import logging
from happi import Client
from happi.errors import SearchError
from happi.loader import from_container
from pydm.data_plugins.plugin import PyDMConnection, PyDMPlugin
from qtpy import QtCore
class HappiClientState:
client = None
logger = logging.getLogger(__name__)
[docs]def register_client(client):
"""
Register a Happi Client to be used with the DataPlugin.
This is not required to be called by the user, if your environment is setup
such that :meth:`happi.Client.from_config` will return the desired client.
"""
HappiClientState.client = client
[docs]class HappiConnection(PyDMConnection):
"""A PyDMConnection to the Happi Database."""
tx = QtCore.Signal(dict)
def __init__(self, channel, address, protocol=None, parent=None):
super().__init__(channel, address, protocol=protocol, parent=parent)
self.add_listener(channel)
[docs] def add_listener(self, channel):
"""Add a new channel to the existing connection."""
super().add_listener(channel)
# Connect our channel to the signal
self.tx.connect(channel.tx_slot, QtCore.Qt.QueuedConnection)
logger.debug("Loading %r from happi Client", channel)
if '.' in self.address:
device, child = self.address.split('.', 1)
else:
device, child = self.address, None
# Load the device from the Client
md = HappiClientState.client.find_item(name=device)
obj = from_container(md)
md = md.post()
# If we have a child grab it
if child:
logger.debug("Retrieving child %r from %r",
child, obj.name)
obj = getattr(obj, child)
md = {'name': obj.name}
# Send the device and metdata to all of our subscribers
self.tx.emit({'obj': obj, 'md': md})
[docs] def remove_listener(self, channel, destroying=False, **kwargs):
"""Remove a channel from the database connection."""
super().remove_listener(channel, destroying=destroying, **kwargs)
if not destroying:
self.tx.disconnect(channel.tx_slot)
[docs]class HappiPlugin(PyDMPlugin):
protocol = 'happi'
connection_class = HappiConnection
def add_connection(self, channel):
# If we haven't made a Client by the time we need the Plugin. Try
# and load one from configuration file
if not HappiClientState.client:
register_client(Client.from_config())
try:
super().add_connection(channel)
except SearchError:
logger.error("Unable to find device for %r in happi database.",
channel)
except AttributeError as exc:
logger.exception("Invalid attribute %r for address %r",
exc, channel.address)
except Exception:
logger.exception("Unable to load %r from happi", channel.address)