Building a Loan Payment Calculator using ASP.NET 2.0 - Use of validation controls

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Validation controls have been added to the design view to make sure values are inserted into the required text boxes and inserted values do not violate some basic rules. The validator controls can be dragged and dropped into the required cells in the Messages column of the table.

RequiredFieldValidators

In the design view of the finPMT.aspx page you may see a number of validation controls in the Messages column. For example, "Enter a number" for all the text boxes relates to the RequiredFieldValidators. Although they read "Enter a number," what is really meant by the RequiredFieldValidator is that the text boxes should not be empty. These are checked as you enter the values. To test them just hit the button without making entries to any of the boxes. You will be asked to enter a number before you can proceed. The properties of the RequiredFieldValidator1 in the first row are as shown in the next picture.

RegularExpressionValidator

You will find this validator in the first row, which has the error message, "Only numbers allowed." The reason for this is that, since this text box takes a rate, some users may enter something like 7% instead of 7. This validator would caution the user to change it to a number. The w in the Validator Expression property would trigger any violation of this rule. The regular expression for number is w. If you need to know more about regular expressions that you can use in the VS 2003 IDE you need to look up the regex classes located in the namespace System.Text.RegularExpressions.

RangeValidator

In the second row in the design view, in addition to a RequiredFieldValidator there is an additional RangeValidator. This calculator is configured for a loan life of 30 years which is 360 pay periods. Its value can range from 1 to 360. Any other number in this text box will not be validated. The RangeValidator property in the second row is shown in the next picture.

Next: Source code for the finPMT.aspx page >>
 

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· IS the article mission the implementation of Pmt?    · This tutorial was written to expose the properties and methods of the...    · I meant MISSING, not mission. Sorry.    · The PMT is a function that takes couple of arguments described in the article and...   >>> Post your comment now!