SQLALchemy-Utils: Use '~' operator with LTree

flask, flask-sqlalchemy, sqlalchemy

Solution

I was able to solve this issue with this piece of code.

Courtesy Github-Issues: SQLAlchemy-Util Issues (253)

 from sqlalchemy.sql import expression
 from sqlalchemy_utils.types.ltree import LQUERY

 custom_lquery = '*.some.pattern'
 Model.query.filter(Model.path.lquery(expression.cast(custom_lquery, LQUERY))).all()

Problem

I am trying to query Postgres materialized path view(ltree) using Flask,SQLAlchemy-Utils and Flask-SQLAlchemy. SQLAlchemy-Util Docs shows the usage of '==', '!=' operators using LTree. How can i use '~' operator? I saw the code in sqlalchemy_utils/ltree.py: ``` class comparator_factory(types.Concatenable.Comparator): def ancestor_of(self, other): if isinstance(other, list): return self.op('@>')(expression.cast(other, ARRAY(LtreeType))) else: return self.op('@>')(other) def descendant_of(self, other): if isinstance(other, list): return self.op('<@')(expression.cast(other, ARRAY(LtreeType))) else: return self.op('<@')(other) def lquery(self, other): if isinstance(other, list): return self.op('?')(expression.cast(other, ARRAY(LQUERY))) else: return self.op('~')(other) def ltxtquery(self, other): return self.op('@')(other) ``` This is subclass of LtreeType. For a simple `==`, i am using : ``` Model.query.filter(Model.path == LTree('1.2')).all() ``` But using this expression throws validation error: ``` Model.query.filter(Model.path == LTree('~1.2')).all() ``` How can i format above expression in a valid SQLALchemy query?

Original source