matiaslindgren/simple-flask

Uninteresting scribbles

REST API message application

Implemented in Python using Flask, with an SQLite3 database backend.

Public facing services:

• listMessage
  • GET /messages?version=<int>&format=<str> returns a list of all messages in the application
    • Version 1 returns a JSON list of all messages in short form, i.e. only keys title, sender, and url.
    • Version 2 returns a JSON or XML list of all messages in long form.
• createMessage - public facing service
  • PUT /messages creates a new message from title, content, sender, and url values specified in the JSON body of the request and returns an id for the created message.

Private service:

• database
  • GET /messages returns a JSON list of all messages in the SQL database.
  • PUT /messages creates a new message from given JSON data and returns the row id of the created message

Setup

Tested with Python 3.7.3 on Debian 10 (buster).

pip install -r requirements.txt

Running

The shell is assumed to be bash. In addition, the jq JSON formatting utility is used for pretty-formatting JSON.

1. Change working directory to this repository.

2. Create a directory for the SQLite database:

    export DATABASE_DIR="$(mktemp --directory)"
   

3. Initialize the database:

    env FLASK_APP=database/main.py flask db init
   

4. Start the database service:

    env FLASK_APP=database/main.py flask run --port 5000
   

5. In a second terminal, start the listMessage service:

    env FLASK_APP=listMessage/main.py DATABASE_URL='http://127.0.0.1:5000' flask run --port 5001
   

6. In a third terminal, start the createMessage service:

    env FLASK_APP=createMessage/main.py DATABASE_URL='http://127.0.0.1:5000' flask run --port 5002
   

The application is now initialized and ready to serve requests.

Examples

In a fourth terminal, check that listMessage returns empty lists:

    >>> curl --request GET 'http://127.0.0.1:5001/messages?version=1'
    []

    >>> curl --request GET 'http://127.0.0.1:5001/messages?version=2&format=xml'
    <?xml version="1.0" encoding="UTF-8" ?><root></root>

Now, insert some messages using the createMessage service:

    >>> curl --header 'Content-Type: application/json' \
        --request PUT 'http://127.0.0.1:5002/messages' \
        --data '{"title": "hello", "content": "hi, how goes it?", "sender": "bob", "url": "https://yle.fi"}'
    {"created_id": 1}

    >>> curl --header 'Content-Type: application/json' \
        --request PUT 'http://127.0.0.1:5002/messages' \
        --data '{"title": "re: hello", "content": "hi, all good here.", "sender": "alice", "url": "https://yle.fi"}'
    {"created_id": 2}

    >>> curl --header 'Content-Type: application/json' \
        --request PUT 'http://127.0.0.1:5002/messages' \
        --data '{"title": "special offer", "content": "limited time only, -50% for you", "sender": "mr. spam-king", "url": "https://example.com/spam"}'
    {"created_id": 3}

The listMessage service should now return non-empty lists:

    >>> curl --request GET 'http://127.0.0.1:5001/messages?version=1' | jq .
    [
      {
        "title": "hello",
        "content": "hi, how goes it?",
        "sender": "bob"
      },
      {
        "title": "re: hello",
        "content": "hi, all good here.",
        "sender": "alice"
      },
      {
        "title": "special offer",
        "content": "limited time only, -50% for you",
        "sender": "mr. spam-king"
      }
    ]

    >>> curl --request GET 'http://127.0.0.1:5001/messages?version=2&format=xml' | python3 -c 'import sys; from xml.dom.minidom import parseString; print(parseString(sys.stdin.read()).toprettyxml())'
    <?xml version="1.0" ?>
    <root>
        <item type="dict">
            <id type="int">1</id>
            <title type="str">hello</title>
            <content type="str">hi, how goes it?</content>
            <sender type="str">bob</sender>
            <url type="str">https://yle.fi</url>
        </item>
        <item type="dict">
            <id type="int">2</id>
            <title type="str">re: hello</title>
            <content type="str">hi, all good here.</content>
            <sender type="str">alice</sender>
            <url type="str">https://yle.fi</url>
        </item>
        <item type="dict">
            <id type="int">3</id>
            <title type="str">special offer</title>
            <content type="str">limited time only, -50% for you</content>
            <sender type="str">mr. spam-king</sender>
            <url type="str">https://example.com/spam</url>
        </item>
    </root>