python-json-database-manager

The json file database manager used in many of my projects.

A thread safe json database context manager. The class creates separate locks for each .json file in the same directory as the .py file. This way if one file is edited other files do not have to wait. There are 23 test in test_database_manager.py.

This class can be used with the with statement.

Here is some example code:

from database_manager import Database as db

db.create('test')

with db('test') as users:
    users["quinten"] = {"status": "cool"}
    users["foo"] = "bar"

The context manager will automatically fetch the data that is in the .json file and make sure this code runs in a lock specific to the file in the enter and will in the exit write the modified dictionary back to the file. If any unhanded errors happen in the with no data is written back to the file.

You can initiate the class with a target name. The class checks if this file exists. If it does then the with statement will write the dictionary to that file.

You can also change the target name by modifying self.name. There is an automatic check that will assert if this new name exists.

Static methods

There are also a couple static methods for when you do not want to run a database command in a with. All of these static methods will all acquire the lock for the file automatically.

• info() -> Gives some info about the Database like paths and current locks.
• create_backup(filenames: list[str]) -> Makes a backup of all .json files in the backup folder. The default backup location is json_db_backups. Give "all_of_them" as input to back up all files. This is the default.
• read(name) -> Will return the data in name.json
• write(name,data) -> Will write data to name.json
• add(name, data key) -> Will add/replace data under key in name.json. A shorthand for read + write.
• append(name, data) -> Will append data to a list named name in name.json
• reset_all(default_data) -> Will write default_data to all databases. You can implement your own exceptions here.
• translate(name, key) -> Will return the value for key in name.json. Usefully for 1 layer dicts.
• create(name, data) -> Will create a new name.json in the db dir, write data to it and will add a new lock. Do not create json files without this method as the database does only index json files on startup.

There are also non-static versions of these methods that end in s. These don't take a name but instead look at self.name to know which file it should interact with. .reads and .writes don't use a lock.

Finally, a __contains__ is implemented . So you can use the in keyword with an instance. A lock is used when not in a context manager and no lock is used if you are in a context manager.