Flask-Jerify

"JSON Verify". Easy validation against JSON schemas for Flask APIs.

Leverages jsonschema.

Installation

pip install flask-jerify

Usage

Loading JSON Schemas

flask-jerify will by default look for a ./schemas directory in the running directory and read all .schema.json files:

.
├── app.py
└── schemas
    └── test-schame.schema.json

The sample test.schema.json demands a compulsory target parameter and doesn't accept any additional parameters:

{
    "title": "test schema",
    "type": "object",
    "properties": {
        "target": {
            "type": "string"
        }
    },
    "required": [
      "target"
    ],
    "additionalProperties": false
}

The schema can then be accessed with the file prefix, ie: test-schame within Jerify.

Validate Requests and JSON Error Responses

The following snippet sets up an app with jerify's custom error handler, instantiates Jerify, and sets up a route that accepts JSON conforming to the defined test-schema.schema.json JSON schema.

from flask_jerify import Jerify, jerror_handler
from werkzeug.exceptions import default_exceptions

app = Flask(__name__)

for code in default_exceptions:
    app.errorhandler(code)(jerror_handler)

jerify = Jerify(app)

@app.route('/test', methods=['POST'])
@jerify.request('test-schema')
def test():
    return '{"validated": "true"}', 200

Invalid JSON

$ curl -d '{"target":' -H "Content-Type: application/json" -X POST http://localhost:5000/test
{
  "errors": [
    {
      "code": 400, 
      "detail": "Invalid JSON", 
      "status": "Bad Request"
    }
  ]
}

Invalid Requests

$ curl -d '{"hello":"world"}' -H "Content-Type: application/json" -X POST http://localhost:5000/test
{
  "errors": [
    {
      "code": 400, 
      "detail": "'target' is a required property", 
      "status": "Bad Request"
    }
  ]
}

$ curl -d '{"target": "test", "hello":"world"}' -H "Content-Type: application/json" -X POST http://localhost:5000/test
{
  "errors": [
    {
      "code": 400, 
      "detail": "Additional properties are not allowed ('hello' was unexpected)", 
      "status": "Bad Request"
    }
  ]
}

Validate Responses

@app.route('/test', methods=['POST'])
def test():
    return jerify.validate({'hello': 'world'}, 'test-schema'), 200

$ curl -d '{"target": "test"}' -H "Content-Type: application/json" -X POST http://localhost:5000/test
{
  "errors": [
    {
      "code": 500, 
      "detail": "The server encountered an internal error and was unable to complete your request.  Either the server is overloaded or there is an error in the application.", 
      "status": "Internal Server Error"
    }
  ]
}

[2017-08-26 02:36:05 +0000] [11857] [INFO] [flask_jerify.flask_jerify] JSON failed validation against schema'test': {'target': 'test', 'hello': 'world'}

Configuration

Schemas Directory

JERIFY_SCHEMAS=./schemas

Jerify Log Level

JERIFY_LOG=WARNING