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VB.NET 2005

  1. VB.NET 2005 Free Training
  2. The .NET Framework Architecture Part 1
  3. The .NET Framework Architecture Part 2
  4. Application Class and Message Class
  5. Implementing Class Library Object
  6. Visual Studio.NET Namespaces
  7. .NET Assemblies
  8. Differences between VB.NET 1.0 and VB.NET 2.0
  9. Introducing VB.NET Windows Forms
  10. Visual Studio Windows Forms Designer
  11. Exploring the Forms Designer generated code
  12. Setting and Adding Properties to Windows Form
  13. Implementing Inheritance
  14. Event Handling In Visual Basic .NET
  15. Building Graphical Interface elements
  16. .NET Common Windows Forms Controls Part 1
  17. .NET Common Windows Forms Controls Part 2
  18. Common Controls and Handling Control Events
  19. DomainUpDown and NumericUpDown Controls
  20. Dialog Boxes in Visual Basic .NET
  21. Visual Studio Adding Controls to Windows Form
  22. VB.NET Validation Controls
  23. Working with Menu Controls
  24. VB.NET MDI Applications
  25. .NET Exceptions
  26. VB.NET Creating and Managing Components Part 1
  27. VB.NET Creating and Managing Components Part 2
  28. Simple Data Binding
  29. .NET Complex Data Binding
  30. .NET Data Form Wizard
  31. Data Manipulation with ADO.NET
  32. SQL Server Stored Procedures
  33. SQL Server Ad Hoc Queries
  34. Finding and Sorting Data in DataSets
  35. ADO.NET Object Model
  36. Working with DataSets
  37. Using XML Data
  38. Working with File System in .NET
  39. Creating Web Service
  40. Instantiating - Invoking Web Services, Creating Proxy Classes with WSDL
  41. Web Reference and Web Services
  42. Web Services - SOAP, WSDL, Disco and UDDI
  43. Web Application Testing in VB.NET 2005
  44. Web Application Tracing and Debugging
  45. Working with Legacy Code and COM Components
  46. ActiveX Controls and Legacy Code
  47. Windows Application Testing
  48. VB.NET Windows Application Testing
  49. Tracing VB.NET Windows Application
  50. Debugging Windows Applications In Visual Studio.NET 2005
  51. Deploying Windows Applications In Visual Studio.NET 2005
  52. Customizing Setup Project in Visual Studio.NET 2005
  53. Shared Assembly
  54. Microsoft .NET Creating Installation Components
  55. The Registry Editor in Visual Studio.NET 2005
  56. The File Types Editor

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Home arrow Technical Training arrow VB.NET 2005

VB.NET Validation Controls

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Author : Exforsys Inc.     Published on: 4th Jul 2005    |   Last Updated on: 14th Mar 2009

VB.NET Validation Controls 

In this tutorial you will learn about User Input Validation, Required Field Validators, Comparison Validators, Range Validators, Regular Expression Validator, Custom Validators, ErrorProvider, Enabling Controls Based On Input and Other Properties of Validation.

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User Input Validation

While any application can be designed with sound logic and good technology and can deliver high performance with accuracy, some errors could still creep into it. This could be due to wrong inputs by users. While the programmer may have taken care of all the exceptions it could cause a loss of business goodwill if a customer is confronted with an error message after he has input data into a number of fields. All of us are familiar with warnings like “Please enter a valid ZIP” or “Please Enter Your First Name!” and so on!

Thus some client side validations ensure that correct data is sent to the application. We can ensure such validations using validation controls. .NET Framework provides several controls for different types of validations.

The validation Controls that are available in .Net Framework are given below:

Control

Description

RequiredFieldValidator Ensures that the user enters data in the associated data-entry control
CompareValidator Uses comparison operators to compare user-entered data to a constant value or the value in another data-entry control
RangeValidator Ensures that the user-entered data is in a range between given lower and upper bounds
RegularExpressionValidator Ensures that the user entered data matches a regular expression pattern
CustomValidator Ensures that the user-entered data passes validation criteria that you set yourself

Required Field Validators

This is one of the simplest controls to use. This validating control makes sure that the users have entered data into a data-entry control. For example, you may want to make sure that users enter their mail id or their credit card number before they proceed to submit the form. The RequireFieldValidator control will ensure that the user will not be able to complete the form submission with null value for the field associated with this control.

The InitialValue property of this control has an initial value set to an empty String (“”) by default. The control raises an error message if this value does not change when validation occurs.

The other controls do not perform validation if the data entry field is empty and make it appear that the validation succeeded when no validation check has been performed. Therefore, it is imperative that a validation check be performed before other checks are activated.

Comparison Validators

This control is used to validate the value entered in to one data entry control by comparing it with the data entered in to another control. The ControlToValidate property sets the field to be validated. The ControlToCompare property specifies the control to compare with. You can also validate the data from constant value by setting the property ValueToCompare. When you set both the ControlToCompare and ValueToCompare then ControlToCompare takes precedence.

The Operator property sets the type of comparison that will be performed.

Table showing the values for Operator property:

Value

Description

Equal Checks if the comared values are equal
NotEqual Checks if the compared values are not equal
GreaterThan Checks for greater than relationship
GreaterThanEqual Checks for greater than or equal relationship
LessThan Checks for Less than relationship
LessThanEqual Checks for less than or equal relationship
DataTypeCheck Compares the data types between the value entered into the data-entry control that is validated and the data type specified by the Type property

The type property can have any of the following values:

  • String
  • Integer
  • Double
  • Date
  • Currency

Range Validators

A range validator test is used to check if the value entered in the data-entry control is within a specified range of values. The property ControlToValidate is set to the control that contains the data which is to be validated. The property MinimumValue sets the minimum value of the range. The property MaximumValue sets the maximum value of the range. The property Type sets the date type of the values to be compared. All the types of comparisons discussed above are still valid for this also.

Regular Expression Validator

RegularExpressionValidator control is used to check if the value in a data-entry control matches a pattern defined by a regular expression. You can check even the format of the text entered. Regular expressions are generally made up of test with embedded codes that start with a backslash (). For instance a simple expression for checking for either a uppercase or lower case alphabet is given by the expression “ b[A-ZA-z]+b.

Custom Validators

This control allows the developer freedom to define his own validations. The property ClientValidationFunction property sets the name of function or script that will do the validation. This function takes two parameters. The first argument source identifies the source control to validate. The second argument arguments hold the data to validate.

The Causes Validation Property

CausesValidation is one of the public instance properties of the control class, which specifies whether all controls which require validation gets it when the control gets focus. It returns true if the control causes validation to be performed on any controls requiring validation when it receives focus and false otherwise.

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Validating event occurs when the control is validating at the time when the control loses the focus if the control’s CausesValidation property is true. Any code executed in response to this event can be used to throw exception if any is found. Validated Event occurs when the control has completed validation. This event occurs if no exception was thrown in the validating event. Clearing up the error provider messages can be done here.



 
This tutorial is part of a VB.NET 2005 tutorial series. Read it from the beginning and learn yourself.

VB.NET 2005

  1. VB.NET 2005 Free Training
  2. The .NET Framework Architecture Part 1
  3. The .NET Framework Architecture Part 2
  4. Application Class and Message Class
  5. Implementing Class Library Object
  6. Visual Studio.NET Namespaces
  7. .NET Assemblies
  8. Differences between VB.NET 1.0 and VB.NET 2.0
  9. Introducing VB.NET Windows Forms
  10. Visual Studio Windows Forms Designer
  11. Exploring the Forms Designer generated code
  12. Setting and Adding Properties to Windows Form
  13. Implementing Inheritance
  14. Event Handling In Visual Basic .NET
  15. Building Graphical Interface elements
  16. .NET Common Windows Forms Controls Part 1
  17. .NET Common Windows Forms Controls Part 2
  18. Common Controls and Handling Control Events
  19. DomainUpDown and NumericUpDown Controls
  20. Dialog Boxes in Visual Basic .NET
  21. Visual Studio Adding Controls to Windows Form
  22. VB.NET Validation Controls
  23. Working with Menu Controls
  24. VB.NET MDI Applications
  25. .NET Exceptions
  26. VB.NET Creating and Managing Components Part 1
  27. VB.NET Creating and Managing Components Part 2
  28. Simple Data Binding
  29. .NET Complex Data Binding
  30. .NET Data Form Wizard
  31. Data Manipulation with ADO.NET
  32. SQL Server Stored Procedures
  33. SQL Server Ad Hoc Queries
  34. Finding and Sorting Data in DataSets
  35. ADO.NET Object Model
  36. Working with DataSets
  37. Using XML Data
  38. Working with File System in .NET
  39. Creating Web Service
  40. Instantiating - Invoking Web Services, Creating Proxy Classes with WSDL
  41. Web Reference and Web Services
  42. Web Services - SOAP, WSDL, Disco and UDDI
  43. Web Application Testing in VB.NET 2005
  44. Web Application Tracing and Debugging
  45. Working with Legacy Code and COM Components
  46. ActiveX Controls and Legacy Code
  47. Windows Application Testing
  48. VB.NET Windows Application Testing
  49. Tracing VB.NET Windows Application
  50. Debugging Windows Applications In Visual Studio.NET 2005
  51. Deploying Windows Applications In Visual Studio.NET 2005
  52. Customizing Setup Project in Visual Studio.NET 2005
  53. Shared Assembly
  54. Microsoft .NET Creating Installation Components
  55. The Registry Editor in Visual Studio.NET 2005
  56. The File Types Editor
 

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