SQLAlchemy JSON column - how to perform a contains query

Question

I have the following table in mysql(5.7.12):

class Story(db.Model):
    sections_ids = Column(JSON, nullable=False, default=[])

sections_ids is basicly a list of integers [1, 2, ...,n]. I need to get all rows where sections_ids contains X. I tried the following:

stories = session.query(Story).filter(
        X in Story.sections_ids
    ).all()

but it throws:

NotImplementedError: Operator 'contains' is not supported on this expression

Solution 1

Use JSON_CONTAINS(json_doc, val[, path]):

from sqlalchemy import func

# JSON_CONTAINS returns 0 or 1, not found or found. Not sure if MySQL
# likes integer values in WHERE, added == 1 just to be safe
session.query(Story).filter(func.json_contains(Story.section_ids, X) == 1).all()

As you're searching an array at the top level, you do not need to give path. Alternatively beginning from 8.0.17 you can use value MEMBER OF(json_array), but using it in SQLAlchemy is a little less ergonomic in my opinion:

from sqlalchemy import literal

# self_group forces generation of parenthesis that the syntax requires
session.query(Story).filter(literal(X).bool_op('MEMBER OF')(Story.section_ids.self_group())).all()

Solution 2

For whoever get here, but is using PostgreSQL instead: your fields should be of the type sqlalchemy.dialects.postgresql.JSONB (and not sqlalchemy_utils.JSONType) -

Then you can use the Comparator object that is associated with the field with its contains (and others) operators.

Example:

Query(Mymodel).filter(MyModel.managers.comparator.contains(["[email protected]"]))

(note that the contained part must be a JSON fragment, not just a string)

Comments

[Ilja Everilä]

You can read about generic functions in SQLA here.

[Shoham]

Are you sure thats the right syntax? its not working for me... no error is raised... it just not continue to the next line...

[Shoham]

Should be str(X)... (in my case X was int and only when casting to string it worked). THANKS!

[Toufeeq]

I want to do the searching at 2nd level, how to specify the path?

[Ilja Everilä]

@toufeeq Pass it as the 3rd argument.

[Toufeeq]

@IljaEverilä I mean to ask, how to pass the wildcard path $[*].some_field. Since * is not allowed in sqlalchemy query

[Ilja Everilä]

It is MySQL that does not allow a wildcard in a json path with JSON_CONTAINS. Instead you could search for an object with the required key-value pair: func.json_contains(Foo.bar, func.json_object("some_field", "some_value")).

[Dave]

MyModel.managers in this case is the column name ("managers"), not some special keyword.