Recursive Category Table in Python

admin — Sat, 13 Jun 2009 16:16:59 +0000

While working with a project, the problem with the recursive category table being built came up. The table holds the parent_id of the category name and the result is a list with the id and the name of the category. The category name is prepended with spaces equivalent to the level of indentation.

model:

class AchievementCategory(DeclarativeBase):
	__tablename__ = 'achievement_categories'

	id = Column(mysql.MSBigInteger(20, unsigned = True), primary_key = True)
	parent_id = Column(mysql.MSBigInteger(20, unsigned = True), default = 0)
	name = Column(Unicode(80))

code:

def get_cats(n = 0, c_list = [], level = 0):
	sql = DBSession.query(AchievementCategory).filter_by(parent_id = n).order_by(AchievementCategory.name).all()
	for e in sql:
		c_list.append([e.id, level * " " + e.name, level])
		get_cats(e.id, c_list, level+1)
	return c_list

print get_cats()

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Recursive Category Table in Python