Goal

• To make REST API server for IoT
• To interface with Redis

Intro

Practice

1. Make Django Project

1.1. Install django

$ pip install django

1.2. Create Django project

• Avoid reserved word as project’s name. eg. _django, _test
• And then, new directory’ll be created and some files for Django Framework are also created.

$ cd [WORKSPACE]
$ django-admin.py startproject [PROJECT_NAME]

djago-admin.py : Django’s command-line utility for administrative tasks

1.3. Proejct directory structure

[PROJECT]
|-- [PROJECT_NAME_DIR]
|   |-- __init__.py
|   |-- settings.py
|   |-- urls.py
|   |-- wsgi.py
|-- manage.py

• manage.py
  • Django’s command-line utility for administrative tasks
  • It is same thing as django-admin
  • It can set the DJANGO_SETTINGS_MODULE environment variable so that it points to your project’s settings.py file
  • Generally, when working on a single Django project, it’s easier to use manage.py than django-admin
• [PROJECT_NAME_DIR]
  • Python packages are stored in this directory.
  • You can import Python package by using this name
  • e.g. import [PROJECT_NAME_DIR].urls
• [PROJECT_NAME_DIR]/__init.py__.py
  • It is just empty file to announce parent directory is package.
• [PROJECT_NAME_DIR]/settings.py
  • Settings/configuration for this Django project.
• [PROJECT_NAME_DIR]/urls.py
  • The URL declarations for this Django project
  • It is similar to a “table of contents” of Django.
• [PROJECT_NAME_DIR]/wsgi.py
  • An entry-point for WSGI-compatible web servers to serve your project.

  WSGI(Web Server Gateway Interface)

  HTTP Request -> Web Server -> WSGI Server(Middleware) -> Web Application(Such as Django, flask)

2. Import project in PyCharm IDE

2.1. Open Project

• Execute PyCHarm IDE and click open button

2.2 Choose the Django project

3. Run application

3.1. Edit run configuration

• Menu > Run > Run

• Edit configurations

• Add new run configuration

• Setup configuration
  • Script path : Input path of manage.py file in Django project
  • Parameters : Input ‘runserver’

  runserver host:port e.g. runserver 0:8080 (0.0.0.0:8080)

3.2. Run

• Run application

• Check whether application start up or not

4. Install Module

• Install redis and django-redis

(env) $ pip install redis
(env) $ pip install django-redis

5. Make REST API app for getting Redis data

5.1. Create app

(env) $ manage.py startapp [APP_NAME]

5.2. Create view in app

• New > Python File > view.py

• iot/view.py

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import redis from django.http import HttpResponse ############################################################ # # Request for sensors # ############################################################ # Version Date Author Description ############################################################ # 1.0.0 2019-05-28 dorbae Initialize ############################################################ # Redis Connection Pool # db : db number (default : 0) REDIS_CONNECTION_POOL = redis.ConnectionPool(host='${REDIS_HOST}', port=6379, db=1, decode_responses=False, password='${REDIS_PASSWORD}, max_connections=5) # Method for getting the information of devices in specific group def get(request, group_id): print('[DEBUG] Search ' + group_id + '...') # Connect Redis through connect pool _redisClient = redis.Redis(connection_pool=REDIS_CONNECTION_POOL) # Set client name _redisClient.client_setname('iot.rest.api') # Get values matched with group_id _keys = _redisClient.keys(group_id + '|*') # Concat str result (likes csv) _result = '' for k in _keys: v = _redisClient.get(k) _result = _result + v.decode(encoding='utf-8') # return HTTP Response return HttpResponse(_result)

5.3. Create url in app

• New > Python File > urls.py

• iot/urls.py

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from django.urls import path from . import views urlpatterns = [ path('<str:group_id>/', views.get, name='get'), ]

5.4. Edit [PROJECT]/urls.py and register [APP]/urls.py

• iotapisvr/urls.py

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from django.contrib import admin from django.urls import path, include urlpatterns = [ path('admin/', admin.site.urls), path('sensors/', include('iot.urls')), ]

6. Run and test

1	$ RESP_BODY=$(curl -G [URL]); echo $RESP_BODY

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References

• Django Tutorial

• DJango djang-admin and manage.py

• bono’s blog