flaskapi.py

from flask import Flask, request, jsonify
import pandas as pd

app = Flask(__name__)

@app.route('/api/users', methods=['POST', 'GET', 'DELETE'])
def users():
    # gets all users
    if request.method=='GET':
    
        df = pd.read_csv('users.csv')
        return {'users': df.to_dict()}, 200
    
    # inserts new user
    if request.method=='POST':

        #insert new row in dataframe
        df = pd.read_csv('users.csv')
        data = request.get_json()
        user=[data['userid'], data['name'], data['bookid']]
        df = df.append(pd.Series(user, index=df.columns), ignore_index=True)
        df.to_csv('users.csv', index=False)
        
        return {'message': 'user added'}, 201
    
    # deletes a user
    if request.method=='DELETE':
        
        df = pd.read_csv('users.csv')
        data = request.get_json()
        df = df[df.name != data['name']]
        
        df.to_csv('users.csv', index=False)

        return {'message': 'user deleted'}, 200

@app.route('/api/books', methods=['GET'])
def books():
    # gets all books
    df = pd.read_csv('users.csv')
    data = request.get_json()
    user = data['user']
    
    if df[df.name == user].empty:
        return {'message': 'user not found'}, 404
    
    bookid = df[df.name == user].bookid.values[0]
    booksdf = pd.read_csv('books.csv')
    book = booksdf[booksdf.bookid == bookid]

    return {'book': book.to_dict()}, 200

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