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Flask (Reference) · Lesson 45 of 56

Flask API

Source: 13-Flask/flask/api.py

Start here — no coding background needed

What you will learn

Return JSON for mobile apps and frontends.

In simple words

API = machine-readable answers instead of pretty HTML pages.

Build websites with Python — read for overview; run full apps on your computer later.

Easy example — try this first

Easy example — run this first. Change values and press Run again.

Python

Runs in your browser via Pyodide — no server. First run may take a few seconds.

Reference notes (from full bootcamp)

Optional — deeper detail for when you are ready

Reference script from the bootcamp repo. Read the code below; run a simplified version in the playground when marked runnable.

Example HCL
HCL
### Put and Delete-HTTP Verbs
### Working With API's--Json

from flask import Flask, jsonify, request

app = Flask(__name__)

##Initial Data in my to do list
items = [
    {"id": 1, "name": "Item 1", "description": "This is item 1"},
    {"id": 2, "name": "Item 2", "description": "This is item 2"}
]

@app.route('/')
def home():
    return "Welcome To The Sample To DO List App"

## Get: Retrieve all the items

@app.route('/items',methods=['GET'])
def get_items():
    return jsonify(items)

## get: Retireve a specific item by Id
@app.route('/items/<int:item_id>',methods=['GET'])
def get_item(item_id):
    item=next((item for item in items if item["id"]==item_id),None)
    if item is None:
        return jsonify({"error":"item not found"})
    return jsonify(item)

## Post :create a new task- API
@app.route('/items',methods=['POST'])
def create_item():
    if not request.json or not 'name' in request.json:
        return jsonify({"error":"item not found"})
    new_item={
        "id": items[-1]["id"] + 1 if items else 1,
        "name":request.json['name'],
        "description":request.json["description"]


    }
    items.append(new_item)
    return jsonify(new_item)

# Put: Update an existing item
@app.route('/items/<int:item_id>',methods=['PUT'])
def update_item(item_id):
    item = next((item for item in items if item["id"] == item_id), None)
    if item is None:
        return jsonify({"error": "Item not found"})
    item['name'] = request.json.get('name', item['name'])
    item['description'] = request.json.get('description', item['description'])
    return jsonify(item)

# DELETE: Delete an item
@app.route('/items/<int:item_id>', methods=['DELETE'])
def delete_item(item_id):
    global items
    items = [item for item in items if item["id"] != item_id]
    return jsonify({"result": "Item deleted"})




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

Browser practice only — full example needs Python on your computer (files, Flask, threads, etc.).

Practice test — try yourself

Write code, press Check. Wrong answer shows the correct code to copy & run.

You learned "Flask API". Use print() to show: Done: Flask API

Hint: Use one print() with the exact text.

Python