Deleting rows from database with python flask?

Question

I am using a flask framework, and can't seem to delete rows from the database. The code below gives a 405 error: "The method is not allowed for the requested URL." Any ideas?

In the py:

@app.route('/delete/<postID>', methods=['POST'])
def delete_entry():
    if not session.get('logged_in'):
        abort(401)
    g.db.execute('delete from entries WHERE id = ?', [postID])
    flash('Entry was deleted')
    return redirect(url_for('show_entries', post=post))

In the html:

<a href="/delete/{{ entry.id }}"><h3>delete</h3></a>

Country

Answer 1

Clicking <a href...>delete</a> will issue a GET request, and your delete_entry method only responds to POST.

You need to either 1. replace the link with a form & submit button or 2. have the link submit a hidden form with JavaScript.

Here's how to do 1:

<form action="/delete/{{ entry.id }}" method="post">
    <input type="submit" value="Delete />
</form>

Here's how to do 2 (with jQuery):

$(document).ready(function() {
    $("a.delete").click(function() {
        var form = $('<form action="/delete/' + this.dataset.id + '" method="post"></form>');
        form.submit();
    });
});

...

<a href="#delete" class="delete" data-id="{{ entry.id }}">Delete</a>

One thing you should not do is make your delete_entry method respond to GET. GETs are meant to be idempotent (are safe to run repeatedly and don't perform destructive actions). Here's a question with some more details.

Judy

Option 1 is kinda nice. but only problem is when logging... it doesn't show it as DELETE but POST... – Sphery

Answer 2

Alternatively, change POST to DELETE to get you going.

@app.route('/delete/<postID>', methods=['DELETE'])

Ideally, you should use HTTP DELETE method.

Frustration

Here are some reasons why GET shouldn't be used for modifying data: #706282 – Judy

@user805981, true as in this question: #5163460. You would use ajax to issue 'delete' than using form method itself. – Frustration

Answer 3

I used flaskr as a base for my Flask project (as it looks like you did as well).

In the .py:

@app.route('/delete', methods=['POST'])
def delete_entry():
if not session.get('logged_in'):
    abort(401)
g.db.execute('delete from entries where id = ?', [request.form['entry_id']])
g.db.commit()
flash('Entry deleted')
return redirect(url_for('show_entries'))

In the HTML:

<form action="{{ url_for('delete_entry') }}" method=post class=delete-entry>
    <input type="hidden" name="entry_id" value="{{ entry.id }}">
    <input type="submit" value="Delete" />
</form>

I wanted a button, but you could easily use a link with the solution here.

Allergen

Answer 4

A simple <a href= link in HTML submits a GET request, but your route allows only PUT requests.

<a> does not support PUT requests. You have to submit the request with a form and/or with JavaScript code. (See Make a link use POST instead of GET.)

Mucor