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from django.apps import apps
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.utils.module_loading import autodiscover_modules
class LookupChannelRegistry(object):
"""
Registry for LookupChannels activated for your django project.
This includes any installed apps that contain lookup.py modules (django 1.7+)
and any lookups that are explicitly declared in `settings.AJAX_LOOKUP_CHANNELS`
"""
_registry = {}
def load_channels(self):
"""
Called when loading the application. Cannot be called a second time,
(eg. for testing) as Django will not re-import and re-register anything.
"""
autodiscover_modules('lookups')
if hasattr(settings, 'AJAX_LOOKUP_CHANNELS'):
self.register(settings.AJAX_LOOKUP_CHANNELS)
def register(self, lookup_specs):
"""Register a set of lookup definitions.
Args:
lookup_specs (dict): One or more LookupChannel specifications
- `{'channel': LookupChannelSubclass}`
- `{'channel': ('module.of.lookups', 'MyLookupClass')}`
- `{'channel': {'model': 'MyModelToBeLookedUp', 'search_field': 'field_to_search'}}`
"""
for channel, spec in lookup_specs.items():
if spec is None: # unset
if channel in self._registry:
del self._registry[channel]
else:
self._registry[channel] = spec
def get(self, channel):
"""Find the LookupChannel class for the named channel and instantiate it.
Args:
channel (string): - name that the lookup channel was registered at
Returns:
LookupChannel
Raises:
ImproperlyConfigured - if channel is not found.
Exception - invalid lookup_spec was stored in registery
"""
from ajax_select import LookupChannel
try:
lookup_spec = self._registry[channel]
except KeyError:
raise ImproperlyConfigured(
"No ajax_select LookupChannel named %(channel)r is registered." % {'channel': channel})
if (type(lookup_spec) is type) and issubclass(lookup_spec, LookupChannel):
return lookup_spec()
# damnit python.
# ideally this would match regardless of how you imported the parent class
# but these are different classes:
# from ajax_select.lookup_channel import LookupChannel
# from ajax_select import LookupChannel
elif isinstance(lookup_spec, dict):
# 'channel' : dict(model='app.model', search_field='title' )
# generate a simple channel dynamically
return self.make_channel(lookup_spec['model'], lookup_spec['search_field'])
elif isinstance(lookup_spec, tuple):
# a tuple
# 'channel' : ('app.module','LookupClass')
# from app.module load LookupClass and instantiate
lookup_module = __import__(lookup_spec[0], {}, {}, [''])
lookup_class = getattr(lookup_module, lookup_spec[1])
return lookup_class()
else:
raise Exception("Invalid lookup spec: %s" % lookup_spec)
def is_registered(self, channel):
return channel in self._registry
def make_channel(self, app_model, arg_search_field):
"""Automatically make a LookupChannel.
Args:
app_model (str): app_name.ModelName
arg_search_field (str): the field to search against and to display in search results
Returns:
LookupChannel
"""
from ajax_select import LookupChannel
app_label, model_name = app_model.split(".")
class MadeLookupChannel(LookupChannel):
model = get_model(app_label, model_name)
search_field = arg_search_field
return MadeLookupChannel()
registry = LookupChannelRegistry()
def get_model(app_label, model_name):
"""Loads the model given an 'app_label' 'ModelName'"""
return apps.get_model(app_label, model_name)
def register(channel):
"""Decorator to register a LookupClass.
Example::
from ajax_select import LookupChannel, register
@register('agent')
class AgentLookup(LookupClass):
def get_query(self):
...
def format_item(self):
...
"""
def _wrapper(lookup_class):
if not channel:
raise ValueError('Lookup Channel must have a channel name')
registry.register({channel: lookup_class})
return lookup_class
return _wrapper
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