Ultimator14/mini_pos

Small browser based POS system

Mini POS

General

This is a simple POS system built to simplify the act of serving food/drinks.

Traditional service

The usual procedure for this would be that a waiter

• Walks around
• Takes an order
• Walks to the kitchen
• Passes the order
• Waits while it's prepared
• Takes the food/drinks
• Walks to the client
• Delivers the food/drinks
• Cashes up

Improved service

Using this system, the ordering procedure would be

A waiter

• Walks around
• Takes an order with his smartphone
• Cashes up

The order is automatically received in the kitchen

Another waiter

• Takes food/drinks
• Walks to the client
• Delivers the food/drinks

In contrast to the traditional service, the delay between ordering and passing the order the the kitchen as well as unnecessary waiting has been eliminated completely.

Setup

• The software does not require an internet connection an can be run on e.g. a raspberry pi
• Both kitchen and waiter need have access to the server via network (e.g. by using a hotspot or a connecting everything to a router)
• The server can be started with gunicorn --bind 0.0.0.0:80 run:app
• Waiters can connect to the server with their smartphones via http://<ip>/service
• The kitchen can connect to the server with a desktop computer via http://<ip>/bar

Requirements

• A desktop computer or tablet with large screen for the kitchen
• A smartphone for each cashier with a browser installed
• A device where the server can run on (can be the same as for the kitchen) with >=python3.10 installed
• Some kind of network to connect everything

Usage

Install

Clone the repository:

git clone https://github.com/Ultimator14/mini_pos.git
cd mini_pos

Install dependencies:

poetry install

Enter the poetry virtual environment:

poetry shell

Run

Development (Werkzeug server):

python run.py

Production (Gunicorn server):

sudo sysctl -w net.ipv4.ip_unprivileged_port_start=80    # allow binding to port 80 without root
gunicorn --bind 0.0.0.0:80 --workers=4 run:app      # run the app
sudo sysctl -w net.ipv4.ip_unprivileged_port_start=1024  # reset sysctl config change

Configuration

Configuration is done in the config.json file. The file is mandatory. The software does not start without it.
Some configuration options are

Config option	Description	Format
product/available	List of available products (name, price, category)	List[str Name, float price, int category]
product/categories	Category names	List[int category, str name]
table/size	Size for the table grid in service	int x, int y
table/names	Table positions, sizes and names	List[int x, int y, int xlen, int ylen, str name]
ui/auto_close	Automatically complete an order when all products are marked as completed	bool true/false
ui/show_completed	Show the last n completed orders in /bar	int n
ui/show_category_names	Show category names between products of different category in service	bool true/false
ui/fold_categories	Fold categories by default in service	bool true/false
ui/timeout	Timeout in seconds to mark orders yellow/red	int timeout_warn, int timeout_crit

Categories

An additional space is added between adjacent products with different category in service. If show_category_names is enabled, the space is filled with the corresponding category name.

Categories 0-14 have a distinct color scheme

• Products in category 1-7 have a light colored background per default and become heavily colored upon selection. The category separators are not colored
• Products in category 8-14 have a white background per default and become light colored upon selection. The category separators are colored heavily
• All other products have a white background per default and are colored green upon selection. The category separators are not colored

Colors can be added or edited directly in service_table.css

Tables

Table positions can be customized. Tables must have a start position x,y, a horizontal and vertical length xlen, ylen and a name.
Overlapping tables are not supported and will produce a warning.
Tables outside the grid are not supported and will produce an error.

Pitfalls

It's not safe to alter configuration options and restarting the server without reloading the pages on the client side.
Make sure, that waiters reload the page after a config change and server restart happened.

Example:

Removing, adding or swapping products in the configuration could cause a wrong product to be ordered when the server is restarted.
Products are numbered by their position in the configuration file. When a table is opened in service, the product numbers are fetched from the server. When the server is restarted and the product numbers changed somehow, frontend and backend are not synced anymore. This could cause wrong products in the next order.

Scenario:

• Waiter opens /service/A1, products are Prod1 (1), Prod2 (2), Prod3 (3)
• Product Prod1 is removed from server config
• Server is restarted
• Products in server are now Prod2 (1), Prod3 (2)
• Waiter orders Prod2 identified by number 2
• Server receives number 2 and maps it to product Prod3

Images

Bar

Service

Analysis

The analysis script provides an overview about sold products, revenue as well as some more statistics.
For the script to work, the dependencies from the analysis group must be installed. Afterwards the analysis can be started with the analyze.py script. The results are saved as analysis.pdf.

Install analysis dependencies:

poetry install --with analysis

Enter the poetry virtual environment:

poetry shell

Start analysis:

python analyze.py

Note: When it's desired to show the plots in a window, uncomment the last line plt.show() in the analyze.py script.
However the command plot.show() will probably not work. This is because PyQt5 is not included in the dependency list. Which again is because poetry is cross-platform but PyQt5 only supports some specific architectures. To still be able to show plots inside the poetry virtualenv, use pip install pyqt5 (if there exists a wheel for your arch). Alternatively install PyQt5 on your system and use the virtualenvs.options.system-site-packages config option for poetry to allow the virtualenv to access it.