[Python] How to set an Array column with an empty array as default in SQLAlchemy + Postgres

I want to list the sources of a piece of information. Instead of creating another table with a one to many relation, I tought I'd use the Array type.

To I tried:

app = Flask(__name__)
db = SQLAlchemy(app)

...

class Edge(db.Model):

sources = db.Column(
db.ARRAY(db.String),
default=db.ARRAY(db.String)
)


But adding an edge gives me this error:

ProgrammingError: (psycopg2.ProgrammingError) can't adapt type 'ARRAY' [SQL: 'INSERT INTO edges (child_id, parent_id, sources) VALUES (%(child_id)s, %(parent_id)s, %(sources)s'] [parameters: {'child_id': 20, 'parent_id': 26, 'sources': ARRAY(String())}]
​

I can't find a good tutorial on how to use an array column with a default empty array.

Thanks

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