[JAVA] Create a simple API just to input and output JSON files ~ Python / Flask edition ~

(* Since the edit request was merged, the code has changed significantly. There is no change in the function.)

Purpose

Quickly create an API that allows you to easily read and write JSON from the client.

What to do in this article

--Use Python2.7 / Flask. --Generate / read / write JSON file instead of DB.

What not to do in this article

--Python environment construction. --Detailed code explanation.

background

I want to change the UI depending on the state of the content, the state of the user, etc. I wanted a JSON that returns the state so that I can add / change the screen state and parameters while making a client (around the Web), so I made a simple one. It's as simple as running it in your local environment. (It is assumed that a dedicated application server will be used in the production environment.)

API

It is an API that treats JSON like KVS, with the JSON file name as key and the data to be retrieved (JSON) as value. Locally use Flask to launch http://127.0.0.1:5000 and interact with it.

Get values (JSON) by specifying key

Used to get <key> .json.

$ curl http://127.0.0.1:5000/api/<key> -X GET

$.ajax({
  type: 'GET'
  url:'http://127.0.0.1:5000/api/<key>'
}).done(function(res){
  //Processing after GET
});

Add or update values (JSON) with key

It is used to register (or overwrite), for example, {" status ": 0} in <key> .json.

$ curl http://127.0.0.1:5000/api/<key> -X POST\
  --data '{"status": 0}' -H "Content-type: application/json"

$.ajax({
  type: 'POST',
  url:'http://127.0.0.1:5000/api/<key>',
  data: '{"status": 0}',
  headers: {
    'Content-Type': 'application/json'
  }
}).done(function(res){
  //Processing after POST
});

Delete the parameter (json_key) in the values (JSON) associated with the key

If <key> .json contains, for example,{"<json_key>": <arbitrary value>}, remove the<json_key>element from <key> .json.

$ curl http://127.0.0.1:5000/api/<key>/<json_key> -X DELETE

$.ajax({
  type: 'DELETE',
  url:'http://127.0.0.1:5000/api/<key>/<json_key>'
}).done(function(res){
  //Processing after DELETE
});

wrote

First of all, I made it as small as possible.

• Note that there are side effects when writing.

API implementation part

api.py

# -*- coding: utf-8 -*-

import json

from flask import Flask, request, jsonify


app = Flask(__name__)


"""Routing:Calls the process according to the request URI and method and returns the result."""
@app.route('/', methods=['GET'])
def hello():
    return 'hello:)'


@app.route('/api/<key>', methods=['GET'])
def get(key):
    model = get_model(key)
    if model is None:
        return "NOT FOUND"
    else:
        return jsonify(model)


@app.route('/api/<key>', methods=['POST'])
def post(key):
    result = set_property(key, json.loads(request.data))
    return jsonify(result)


@app.route('/api/<key>/<property_name>', methods=['DELETE'])
def delete(key, property_name):
    result = delete_property(key, property_name)
    if result is None:
        return "NOT FOUND"
    else:
        return jsonify(result)


"""Manipulation on the model"""
def get_model(key):
    return read_model(key)


def set_property(key, properties):
    data = read_model(key)
    if data is None:
        data = {}
    data.update(properties)
    result = write_model(key, data)
    return result


def delete_property(key, property_name):
    data = read_model(key)
    if data is None:
        return None
    if property_name not in data:
        return None
    del data[property_name]
    result = write_model(key, data)
    return result


"""Persistence layer access"""
def read_model(key):
    file_name = key + '.json'
    try:
        with open(file_name, 'r') as f:
            return json.load(f)
    except IOError as e:
        print e
        return None


def write_model(key, data):
    file_name = key + '.json'
    try:
        with open(file_name, 'w') as f:
            json.dump(data, f, sort_keys=True, indent=4)
            return data
    except IOError as e:
        print e
        return None


if __name__ == '__main__':
    app.run(debug=True)

How to use

$ python api.py

The web server will start, so access and use http://127.0.0.1:5000.

Refactored and put on Github

For the time being, I wrote a test in requests and put it on Github.

https://github.com/naoiwata/simple-flask-api