Lagring 0.2.7.1

Asset storage for Flask

# Lagring: asset storage for Flask


## Requirements

- SQLAlchemy
- Flask
- PostgreSQL 9.4+

## Installation

pip install lagring

If you want to use `ImageAsset` class you have to install Pillow as well.

## How to use it

0. Configure your Flask app to have necessary config options:

Parameter | Meaning
-------------------|--------------------------------------------------
ASSET_STORAGE_ROOT | Path to the directory where assets will be stored
ASSET_URL_ROOT | Asset URL invariable part

1. Create storage instance:

```python
from lagring import FlaskLagring

storage = FlaskLagring()
storage.init_app(app)
```

2. Derive your SQLAlchemy model from `storage.Entity` class:

```python
from lagring import Asset

class File(db.Model, storage.Entity):
id = db.Column(db.Integer, primary_key=True)
file = Asset()
```

Note that JSONB field `_assets` will be added to the model (PostgreSQL 9.4+).
You can change the name by overriding `lagring.Entity.asset_data_field` method.

3. Put something to that asset field:

```python
new_file = File()
db.session.add(new_file)
db.session.flush()
new_file.file = '/some/local/path/filename'
db.session.commit()
```

The model instance must have a valid id on asset assignment, so you have to call `flush()`
before that.

4. Then you can use the asset like this:

```python
# get asset URL
url = new_file.file.url
# get asset path
path = new_file.file.abs_path
# delete the asset
del new_file.file
```

5. Besides the basic `Asset` class, there are also `ImageAsset` and `DirectoryAsset` to store
something more specific and have some processing on upload (no docs for that yet, please see
the code).