1. MIS 3200 – Unit 2.2 Outline What’s the problem with bad data?
Traditional solutions
ASP.NET tools – Validators
RequiredFieldValidator
RangeValidator
CompareValidator
ValidationSummary

2. What’s the problem BAD DATA! Bad input data
Incorrect format
Illegal values
Illogical values
Illegal characters
Illegal operations (e.g. division by zero)
03/30/2013
03/30/12
-5/03/2012
30/03/2012
##/03/2012

3. Traditional Solutions
Data entry professionals
Double entry procedures
Self-checking numbers
Program code

4. Solution: Validators Controls that do error checking, such as
Require an entry:
Provide a credit card number
Within a specified range
Year of birth should be between 1900 and 2000
Compare an entry to a predetermined value
Retype your password, and they should match
Compare an entry the value of another control
Require an address to contain and “.”

5. How Validators Work ControlToValidate property
tells the validator which TextBox to validate
Placed next to the control they to validate
User feedback
Text
ErrorMessage
“Fire” (be triggered) when a button is clicked or when focus passes to another control.
Remember these user feedback properties

6. RequiredFieldValidator - RFV
Typically associated with a TextBox
Fires if nothing is entered in the TextBox
When the validator fires it displays a message
If only one of the validator’s ErrorMessage and Text properties has a value then that value is displayed
If both ErrorMessage and Text have values then the value of Text is displayed at the location of the validator and the value of ErrorMessage is displayed in a ValidationSummary control if there is one on the page

7. RFV Example txtNum1 Running version before pressing Try It
Running version after pressing Try It
Error message color set to red
No value set for Text

8. RFV Example 2
Validation problems often need more text than what can be accommodated next to the web control.
Use ValidationSummary control and the ErrorMessage property
linked to all validators on the page
Design view
After Running and pressing Try It

9. CompareValidator - CV Compare an entry to a predetermined value
ControlToCompare if you want to compare to another Control
or the value of another control
ValueToCompare to compare to a predetermined value
To prevent missing data while comparing,
MUST be used with a RequiredFieldValidator
CV only fires if there is something to validate

10. CV Example Allows you to chose the type of comparison
Allows you to chose the data type
Default type is string
Allows you to chose the type of comparison
Default is a test for equality
Allows you to set focus on the problematic data when the validator fires
Recall: the Focus() method

11. CV Example To compare to another control
RequiredFieldValidator CompareValidator
Entry is not > 10
Entry is a whole number > 10
Entry is not a whole number

12. RangeValidator - RV Has the same Type choices as the CV
Similar to the CompareValidator but has a
MinimumValue and a MaximumValue (instead of a ValueToCompare or FieldToCompare)
Has the same Type choices as the CV
Has the same SetFocusOnError option

13. RV Example
An entry is required
Please enter a number in the range
RFV and RV
Note: this works fine for data types double and decimal

14. Try it Out – L2.2 Make sure ASPPub is on your desktop
Start VWD and open ASPPub
Open the Unit2 folder under MIS3200
Click on yourLastNameU2L2.aspx file
Right-click and copy
Click on the Unit2 folder
Right-click and paste
Change the file name to yourLastNameU2L22.aspx

15. L2.2 #2 Open the file in Design view
Drop a RequiredFieldValidator to the right of your first TextBox
Change the (ID) to rfvNum1
Change the ControlToValidate to txtNumber1
Change the ErrorMessage to Number 1 is required
Change the Text to *
Change ForeColor to red
Change SetFocusOnError to true
Change the Display to Dynamic

16. L2.2 #3
Drop a CompareValidator to the right of your RequiredFieldValidator
Set the (ID) to cvNumber1
Set ControlToValidate to txtNumber1
Change ErrorMessage to Number 1 must be a valid number
Change Text to *
Change SetFocusOnError to true
Change the ForeColor to red
Change Operator to DataTypeCheck
Change Type to Double
Change the Display to Dynamic

17. L2.2 #4
Repeat steps 10 and 11 for the second TextBox, changing names and messages as required
Drop another CompareValidator after the second TextBox
Repeat all of step 11 again for the 2nd CV with the following differences:
Set the (ID) to cvNumber2Zero
Set the error message to Number 2 can’t be zero
Set Operator to NotEqual
Set ValueToCompare to 0 (a zero)
Set the ControlToValidate to txtNumber2
Do NOT set the Type (if you do delete the validator and repeat)

18. L2.2 #5 Drop a ValidationSummary after lblOutput
Change its ForeColor to red
Run the page trying various combinations of values
Press + with nothing in the text boxes
Put a number in one text box but not the other
Put non-numeric data in one text box or the other
Put zero in the second text box
Change the page heading to Unit 2.2 L2.2 – Simple Calculator with Validation

19. L2.2 – Sample Output

20. L2.2 – Final steps Open your MIS3200 home page in the MIS3200 folder
Add another hyperlink for unit 2
(ID) = hlU22L22
Text = Unit 2.2 L2.2
NavigateUrl = the page you just modified
Copy ASPPub back to ASPNET and submit your MIS Portfolio URL to the drop box

21. Think About It! Why are validators important?
When do you use the following:
RequiredFieldValidator
RangeValidator
CompareValidator
ValidationSummary