DatabaseManager

DatabaseManager is a Python package for managing MongoDB connections with pymongo. It is designed to be predictable: importing and instantiating do not open files or connect to the database. Configuration and connections are created only when you call a database method.

Behavior (No Surprises)

• Importing the package does not read config files or open connections.
• Instantiating DatabaseManager does not read config files or open connections.
• Configuration and MongoDB connections are created only when you call get_db, get_collection, or list_collections.

Features

• Lazy config loading and lazy connection setup.
• Singleton instance with thread-safe initialization.
• Auto-discovery of config.py with a Config class.
• Optional Config object with file and environment variable support.
• Database caching for repeated access.
• Clear error handling for missing config or connection failures.

Requirements

• Python 3.7+
• pymongo>=3.11

Installation

pip install git+https://github.com/botsarefuture/DatabaseManager.git

Usage

Option A: Auto-discovered config.py

Create a config.py in your project directory (the same directory as your app entry point). The DatabaseManager will load it only when the first database operation is called.

# config.py
class Config:
    MONGO_URI = "mongodb://localhost:27017"
    MONGO_DBNAME = "my_database"

from DatabaseManager import DatabaseManager

db_manager = DatabaseManager.get_instance()
db = db_manager.get_db()

If config.py is missing when a DB call happens, a FileNotFoundError is raised.

Option B: Provide a Config object

from DatabaseManager import Config, DatabaseManager

config = Config()
config.MONGO_URI = "mongodb://localhost:27017"
config.MONGO_DBNAME = "custom_database"

db_manager = DatabaseManager.get_instance(config)
db = db_manager.get_db()

Load config from a JSON/YAML/INI file

from DatabaseManager import Config, DatabaseManager

config = Config(config_file="path/to/config.json", config_type="json")
db_manager = DatabaseManager.get_instance(config)
db = db_manager.get_db()

Collections

collection = db_manager.get_collection("users")
document = collection.find_one({"name": "Ada"})

Legacy support

db = DatabaseManager.legacy_get_db()

Environment Variables

Config reads environment variables by default:

export MONGO_URI="mongodb://localhost:27017"
export MONGO_DBNAME="my_database"

Error Handling

try:
    db_manager = DatabaseManager.get_instance()
    db = db_manager.get_db()
except RuntimeError as exc:
    print(f"Error: {exc}")

Running Tests

python -m unittest -v DatabaseManager/tests/test_databaseManager.py

Directory Structure

DatabaseManager/
├── DatabaseManager/
│   ├── __init__.py
│   ├── databaseManager.py
│   ├── config.py
│   └── tests/
│       └── test_databaseManager.py
├── README.md
└── setup.py

License

MIT