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Developer's Guide for GNUKhata Web Front-end

Welcome to this guide on programming GNUKhata front end. As you are aware, GNUKhata is a core set of APIs containing all the business logic for book keeping, inventory and generating related reports. As a result, programmers can write different type of front-ends by utilizing the same core logic. This is a web app, i.e the web based front-end. We are very happy to help you help us and the free software community for creating this free,(as in freedom ) professional quality and industry level accounting software. To participate in the development of this web front end, you should first fulfill the prerequisites. This will save your time and avoid any confusion on getting started or on certain aspect of the development/ programming. Note that you can always join the GNUKhata developers mailing list and discuss with us any difficulty or suggestion you have.

Requirements

GNUKhata uses Python programming language for both it's core logic and the web based front-end. In addition, you will need to be aware of concepts needed to write a web based application. Here is a list of prerequisites along with brief description.

GNU/Linux OS

Needless to say we exclusively use GNU/Linux operating system for our daily work and professional programming. We are free software advocates and urge every one to use it, not just for the superior, faster and professional performance but also because it is a freedom technology. GNU/Linux is the free (as in freedom ) OS and we recommend Ubuntu, Mint, or if you like the hacker stuff, Debian brands. Note that GNUKhata works on Windows but all our programming and designing happens on the said OS.

Gitlab account

One major aspect of a free and open source project is that it's source code is open and freely available to all. You can copy, study, modify and share it with any one for any purpose. However for professional management and quality assurance every project needs a core team in charge of the main source code. Any one can then make an exact copy of the original source code and make any changes to that copy. Then such changes are submitted to the main repository (meaning the code base ). a merge request can be then sent where the core team members screen the submitted code for quality and see if the said task is properly done. If all is well then the contribution is merged into the main repository. There are several such free project management and collaboration tools. One such is Git Lab and that's what we use for GNUKhata. You should make an account there and then follow the instructions in this guide for forking and cloning a copy of the source code for yourself. You can also visit Gitlab basics to get started. You may consider this as your entry into collaborative free software development in general and GNUKhata in particular.

Python

Python is a very powerful, robust, scalable programming language. But having this power, it is extremely easy to learn. You can enjoy learning this amazing programming language from this easy book

Pyramid Web Framework

Writing every component by yourself all in great details takes a lot of time. In addition if you were to write every little repeatable code and commonly used components like connectivity logic, data dynamics etc then no project can ever finish in time. Web frameworks come to our rescue here. A framework not just helps by providing skeleton code for most common tasks, but also ready to use infrastructure for connectivity database access etc. We use Pyramid web framework for both our back-end and front-end. Look at chapter 1,2,7,8,9,10,11 and 12 in particular in the book for quick understanding.

JavaScript with jQuery

Most of the user interaction on the browser including clicking, selecting text, sending and receiving data from forms and related stuff is done using a browser based programming language called JavaScript. You can get started by reading this manual
You can get comprehensive tutorials here

We use the jQuery library of JavaScript for making our work easy. You will need to learn this because most of the challenging work regarding user interaction is done using this library. you can get started with jQuery basics by reading this basic tutorial Most of the styling, layout etc is done using the Bootstrap CSS library. Read the basic tutorial to know more about it.

Installation

To install GNUKhata in development mode, there are a few things to understand. First and for most, GNUKhata core is needed for which you will be building the web app. Secondly, All dependencies related to Python based code will be installed in a virtual environment. A virtual environment isolates your own personal copy of the Python programming language, Also gives you freedom to have several copies and all this never affects the main Python setup. In addition keep in mind that the core logic needs Postgresql database and a few other things to work. As a web app developer, you may not need to know much about the core but knowing how to run it will be necessary. We will first install the dependencies, then create the virtual environment and add the necessary Python libraries, incuding the Pyramid framework. Then we clone our copy of gkcore and gkwebapp. Note that to install libraries and to run GNUKhata, the virtual environment must be first activated. Note also that steps given here should be followed completely. If any step is skipped it might result in GNUKhata not working at all or working improperly. BE CAREFULL, You ARe WARNED!

All the following set of commands should be given in a terminal. You can press alt + ctrl + t to get a terminal. you will see the $ prompt as soon as the terminal opens. Note: you have to press enter after completely typing every command. Note: the $ sign is just provided to indicate a terminal, so please don't include it in your commands.

Install python-virtualenv postgresql and dependencies using following command

$ sudo apt-get install python-virtualenv postgresql-9.5 python-dev libpq-dev git

if you are going to use Eclipse IDE then you will also need java, install it using:

$ sudo apt-get install openjdk-8-jdk

Create a python virtualenv in a directory using:

$ virtualenv gkenv

change directory to gkenv:

$ cd gkenv

Activate your virtualenv using:

source bin/activate

Install dependencies in the virtualenv using:

pip install pyramid pyramid_debugtoolbar psycopg2 odslib sqlalchemy waitress wsgicors requests monthdelta pyjwt pillow babel pycrypto openpyxl

Fork gkwebapp from https://git.fosscommunity.in/gnukhata/gkwebapp
Fork gkcore from https://git.fosscommunity.in/gnukhata/gkcore
Create and add your SSH key to gitlab by following this guide - https://git.fosscommunity.in/help/gitlab-basics/create-your-ssh-keys.md
Clone gkwebapp and gkcore in your workspace using:

git clone gitlab@git.fosscommunity.in:<username>/gkwebapp.git

git clone gitlab@git.fosscommunity.in:<username>/gkcore.git

Change directory to gkcore
Look inside the directory. You must find files like gkutil.sh, setup.py, initdb.py and gkcore.ini
Give permission to gkutil.sh file to execute and execute the same using:

chmod 755 gkutil.sh

./gkutil.sh

Activate your virtual environment and run setup.py using:

python setup.py develop

Your environment will be checked for all the required libraries and the missing ones will be downloaded.
Now we have to run initdb.py script. This will create tables in our database. To run this script we need to switch to a user 'gkadmin' which was created when we ran 'gkutil.sh' script.

sudo su gkadmin

Activate your virtualenv and then run initdb.py.

python initdb.py

To run gkcore server in development mode use:

pserve gkcore.ini

Open another terminal and change directory to gkwebapp
Activate virtualenv and run setup.py using