flask-expects-json 1.0.0

Decorator for REST endpoints in flask. Validate JSON request data.

[](https://pypi.python.org/pypi/flask-expects-json)
[](https://pypi.python.org/pypi/flask-expects-json)
[](https://pypi.python.org/pypi/flask-expects-json)
[](https://pypi.python.org/pypi/flask-expects-json)

# flask-json-expects

Decorator for REST endpoints in flask. Validate JSON request data.

When building json REST services I find myself already specifying json-schema for POST data while defining swagger spec. This package brings json validation to flask. It omits the need to validate the data yourself while profiting from an already established standard (http://json-schema.org/). Defining the schema right before the route helps the self-documentation of an endpoint (see usage).


This package uses jsonschema to for validation: https://pypi.python.org/pypi/jsonschema

## Usage

This package provides a flask route decorator to validate json payload.

```python
from flask import Flask, jsonify, g, url_for
from flask_expects_json import expects_json
# example imports
from models import User
from orm import NotUniqueError

app = Flask(__name__)

schema = {
'type': 'object',
'properties': {
'name': {'type': 'string'},
'email': {'type': 'string'},
'password': {'type': 'string'}
},
'required': ['email', 'password']
}


@app.route('/register', methods=['POST'])
@expects_json(schema)
def register():
# if payload is invalid, request will be aborted with error code 400
# if payload is valid it is stored in g.data

# do something with your data
user = User().from_dict(g.data)
try:
user.save()
except NotUniqueError as e:
# exception path: duplicate database entry
return jsonify(dict(message=e.message)), 409

# happy path: json response
resp = jsonify(dict(auth_token=user.encode_auth_token(), user=user.to_dict()})
resp.headers['Location'] = url_for('users.get_user', user_id=user.id)
return resp, 201
```

The expected json payload is recognizable through "schema". If schema is not met the requests aborts (400) with a hinting error message.

```flask.request.get_json(force=True)``` is used to get the data. This means the mimetype of the request is ignored.

Note on self-documentation: all input and output possibilities are clearly visible in this snippet.

## Testing

```python
python setup.py test
```

For coverage use the python coverage package. See ```/cov.sh``` for usage.

```./cov.sh``` will pip install coverage. So make sure to use it in the context of your virtual env.