Convert SqlAlchemy orm result to dict

Question

How to convert SQLAlchemy orm object result to JSON format?

Currently I am using sqlalchemy reflection to reflect tables from the DB. Consider I have a User table an

Answer 1

You can use the relationships property of the mapper. The code choices depend on how you want to map your data and how your relationships look. If you have a lot of recursive relationships, you may want to use a max_depth counter. My example below uses a set of relationships to prevent a recursive loop. You could eliminate the recursion entirely if you only plan to go down one in depth, but you did say "and so on".

def object_to_dict(obj, found=None):
    if found is None:
        found = set()
    mapper = class_mapper(obj.__class__)
    columns = [column.key for column in mapper.columns]
    get_key_value = lambda c: (c, getattr(obj, c).isoformat()) if isinstance(getattr(obj, c), datetime) else (c, getattr(obj, c))
    out = dict(map(get_key_value, columns))
    for name, relation in mapper.relationships.items():
        if relation not in found:
            found.add(relation)
            related_obj = getattr(obj, name)
            if related_obj is not None:
                if relation.uselist:
                    out[name] = [object_to_dict(child, found) for child in related_obj]
                else:
                    out[name] = object_to_dict(related_obj, found)
    return out

Also, be aware that there are performance issues to consider. You may want to use options such as joinedload or subqueryload in order to prevent executing an excessive number of SQL queries.