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 to be treated as a single element.
  For example, (78) matches 78 and 787878

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Examples

• \d3 Three numbers
• \w4,10 A password that must be between 4 to 10
  characters
• \S4,10 A password that must be between 4 to 10
  characters, allowing special characters
  including asterisks, ampersands, etc.
• \S_at_\S\.\S Check for an _at_ sign and dot (.) and
  allow non-whitespace characters

17
IsValid Property

• Validation control
• this property depends on whether the validation
  was successful
• Page
• this property to indicate whether all the input
  data is valid