Validation Server Control

ASP.NET has built in controls that enable incredibly easy validation creation. By using different validator controls and ValidationSummary control even a complex validation process can be done very fast. You can just drag and drop validation controls to the form, map them to form fields and you have a client-side validation. Creating server side validation is simple as well. You can use C# or VB.NET to perform even the extremely complex validation process.

Available validation server controls

Validation Server Control

RequiredFieldValidator
Ensures that the user does not skip a form entry field

CompareValidator
Allows for comparisons between the user’s input and another item using a comparison operator (equals, greater than, less than, and so on)

RangeValidator
Checks the user’s input based upon a lower- and upper-level range of numbers or characters

RegularExpressionValidator
Checks that the user’s entry matches a pattern defined by a regular expression. This is a good control to use to check e-mail addresses and phone numbers

CustomValidator
Checks the user’s entry using custom-coded validation logic

ValidationSummary
Displays all the error messages from the validators in one specific spot on the page

The CustomValidator Control

The final control we have included in ASP.NET is one that adds great flexibility to our validation abilities. We have a custom validator where we get to write out own functions and pass the control value to this function.
Field:
*

>

We notice that there are two new attributes ClientValidationFunction and OnServerValidate. These are the tell the validation control which functions to pass the controltovalidate value to. ClientValidationFunction is usually a javascript funtion included in the html to the user. OnServerValidate is the function that is server-side to check for validation if client does not support client-side validation.
Client Validation function:
&ltscript language=”Javascript”>

>

Server Validation function:
Sub ServerValidate (objSource As Object, objArgs As ServerValidateEventsArgs)
‘ Code goes here
End Sub
b

The RegularExpressionValidator Control

The regular expression validator is one of the more powerful features of ASP.NET. Everyone loves regular expressions. Especially when you write those really big nasty ones… and then a few days later, look at it and say to yourself. What does this do?
Again, the simple usage is:
E-mail:
*

>

The RangeValidator Control

Range validator control is another validator control which checks to see if a control value is within a valid range. The attributes that are necessary to this control are: MaximumValue, MinimumValue, and Type.
Sample:
Enter a date from 1998:

*
>

The CompareValidator Control

Next we look at the CompareValidator Control. Usage of this CompareValidator is for confirming new passwords, checking if a departure date is before the arrival date, etc. We’ll start of with a sample:
Textbox 1:
Textbox 2:
*

>

Here we have a sample where the two textboxes must be equal. The tags that are unique to this control is the ControlToCompare attribute which is the control that will be compared. The two controls are compared with the type of comparison specified in the Operator attribute. The Operator attribute can contain Equal, GreterThan, LessThanOrEqual, etc.
Another usage of the ComapareValidator is to have a control compare to a value. For example:
Field:
*

>

The data type can be one of: Currency, Double, Date, Integer or String. String being the default data type.

The RequiredFieldValidation Control

The first control we have is the RequiredFieldValidation Control. As it’s obvious, it make sure that a user inputs a value. Here is how it’s used:
Required field:
*

>

In this example, we have a textbox which will not be valid until the user types something in. Inside the validator tag, we have a single *. The text in the innerhtml will be shown in the controltovalidate if the control is not valid. It should be noted that the ErrorMessage attribute is not what is shown. The ErrorMessage tag is shown in the Validation Summary (see below).

Validator Control Basics

With ASP.NET, there are six(6) controls included. They are:
• The RequiredFieldValidation Control
• The CompareValidator Control
• The RangeValidator Control
• The RegularExpressionValidator Control
• The CustomValidator Control

Validator Control Basics
All of the validation controls inherit from the base class BaseValidator so they all have a series of properties and methods that are common to all validation controls. They are:
• ControlToValidate – This value is which control the validator is applied to.
• ErrorMessage – This is the error message that will be displayed in the validation summary.
• IsValid – Boolean value for whether or not the control is valid.
• Validate – Method to validate the input control and update the IsValid property.
• Display – This controls how the error message is shown. Here are the possible options:
• None (The validation message is never displayed.)
• Static (Space for the validation message is allocated in the page layout.)
• Dynamic (Space for the validation message is dynamically added to the page if validation fails.)

Can you edit data in the Repeater control?

No, it just reads the information from its data source.

Which method do you invoke on the DataAdapter control to load your generated dataset with data?

The Fill() method.

Whats MSIL, and why should my developers need an appreciation of it if at all?

MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL. MSIL also allows the .NET Framework to JIT compile the assembly on the installed computer.