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While it does make sense to move serialization closer to the models, I'm -1 on this particular approach.  The proposal increases the repetitive code by adding yet another place we must modify when changing the model or API.  We should be heading towards something that satisfies the DRY principle.

mark

On Jan 16, 2013, at 8:57 AM, Avishay Balderman <AvishayB at radware.com> wrote:

> Background:
> When a read operation is preformed via quantum API the result of the DB query is converted into python dictionary.
> So we  have a function like this for each DB entity:
>  
>     def _make_router_dict(self, router, fields=None):
>         res = {'id': router['id'],
>                'name': router['name'],
>                'tenant_id': router['tenant_id'],
>                'admin_state_up': router['admin_state_up'],
>                'status': router['status'],
>                'external_gateway_info': None}
>         if router['gw_port_id']:
>             nw_id = router.gw_port['network_id']
>             res['external_gateway_info'] = {'network_id': nw_id}
>         return self._fields(res, fields)
>  
> A generic approach:
> The idea is to have ONE ”as_dict”  function that will get the DB object plus meta data that explains how to “dict it”.
>  
> What we gain here:
> 1.       We have the mapping of the DB objects to dicts in one central location (See  the Appendix below)
> 2.       All “_make_XYZ_dict” functions are gone and no need to write them in the future
>  
> So we created this configuration and a generic function that does the “magic”.
> We have also created 9 unit tests  that use the current quantum as_dict functions in one hand and the generic as_dict function on the other hand.
>  
> Code is here:
> https://www.dropbox.com/s/d9qx16r6ocp4veo/db2dict.py (please ignore alignment issues – the code needs cleanup)
>  
> You can actually run it – just put it under quantum/db
>  
>  
> Thanks
>  
> Avishay
>  
>  
> Appendix
>  
> MODEL_TO_API_MAP =  {
>  
>     "quantum.db.l3_db.Router":["id",
>                 "name",
>                 "tenant_id",
>                 "admin_state_up",
>                 "status",
>                 {"external_gateway_info":{"gw_port":["network_id"]}}
>                ],
>     "quantum.db.models_v2.Network":["id",
>                "name",
>                "tenant_id",
>                "admin_state_up",
>                "status",
>                "shared",
>                {"subnets":["id"]},
>                ],
>     "quantum.db.models_v2.Subnet":["id",
>               "name",
>               "tenant_id",
>               "network_id",
>               "ip_version",
>               "cidr",
>               {"allocation_pools":[{"start":"first_ip"},{"end":"last_ip"}]},
>               "gateway_ip",
>               "enable_dhcp",
>               {"dns_nameservers":["address"]},
>               {"host_routes":{"routes":["destination","nexthop"]}}, 
>               "shared",
>               "gateway_ip"
>               ],
>     "quantum.db.models_v2.Port":["id",
>             "name",
>             "tenant_id",
>             "network_id",
>             "admin_state_up",
>             "mac_address",
>             "status",
>             {"fixed_ips":["subnet_id","ip_address"]},
>             "device_id",
>             "device_owner"
>            ],
>   "quantum.db.l3_db.FloatingIP" : ["id",
>            "tenant_id",
>            "floating_ip_address",
>            "floating_network_id",
>            "router_id",
>            {"port_id":"fixed_port_id"},
>            "fixed_ip_address"
>            ],
>   "quantum.db.securitygroups_db.SecurityGroup" : ["id",
>            "tenant_id",
>            "name",
>            "description",
>            "external_id"
>            ],
>   "quantum.db.securitygroups_db.SecurityGroupRule" : ["id",
>            "tenant_id",
>            "external_id",
>            "security_group_id",
>            "ethertype",
>            "direction",
>            "protocol",
>            "port_range_min",
>            "port_range_max",
>            "source_ip_prefix",
>            "source_group_id" 
>            ]
>  
> }
>  
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