[Fixed]-'str' object is not callable – SuccessMessageMixin

I got exactly this same message when I accidentally used the messages framework incorrectly in the form_valid method of a completely different view in my project.

The correct code should have been:

messages.success(request, "Deactivated product")


But what I had written instead was

messages.success = "Deactivated product"


This code doesn’t work, but it doesn’t cause an error on the page, either! However, as soon as I submitted a different form that used the SuccessMessageMixin, I would see the 'str' object is not callable error.

(Having a problem on one page cause an error on a completely different page was fun to debug.)