MIS 3200 – Unit 2.2
• Outline
– What’s the problem with bad data?
– Traditional solutions
– ASP.NET tools – Validators
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•
•
•
RequiredFieldValidator
RangeValidator
CompareValidator
ValidationSummary
What’s the problem
• BAD DATA!
– Bad input data
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•
•
•
Incorrect format
Illegal values
Illogical values
Illegal characters
03/30/12
-5/03/2012
30/03/2012
##/03/2012
– Illegal operations (e.g. division by zero)
03/30/2013
Traditional Solutions
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•
•
•
Data entry professionals
Double entry procedures
Self-checking numbers
Program code
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 email address to contain “@” and “.”
How Validators Work
• ControlToValidate property
– tells the validator which TextBox to validate
• Placed next to the control they to validate
• User feedback
Remember these user
– Text
– ErrorMessage
feedback properties
• “Fire” (be triggered) when a button is clicked
or when focus passes to another control.
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
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
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
Design view
After Running and pressing Try It
linked to all validators on the page
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
CV Example
• 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
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
RangeValidator - RV
• 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
RV Example
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•
An entry is required
Please enter a number in the range
RFV and RV
Note: this works fine for data
types double and decimal
Try it Out – L2.2
1.
2.
3.
4.
5.
6.
7.
8.
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
L2.2 #2
9. Open the file in Design view
10. Drop a RequiredFieldValidator to the right of your first
TextBox
a.
b.
c.
d.
e.
f.
g.
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
L2.2 #3
11 Drop a CompareValidator to the right of your
RequiredFieldValidator
a.
b.
c.
d.
e.
f.
g.
h.
i.
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
L2.2 #4
12 Repeat steps 10 and 11 for the second TextBox, changing
names and messages as required
13 Drop another CompareValidator after the second TextBox
14 Repeat all of step 11 again for the 2nd CV with the following
differences:
a.
b.
c.
d.
e.
f.
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)
L2.2 #5
15 Drop a ValidationSummary after lblOutput
a. Change its ForeColor to red
16 Run the page trying various combinations of values
a.
b.
c.
d.
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
17 Change the page heading to Unit 2.2 L2.2 – Simple
Calculator with Validation
L2.2 – Sample Output
L2.2 – Final steps
18 Open your MIS3200 home page in the MIS3200
folder
19 Add another hyperlink for unit 2
a. (ID) = hlU22L22
b. Text = Unit 2.2 L2.2
c. NavigateUrl = the page you just modified
20 Copy ASPPub back to ASPNET and submit your MIS
Portfolio URL to the drop box
Think About It!
• Why are validators important?
• When do you use the following:
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–
–
–
RequiredFieldValidator
RangeValidator
CompareValidator
ValidationSummary