29 February 2020 Updated 29 February 2020
by
Peter
I never really checked if CSRF protection was working in my Flask application, this website. Is it enabled by default? From the Flask_WTF extension documentation:
Any view using FlaskForm to process the request is already getting CSRF protection.
And from the text of Miguel Grinberg's post 'Cookie Security for Flask Applications':
If you are handling your web forms with the Flask-WTF extension, ...
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22 February 2020 Updated 22 February 2020
by
Peter
While working on comments system for the first time I bounced into the problem of having multiple WTForms forms on a single page. On every page there also is the search form but this is not a POST form. It is doing a GET. The comments system uses two forms:
Comment form
Comment reply form
The comment form is immediately below the content item, blog post or page, the comment reply form is initially ...
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15 February 2020 Updated 18 February 2020
by
Peter
I hoped to tell you today that you could comment on the blog posts of this website now. That would have meant that I completed the first implementation of the comments system. Unfortunately I stumbled upon some problems, yes of course, I am a programmer, and one of them involved the TextAreaField.
I just wanted a simple extended version of the WTForm TextAreaField, just add a character counter field ...
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8 February 2020 Updated 16 February 2020
by
Peter
Now that I have blog posts, pages and a contact form, I decided to implement the comments for the blog posts and pages. Not just flat comments but threaded comments, also called nested comments. Some months ago I read about this and I really liked Miguel Grinberg's article: Implementing User Comments with SQLAlchemy.
As often Miguel starts with defining the problem and some hard core theory and explaining ...
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30 January 2020 Updated 30 January 2020
by
Peter
When you start with Flask you read a bit about the Application Context, TL;DR. Do not know about you but I certainly did not understand it fully. What is app, what is current_app, what is the difference, you just start programming your application. All the time in the background there is this weird buzz: what exactly is the Application Context ... Then at a certain moment when using a class you instantiated ...
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24 January 2020 Updated 24 January 2020
by
Peter
When you sign up for this website you are assigned an avatar image. Of course you can change the avatar in 'your account' and this is done using an image picker. Many image pickers examples can be found on the internet. But this is a Flask site including WTForms and I want the image picker to be generated by the wonderful Jinja macro I am using, see also link below, ok, I modified it a bit. With this ...
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13 January 2020 Updated 13 January 2020
by
Peter
Time for joy or crisis: running the OWASP Zed Attack Proxy (ZAP) application to check vulnerabilities of our web application. Developers often know there are weak points in their code, but there always is a date of delivery. So why not use a tool that list the well-known and important ones? This is my first time using ZAP so if are an expert you best stop reading here. In the links below there ...
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6 January 2020 Updated 9 January 2020
by
Peter
This Flask website is multilanguage. The implementation is described in previous posts. So far all my translations were in the Python code and the HTML templates. On a few places I needed some translations in Javascript and did this by pulling this Javascript code inline in the HTML template. For example, for forms I needed:
e.target.setCustomValidity('Please fill out this field.');
I ...
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27 December 2019 Updated 27 December 2019
by
Peter
You created a Flask web application, it is running fine and using https. But is it secure enough? Did you do everything to protect your visitors, did you do everything to prevent malicious attacks?
A good way to proceed on this is to pentest your site. Penetration testing tools, or pen testing tools, can identifying security weaknesses. They identify vulnerabilities in the web application that can ...
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9 December 2019
by
Peter
Again another unexpected Docker issue. In a previous post I described why and how you must force Docker to use a subnet, to prevent sudden unexpected changes in the network with consequences like mail no longer working.
This post is about Docker not respecting firewall settings, at least when running Debian / Ubuntu and ufw (Uncomplicated Firewall). Docker does not tell you this, and exposes ports, ...
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Welcome
This website is a multi-language CMS / Blog I build with Python, the framework Flask and SQLAlchemy. It is deployed on my ISPConfig3 (Nginx + Mariadb) server using Docker which is also used for development. Read more
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- Two Flask apps, frontend and admin, on one domain using DispatcherMiddleware
- SLQAlchemy dynamic query building and filtering including soft deletes
- Flask with multiple forms on a page posted using AJAX and returning a rendered form result
- Adding url_for() links to Jinja templates of a Flask multilanguage website
- SQLAlchemy server-side datetime calculations
- OWASP Zed Attack Proxy (ZAP) security testing