[mod_python] Validating input - Form Handler component

Hi !

Do you knows about a Form handler component (module, class, unit, 
package, etc.) that can uniformize the form handling on the web ?

The html form handling forces me to I repeat some of the codes in many 
modules.

Example:
1. Init
2. Get inputs
3. Validating inputs: check field names, data types, I need to open 
queries to see that actual data is valid (and existing), require all the 
fields I need to make the next step, convert data from text to any type, 
protect fields from SQL injection, etc.
3. Make operation (insert, update, delete, or select)
4. Show the results, build the result table and/or the form again.

These steps are repeating modules by modules...

Do you heard about something like this, or I need to write this component ?

Thanks for your help:
dd