How to delete a record using Flask & SQL Server as backend?

Question

I'm creating basic Flask website & API.

I want to delete a record from SQL Server. I managed to work out creating & updating records.

I've came up with the following:

api2.py

import secrets
import pdb
secret = secrets.token_urlsafe(32)
from flask import Flask,render_template,url_for, request, redirect, flash
import pyodbc

app = Flask(__name__)
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['SQLALCHEMY_ENGINE_OPTIONS'] =None
app.config['SESSION_TYPE'] =  'memcached' 
app.secret_key = secret

conn = pyodbc.connect('Driver={SQL Server};'
                        'Server=127.0.0.1;'
                        'Database=AdventureWorksDW2019;'
                        'UID=sa;'
                        'PWD=xxx;'
                        'Trusted_Connection=no;')

@app.route('/', methods= ['GET'])
def home():
    cursor = conn.cursor()
    cursor.execute("SELECT * FROM notes")
    productDetails= cursor.fetchall()
    return render_template('home.html', 
                    productDetails=productDetails)

@app.route('/delete/<string:id>', methods= ['DELETE'])
def delete(id):
    if request.method=='DELETE':
        cursor=conn.cursor()
        productDetails1=cursor.execute("DELETE FROM notes WHERE id=?", (id))
        conn.commit()
        cursor.close()
        return redirect('/')

home.html

{% extends 'base.html' %}
{% set active_page = 'home' %}
{% block content %}

<table bolder= 1px>
  <tr>
          <td> id </td>
          <td> note </td>
          <td> admin </td>

  </tr>
{% for note in productDetails %}
<tr>
  <td> {{note[0]}} </td>
  <td> {{note[1]}} </td>

  <td> <a href='/edit/{{note[0]}}'>Edit</a> <a href='/new_item'>Add</a> <a href='/delete/{{note[0]}}'>Delete</a>  </td>

</tr>
{% endfor %}
</table>
{% endblock %} -->

I'm stuck with an error below when I click a link on the generated url in the table:

url: http://127.0.0.1:5000/delete/3

Method Not Allowed The method is not allowed for the requested URL.

score 1 · Answer 1 · answered Oct 11 '21 at 11:56

When you are writing <a href='/delete/{{note[0]}}'>Delete</a>, the client browser will generate a GET request to your server (when the link is clicked). And your endpoint @app.route('/delete/<string:id>', methods= ['DELETE']) only allows DELETE requests.

Creating a DELETE request is not very well supported by HTML clients : Are the PUT, DELETE, HEAD, etc methods available in most web browsers?

Two workarounds possibles:

replace the hyperlink with a form with a POST request, and adapt delete(id) function : https://stackoverflow.com/a/24794230/11405279
adapt to use ajax request : Python flask DELETE request

How to delete a record using Flask & SQL Server as backend?

1 Answers1