This is probably stupid question but I can't really grasp what I should do. I'd like to because I'm currently tasked to create something like order system, which could benefit from this, but I don't know where to start.
The really short version of "use statemachine" is: store a single, explicit state for every 'thing' and create a log row every time that state changes.
- Make a python model / database table to represent "the things whose state can change" (like an Order or a Task).
- Give each a unique id and a 'state' column that is either a text field or an enumerated type (or a foreign key to a 'valid_states' table if you want to get fancy). Do this _instead_ of adding boolean columns like 'is_completed' or 'is_deleted'.
- Create a log table with the same columns as your Order table -- whenever you update an Order's state (or create a new one), add a new row to the log table with the new state and a timestamp. Now your 'Order' table shows the current state of every Order, while your log table shows every state that every Order has ever been in, which will come in _super_ handy for analytics later.
Everything else can be built on top of the above:
- defining valid states and their transitions (aka formalizing the state machine)
- preventing 'invalid' transitions if you want
- creating analytics tables to show the 'typical' flow of an Order (e.g. columns like 'creation_date', 'payment_date', 'ship_date', 'return_date')
- triggering other systems when Orders enter or leave a given state - etc
There might be libraries to encapsulate the mechanics of state machines -- I don't know, though, because I find the mechanics of creating them easy enough that I never felt the need to seek out a library to support them.
I'd recommend reading up about them on the web. Here's a reasonable start: https://www.freecodecamp.org/news/state-machines-basics-of-c...
In their purest form, though, state machines are very simple. You have a conceptual "state" represented by a variable, then what amounts to a series of if-then statements (or a switch statement like in C/C++). The state machine consists of a loop, each iteration checking the current state (1, 2, 3, etc.) and performing the actions associated with that state. Then the state is changed as appropriate and the loop continues.
So you have something like "If the state is "Starting", then do initialization things and change the state variable to "Running". If the state is "Running", do some business logic. If it's time to quit, change the state to "Stopping". If the state is "Stopping", free up resources and stop execution."