Step 2: Declaring Methods

Now that you have a running application, you can begin declaring JSON-RPC methods. A method is simply a Python function decorated with @jsonrpc.method("<name>").

In this step, you will:

  • define your first method

  • call it using a JSON-RPC request

  • see how method names form a global namespace

Your First Method

Open app.py and add:

@jsonrpc.method("ping")
def ping():
    return "pong"

Restart the server:

python app.py

Call it using curl:

curl -X POST http://127.0.0.1:5000/api \
     -H "Content-Type: application/json" \
     -d '{"jsonrpc":"2.0","method":"ping","id":1}'

You should see:

{"jsonrpc": "2.0", "result": "pong", "id": 1}

Method Names and Grouping

Method names in JSON-RPC form a flat namespace. However, Flask-JSONRPC allows you to emulate structured namespaces:

@jsonrpc.method("math.add")
def add(a, b):
    return a + b

@jsonrpc.method("math.mul")
def mul(a, b):
    return a * b

These names appear grouped under math in the explorer.

Browse the Explorer

Visit:

http://127.0.0.1:5000/api/browse

You will now see:

  • ping

  • math.add

  • math.mul

Click any method to view its description. Later, you will learn to control the metadata shown in the explorer using docstrings and type hints.