Some thoughts on column refactoring in pycroft (#52)

col_refactoring.py

# pylint: disable=all


# Original idea:

@bp.route("/<int:user_id>/hosts")
def user_show_hosts_json(user_id):
    list_items = []
    for user_host in User.q.get(user_id).user_hosts:
        # …
        for ip in user_host.ips:
            # use the classmethod create_json_dict:
            list_items.append(UserHostsTableInfo.create_json_dict(
                id=str(user_host.id),
                ip=str(ip.address),
                mac=ip.interface.mac,
                switch=switches,
                port=ports,
                action=foo
                **rest,
            ))
    return jsonify(items=list_items)

# the template needs to get the url + cols:
# url_for(info.url), info.cols

# the json endpoint wants to generate something strictly following
# this scheme.  This means: a valid list of dicts having some columns.
# should the json view do the work?  yeah, that isn't so bad.  Perhaps
# we can move it to lib tho.  couldn't we abstract this into a
# higher-level lib function plus something accessing the cols dict?
# or better: can't we extract the cols from the function (coming from
# an object) creating said json content?

class UserTableInfoExtractor:
    def create_one_entry(self, ip):
        return {'ip': ip}
    
    @property
    def cols(self):
        return self.create_one_entry(MagicMock()).keys()
        
# or with a namedtuple:

class UserTableInfoExtractor:
    _info = namedtuple('UserHostTableInfo', ['ip'])
    
    def create_one_entry(self, *a, **kw):
        return self._info(*a, **kw)._asdict()

    @property
    def cols(self):
        return self._info._fields

# perhaps, we don't need the entry creation after all, and directly
# use the namedtuple

# or, even better, we implement __call__() and just call
# `EserTableInfo` (naming it `extractor` doesn't really make sense)
@bp.route("/<int:user_id>/hosts")
def user_show_hosts_json(user_id):
    list_items = []
    for user_host in User.q.get(user_id).user_hosts:
        # …
        for ip in user_host.ips:
            list_items.append(UserTableInfo(
                id=str(user_host.id),
                ip=str(ip.address),
                mac=ip.interface.mac,
                switch=switches,
                port=ports,
                action=foo
            ))
    return jsonify(items=list_items)

# however, directly using the namedtuple is better for the linter.