For example, you can have an input field that should not be empty, should be less than 25 chars and should be alpha-numeric. In some dynamically programmed pages, it may be required to change the validations in the form at run time.
In other words, in order to validate a field, you just associate a set of validation descriptors for each input field in the form. For such cases, a function is included which clears all validations in the validator object. Note that this validation if for fields like Textbox and multi-line text box.
When you use the form data in an SQL query, it should be validated against SQL Injection.
When you have fields like name or email as mandatory in the form, it should be checked in the server side script as well. Here is the sample output from that script: Note that the “Filling” checkbox group in the HTML form results in an array in the PHP script The rest of the fields appear as simple name-value pairs To validate mandatory fields, we just have to check the presence of the value in the $_POST array.
The validations also help in lesser server side errors.
For example, if you have set length limit in the database for a text input, it is better to do the validation before it actually gets cut off by the database system or even getting an error thrown.
Often, people confuse form validations with form security.
The script has a catalog of almost all the common validation types built-in.
The idea is to create a set of “validation descriptors” associated with each element in a form.
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