Web Development Using ASP 'NET

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Web Development Using ASP .NET
Welcome to week 5-1 of

• CA 240
• Kashif Jalal

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Validation Controls
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Validation Controlspages 116 119

• An important aspect of creating ASP.NET Web pages
  for user input is to be able to check that the
  information users enter is valid. ASP.NET
  provides a set of validation controls that
  provide an easy-to-use but powerful way to check
  for errors and, if necessary, display messages to
  the user.
• Validation Controls are used to compare your form
  field controls to a rule.
• Validation Controls are also used to configure
  the rules to validate the contents of form
  fields.
• The Validation Controls inherit from the Base
  Validator class, which inherits from the Label
  class.

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Types of Validation Controls

• RequiredFieldValidator
• RangeValidator
• CompareValidator
• RegularExpressionValidator
• CustomValidator
• ValidationSummary

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RequiredFieldValidator

• Ensures that the user does not skip an entry.
• Ensures if a value is entered or selected.
• If the field is cleared, the user sees an error
  message immediately when leaving the field.
• In server-side validation, no checking is done
  until the page is submitted, so the user will not
  see an error message until after the page is
  submitted.

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RangeValidator

• Checks whether the value of an Input control is
  within a specified range of values.
• In addition to ControlToValidate property, you
  must assign the Minimum and Maximum Value
  properties to specify range.
• Data types that can be compared are strings,
  integers, doubles, dates, and currency.

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CompareValidator

• Compares a user's entry against a constant value,
  against the value of another control (using a
  comparison operator such as less than, equal, or
  greater than), or for a specific data type.
• You must specify the Input control to validate by
  setting the ControlToValidate property.
• If you want to compare a specific Input control
  with another Input control, then set
  ControlToCompare property.
• If you want to compare the Input control with a
  constant value, then set ValueToCompare property.
• Must use the Operator property to specify the
  type of comparison to perform between Input
  control and ControlToControl or ValueToControl.

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RegularExpressionValidator

• You can create your own validation rules by
  building a Regular Expression.
• Checks that the entry matches a pattern defined
  by a regular expression.
• This type of validation enables you to check for
  predictable sequences of characters, such as
  those in e-mail addresses, telephone numbers,
  postal codes, and so on.

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CustomValidator

• Performs user-defined validation on an input
  control.
• Checks the user's entry using validation logic
  that you write yourself.
• This type of validation enables you to check for
  values derived at run time.

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ValidationSummary

• ValidationSummary control isused to summarize
  the error messages from validators ona web page,
  in one location.
• You can display the summary as a list, bulleted
  list, or a single paragraph by setting the
  DisplayMode property.
• You can display an additional messge in a alert
  by setting the ShowMessageBox property.
• ValidationSummary control does not validate any
  input, rather, it only summarizes the errors in
  one point.

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ValidationControls - Summary

• RequiredFieldValidator
• Makes sure a form field is not left blank.
• RangeValidator
• Makes sure a fields value falls within a given
  range.
• CompareValidator
• Compares a fields value with other values or
  other fields values.
• RegularExpressionValidator
• Evaluates data against a regular expression.
• CustomValidator
• Evaluates data against custom criteria.
• ValidationSummary
• Does not validate rather provides summary of all
  errors.

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HomeWork

• Do Panel exercise on page 111.
• Do PlaceHolder exercise on page 113.
• Create different validation controls.