How to work with Models

How to work with the API; and using the Analyser, Django provides a wonderful API Note: this is used only with python manage.py shell or python manage.py shell_plus

CRUD operations

Create:

>>> Analyser.object.create() # creates an empty record

We can store this in a variable

>>> analyser = Analyser.objects.create() # our defaults be kawa, you know.
>>> analyser.save() # use the `save()` method to save the analyser

Read:

>>> Analyser.objects.all() # fetches all analysers

You can filter or pick a particular set of analysers too

>>> Analyser.objects.filter(id=1) # e.g. by id or primary key (kisumulozo)
>>> Analyser.objects.filter(pk=1)

Or search by fields or columns

>>> Analyser.objects.filter(carbonmonoxide_sensor_present=False)

How should we approach creation of readings (the long form algorithm), this is an example

# get a station
from django.shortcuts import get_object_or_404
# assumption is you are looking for a station with a pk of 1 (note this changes dynamically)
station = get_object_or_404(Station, pk=1) 

# populate readings through the Station's analyser
a_reading = station.analyser.readings.create(
				carbonmonoxide_sensor_reading = 34,
				nitrogendioxide_sensor_reading = 34,
				lpg_gas_sensor_reading = 23					
				)
# save
a_reading.save()

If you want to get readings in the future at a particular station

other_station = get_object_or_404(Station, pk=2)
# getting all readings in one line
other_station.analyser.readings.all()

# please look at the django ORM API and learn to use it.

Deploying this project

1. Cd into the project

cd Quali-Hewa/quali/

2. make a copy of localsettings.py.example

cp localsettings.py.example localsettings.py

In this case, all this is done in the quali folder.

3. Edit the localsettings.py file in production or development with your database settings such as passwords or usernames or even other database systems. In the server, you edit this with either vim or nano

4. Install project dependency

pip install -U -r requirements.txt

Reference: http://www.jeffknupp.com/blog/2013/12/18/starting-a-django-16-project-the-right-way/

Installing ReportLab on windows (binaries): http://www.lfd.uci.edu/~gohlke/pythonlibs/

5. Restart web server