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https://github.com/guoquan/contextproxy
`contextproxy` provides context-based lazy-loaded proxy objects for flask apps
https://github.com/guoquan/contextproxy
flask
Last synced: 7 days ago
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`contextproxy` provides context-based lazy-loaded proxy objects for flask apps
- Host: GitHub
- URL: https://github.com/guoquan/contextproxy
- Owner: guoquan
- License: mit
- Created: 2024-09-19T05:30:48.000Z (4 months ago)
- Default Branch: main
- Last Pushed: 2024-09-20T16:24:11.000Z (4 months ago)
- Last Synced: 2024-12-17T04:25:31.991Z (22 days ago)
- Topics: flask
- Language: Python
- Homepage: https://github.com/guoquan/contextproxy
- Size: 25.4 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Flask Context Proxy
`contextproxy` is a `@contextmanager` style `LocalProxy`, managed by `flask.g`, designed to simplify the management of lazily loaded, context-based resources in `Flask` applications. It allows resources to be easily accessed, automatically initialized and cleaned up based on `Flask`'s request and application lifecycle, and can be used to share resources across multiple requests or manage them on a per-request basis.
[](https://github.com/guoquan/contextproxy/actions/workflows/release.yml)
[](https://pypi.org/project/contextproxy/)
[](LICENSE)
## Features
- **Easy Access**: Resources can be accessed using decorated names, making them easy to use in your application.
- **Lazy Initialization**: Resources are only initialized when accessed, saving computation and memory for unused resources.
- **Automatic Teardown**: Resources are cleaned up automatically after the application context is torn down.
- **Supports `Flask` Contexts**: The decorator works seamlessly with `Flask`'s request and application contexts, ensuring context isolation and cleanup.
- **Thread Safety**: Ensures that resources are unique per thread in multi-threaded environments.
## Installation
You can install `contextproxy` by including the file in your project directory or packaging it as a Python module.
```bash
pip install .
```
## Usage
To use `contextproxy`, simply apply it as a decorator to a generator function that yields the resource you want to manage. The resource will be lazily initialized and binded to `flask.g` for the duration of the application context.
It should be noted that the resource is finalized only after the application context ends (for `Flask>=0.9`). That means the resource will be shared across multiple requests within the same application context.
### Basic Example
```python
from flask import Flask
from contextproxy import contextproxy
app = Flask(__name__)
@contextproxy(app)
def resource():
# Initialize the resource
resource_value = "This is a shared resource"
yield resource_value
# Teardown logic (e.g., closing connections) goes here
print("Resource has been cleaned up")
@app.route('/')
def index():
return f"Resource: {resource}"
if __name__ == "__main__":
app.run(debug=True)
```
In the example above, the `resource` is lazily initialized the first time it's accessed and will be automatically cleaned up after the application context ends.
## Advanced Usage
### Handling Exceptions in Resource Initialization
If your resource initialization involves risky operations (like database connections), you can handle exceptions cleanly within the resource function.
```python
@contextproxy(app)
def risky_resource():
uuid = uuid4()
print(f"before: Preparing to create resource ({uuid})")
try:
print(f"yielding: Creating resource ({uuid})")
yield f"resource {uuid=}"
print(f"yielded: where is this? ({uuid})")
except Exception as e:
print(f"except: error processing resource ({uuid}): {type(e)}: {e}")
else:
print(f"else: okey processing resource ({uuid})")
finally:
print(f"finally: Destroying resource ({uuid})")
print(f"after: Destroyed resource ({uuid})")
```
## **Contributing**
If you’d like to contribute to `contextproxy`, feel free to fork the repository, submit issues, or open a pull request!
## **License**
This project is licensed under the MIT License.