How to filter words in db.body

I am working on a program that I want to filter out some words, with nltk style of removing the stopwords as follows:

def phrasefilter(phrase):
    phrase = phrase.replace('hi', 'hello')
    phrase = phrase.replace('hey', 'hello')
    phrase = re.sub('[^A-Za-z0-9\s]+', '', phrase.lower())
    noise_words_set = ['of', 'the', 'at', 'for', 'in', 'and', 'is', 'from', 'are', 'our', 'it', 'its', 'was', 'when', 'how', 'what', 'like', 'whats', 'now', 'panic', 'very']
    return ' '.join(w for w in phrase.split() if w.lower() not in noise_words_set)

Is there a way of doing this on web2py DAL.

db.define_table( words,
    Field(words1, REQUIRES  IS_NOT_NULL(), REQUIRES....

I want to put it in the REQUIRES IS_NOT_IN_NOISE_WORDS_SET() constraints for example. Is this possible? Am working on a user input( with strings saved to the db) where it automatically deletes the stopwords I have chosen instead of the using the snippet shown above.

Copyright Notice：Content Author:「lobjc」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/30772123/how-to-filter-words-in-db-body