ConnectorDB Python Client
This is a mini-crash-course in the ConnectorDB python interface
To install:
pip install connectordbIf on ubuntu, you might want to install python-apsw before running the above command. You can look at the dependencies in setup.py.
Tutorial
Seriously, start with the tutorial. The samples below will be confusing until you are done with it!
Logging
The simplest, and most common task is logging data. Suppose we have a little weather station that gives us the temperature every minute.
def getTemperature():
#Your code here
pass
from connectordb.logger import Logger
def initlogger(l):
# This function is called when first creating the Logger, to initialize the values
# api key is needed to get access to ConnectorDB
l.apikey = raw_input("apikey:")
# If given a schema (as we have done here), addStream will create the stream if it doesn't exist
l.addStream("temperature",{"type":"number"})
# Sync with ConnectorDB once an hour (in seconds)
l.syncperiod = 60*60
# Open the logger using a cache file name (where datapoints are cached before syncing)
l = Logger("cache.db", on_create=initlogger)
# Start running syncer in background
l.start()
# While the syncer is running in the background, we are free to add data
# to the cache however we want - it will be saved first to the cache file
# so that you don't lose any data, and will be synced to the database once an hour
while True:
time.sleep(60)
l.insert("temperature",getTemperature())ConnectorDB Basics
The logger is a convenient wrapper for gathering data. When wanting to operate on the database directly, you will want to use the ConnectorDB object:
from connectordb import ConnectorDB
db = ConnectorDB("apikeysadfdsf98439g")
mystream = db["mystream"]
if not mystream.exists():
mystream.create({"type": "string"})
mystream.insert("Hello World!")
#mystream has 1 datapoint
print "mystream has",len(mystream),"datapoint"
#Prints Hello World! - each datapoint is a dict where "t" is the timestamp, and "d" is the data
print mystream[0]["d"]Subscriptions
You can subscribe to streams, so that you get data the moment it is written to the database.
from connectordb import ConnectorDB
db = ConnectorDB("apikeysadfdsf98439g")
mystream = db["mystream"]
if not mystream.exists():
mystream.create({"type": "string"})
def callbackFunction(streampath,data):
print streampath,data
mystream.subscribe(callbackFunction)
#After inserting, callbackFunction will run!
mystream.insert("Hello World!")If you are implementing a downlink stream (a stream that accepts input from other devices, such as a light switch), subscribe to the downlink:
from connectordb import ConnectorDB
import time
db = ConnectorDB("apikeysadfdsf98439g")
mystream = db["mylight"]
if not mystream.exists():
mystream.create({"type": "boolean"})
mystream.downlink = True
def callbackFunction(streampath,data):
ison = data[-1]["d"]
if ison:
turn_on_light()
else:
turn_off_light()
# This acknowledges the datapoint by writing the action that was taken to the real stream
# As a shortcut, you can also use return True to acknowledge the unmodified data
# meaning that return True would return the original data as given by the data variable.
# Not returning anything or returning False does not acknowledge the downlink.
# WARNING: Make sure only ONE callback acknowledges the downlink to avoid double-inserts
# DANGER: Make sure you only acknowledge downlinks to streams that belong to the currently
# authenticated device, since inserting as a different device will redirect to
# the downlink stream, creating an infinite insert loop.
return [{"t": time.time(),"d": ison}]
mystream.subscribe(callbackFunction,downlink=True)
while True:
time.sleep(100)Testing
Running ConnectorDB tests requires initalizing ConnectorDB in test mode:
connectordb create testdb --test
connectordb start testdb
Once ConnectorDB is running:
pip install -r requirements.txt
nosetests
