How to fix error: werkzeug.routing.BuildError: Could not build url for endpoint 'delete' with values ['id']. Did you mean 'index' instead?

Question

I am trying to have a button in HTML that removes a row in the database when I click it. This is for a flask app. here is the HTML:

<div class="container-fluid text-center" id="products">
    {% for product in productList %}
    <div class='userProduct'>
        <a href="{{ product.productURL }}" target="_blank">{{ product.title|truncate(30) }}</a>
        <h4 class="currentPrice">${{ product.currentPrice }}</h4>
        <h5 class="budget">Budget: {{ product.userBudget }}</h5>
        <form action="{{ url_for('delete', id=product.id) }}">
            <button class="btn btn-sm btn-primary" type="submit">Remove from Wishlist</button>
        </form>
    </div>
    {% endfor %}
</div>

And here is the route in the python file

@app.route('/delete/<id>')
@login_required
def delete(id):
    remove_product = Product.query.filter_by(id=int(id)).first()
    db.session.delete(remove_product)
    db.session.commit()
    return redirect(url_for('dashboard'))

Is there anything wrong I am doing with url_for? I want to pass the id from the button to the python file so I can determine which entry to delete from the database.

Answer 1

You're probably passing ID as an integer and your route is expecting a string. Use this instead:

@app.route('/delete/<int:id>')

Answer 2

I just encountered the same error, In my case it was caused by some values being None in the database. So maybe check whether product.id has missing values.

To handle this, I needed an extra line, which would look something like this for you:

@app.route('/delete/<id>') # current line
@app.route('/delete', defaults={'id': None}) # added line which handles None

In delete(id) you then have to handle the case where id is None:

if id is None:
    ... # what should happen if id is None