def get_m2m_value(session, request, obj):
    """ Set m2m value for model obj from request params like "group[]"

        :Parameters:

            - `session`: SQLAlchemy DBSession
            - `request`: request as dict
            - `obj`: model instance
    """
    params = {}
    ''' m2m_request:

        {u'company[]': [u'["id", 1]'],
         u'professions[]': [u'["id", 2]', u'["id", 3]']}
    '''
    m2m_request = {k: v for k, v in list(request.items()) if k.endswith('[]')}
    for k, v in list(m2m_request.items()):
        key = k[:-2]
        relation = getattr(obj.__class__, key, False)
        if not relation:
            relation = getattr(obj, key, False)
        if not relation:
            continue  # pragma: no cover
        value = get_m2m_objs(session, relation, v)
        if value is None:
            continue

        if relation.property.uselist is False:
            if value:
                value = value[0]
            else:
                value = None
        params[key] = value
    return params