Setup Django WorkFlow Application

Introduction

Recently, I studied how to setup a work flow program using python django. Believe me, Python Diango can provide you a high quality work flow web application. Let’s say I would like a simple workflow application as below diagram. I will show you how to setup the application as below instruction, and I will also show you the screen dump examples of running the application.

django-workflow0

Step 1. Prerequisition

This Work Flow Program requires Python 3.3 or greater, and django 1.6 or 1.7. I recommend you to setup under virtual environment. Setup the following python plug-in by running the following command:

$ pip3 install Django==1.7.1
$ pip3 install WebOb==1.4
$ pip3 install WebTest==2.0.16
$ pip3 install amqp==1.4.6
$ pip3 install anyjson==0.3.3
$ pip3 install beautifulsoup4==4.3.2
$ pip3 install billiard==3.3.0.18
$ pip3 install celery==3.1.16
$ pip3 install django-fsm==2.2.0
$ pip3 install django-viewflow==0.7.0
$ pip3 install django-webtest==1.7.7
$ pip3 install kombu==3.0.23
$ pip3 install mock==1.0.1
$ pip3 install pytz==2014.9
$ pip3 install singledispatch==3.4.0.3
$ pip3 install six==1.8.0
$ pip3 install waitress==0.8.9

Step 2. Create a standard django project and application

Run the following command:

$ django-admin.py startproject demo .

$ ./manage.py startapp helloworld

$ mv helloworld/ demo/

Step 3. Edit or Create the following files

3.1 edit demo/settings.py

INSTALLED_APPS = (
    ‘django.contrib.admin’,
    ‘django.contrib.auth’,
    ‘django.contrib.contenttypes’,
    ‘django.contrib.sessions’,
    ‘django.contrib.messages’,
    ‘django.contrib.staticfiles’,
    ‘viewflow’,
    ‘demo.helloworld’
)

TEMPLATE_CONTEXT_PROCESSORS = (
    ‘django.contrib.auth.context_processors.auth’,
    ‘django.core.context_processors.request’,
)

3.2 edit demo/urls.py

from django.conf.urls import patterns, include, url
from django.contrib import admin
from viewflow import views as viewflow
from .helloworld.flows import HelloWorldFlow

urlpatterns = patterns(
    ”,
    url(r’^helloworld/’,
        include([
            HelloWorldFlow.instance.urls,
            url(‘^$’, viewflow.ProcessListView.as_view(), name=’index’),
            url(‘^tasks/$’, viewflow.TaskListView.as_view(), name=’tasks’),
            url(‘^queue/$’, viewflow.QueueListView.as_view(), name=’queue’),
            url(‘^details/(?P<process_pk>\d+)/$’,
                viewflow.ProcessDetailView.as_view(), name=’details’)],
                namespace=HelloWorldFlow.instance.namespace),
            {‘flow_cls': HelloWorldFlow}),
    #url(r’^flows/’, include(viewflow.urls)),
    url(r’^admin/’, include(admin.site.urls)),
    url(r’^accounts/login/$’, ‘django.contrib.auth.views.login’, name=’login’),
    url(r’^accounts/logout/$’, ‘django.contrib.auth.views.logout’, name=’logout’),
)

3.3 create demo/celery.py

import os
from celery import Celery

from django.conf import settings

os.environ.setdefault(‘DJANGO_SETTINGS_MODULE’, ‘demo.settings’)

app = Celery(‘tests’)

app.config_from_object(‘django.conf:settings’)
app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

3.4 create demo/helloworld/flows.py

from viewflow import flow
from viewflow.base import Flow, this
from viewflow.contrib import celery

from . import models, views, tasks

class HelloWorldFlow(Flow):
    process_cls = models.HelloWorldProcess

    start = flow.Start(views.CreateRequestView) \
        .Next(this.approve)

    approve = flow.View(views.ApproveRequestView) \
        .Next(this.is_approved)

    is_approved = flow.If(lambda p: p.approved) \
        .OnTrue(this.send)\
        .OnFalse(this.end)

    send = celery.Job(tasks.send) \
        .Next(this.end)

    end = flow.End()

3.5 edit demo/helloworld/models.py

from django.db import models
from viewflow.models import Process

class HelloWorldProcess(Process):
    text = models.CharField(max_length=250)
    approved = models.BooleanField(default=False)

3.6 edit demo/helloworld/tasks.py

from demo.celery import app as celery_app
from viewflow.flow import flow_job

@celery_app.task()
@flow_job()
def send(activation):
    print(activation.process.text)

3.7 edit demo/helloworld/views.py

from django.views import generic
from viewflow import views as flow_views

class CreateRequestView(flow_views.StartViewMixin,
                        generic.UpdateView):
    fields = [“text”]

    def get_object(self):
        return self.activation.process

class ApproveRequestView(flow_views.TaskViewMixin,
                         generic.UpdateView):
    fields = [“approved”]

    def get_object(self):
        return self.activation.process

Step 4. Start the Application Server

Run the following Command:

./manage.py createsuperuser –username=admin –email=admin@admin.com
( setup admin password )

./manage.py makemigrations

./manage.py migrate

Start the following celery in another virtual env

celery -A demo worker -l info

Start the application server:

./manage.py runserver

Step 4. Run the Application from browser

Admin Logon

http://127.0.0.1:8000/admin/

WorkFlow Application Logon

http://127.0.0.1:8000/helloworld/

Step 5. Screen Dump Example of running the WorkFlow Application

django-workflow1

django-workflow2

django-workflow3
django-workflow4
django-workflow5

Reference Document Link:

http://viewflow.io/

http://docs.viewflow.io/material_admin.html

https://pypi.python.org/pypi/django-viewflow

Setup a Survey Web Site with Python & Django

Introduction

This document shows how to setup a survey web site using python 2.7 and django 1.4. We do not need to use web server software such as IIS or Apache while python can start web server service itself. This survey web site can run under window and linux env provide that it has python. I will show its setup steps as below.

Step 1.

Download the program source code “django-survey-master.zip” from web site https://github.com/jessykate/djngo-survey and unzip it to a computer with python 2.7.

Step 2.

Under the django-survey-master directory, run the command $ pip install -r requirements.txt to install django.

Step 3.

Setup the survey database as command $ python manage.py syncdb , which you need to input a username and password.

Step 4.

Start the survey server as command $ python manage.py runserver ,as below screen dump:

survey1

Step 5.

Setup a survey as below screen dump with link http://127.0.0.1:8000/admin :

survey3

survey4

Step 6.

Browse the survey web site to fill-in a survey as below link http://127.0.0.1:8000 :

survey2

survey5

Bonus of a problem solving

Problem 1: The Survey web site is with link localhost:8000 and 127.0.0.1:8000 in its computer and that works fine. However, it cannot be accessed from other computer in the same network.

Solution 1: Start the Web Site Server with its own ip address, such as $ python manage.py runserver 192.168.5.105:8000; then other computers in the same network can access it with link http://192.168.5.105:8000.

Problem 2: If you have problem of running http://127.0.0.1:8000/admin, it comes out a error message “Admin Site: TemplateDoesNotExist at /admin/ …”

Solution 2: Force to re-download django with command:

pip install -r requirements.txt --ignore-installed --force-reinstall --upgrade --no-cache-dir

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