Dynamically constructing filters in SQLAlchemy

Question

I am looking for a way to dynamically construct filters using SQLAlchemy. That is, given the column, the operator name and the comparing value, construct the corresponding f

Answer 1

class Place(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    search_id = db.Column(db.Integer, db.ForeignKey('search.id'), nullable=False)

    @classmethod
    def dinamic_filter(model_class, filter_condition):
        '''
        Return filtered queryset based on condition.
        :param query: takes query
        :param filter_condition: Its a list, ie: [(key,operator,value)]
        operator list:
            eq for ==
            lt for <
            ge for >=
            in for in_
            like for like
            value could be list or a string
        :return: queryset
        '''
        __query = db.session.query(model_class)
        for raw in filter_condition:
            try:
                key, op, value = raw
            except ValueError:
                raise Exception('Invalid filter: %s' % raw)
            column = getattr(model_class, key, None)
            if not column:
                raise Exception('Invalid filter column: %s' % key)
            if op == 'in':
                if isinstance(value, list):
                    filt = column.in_(value)
                else:
                    filt = column.in_(value.split(','))
            else:
                try:
                    attr = list(filter(lambda e: hasattr(column, e % op), ['%s', '%s_', '__%s__']))[0] % op
                except IndexError:
                    raise Exception('Invalid filter operator: %s' % op)
                if value == 'null':
                    value = None
                filt = getattr(column, attr)(value)
            __query = __query.filter(filt)
        return __query

Execute like:

places = Place.dinamic_filter([('search_id', 'eq', 1)]).all()