FilterStrategy.py

"""
class for filter strategies. Subclasses must implement 'filter' method.
"""
class FilterStrategy:

    """Abstract method for filtering books by a specific criterion."""
    def filter(self, books, value):
        raise NotImplementedError("This method should be implemented by subclasses.")

#Filters books by title.
class TitleFilter(FilterStrategy):
    def filter(self, books, value):
        return books[books['title'].str.contains(value, case=False, na=False)]

#Filters books by author.
class AuthorFilter(FilterStrategy):
    def filter(self, books, value):
        return books[books['author'].str.contains(value, case=False, na=False)]

#Filters books by genre.
class GenreFilter(FilterStrategy):
    def filter(self, books, value):
        return books[books['genre'].str.contains(value, case=False, na=False)]

#Filters books by year.
class YearFilter(FilterStrategy):
    def filter(self, books, value):
        try:
            year = int(value)
            return books[books['year'] == year]
        except ValueError:
            return books[0:0]