- Don't Repeat Yourself (DRY) with Jinja2
- SQLAlchemy, PostgreSQL, maximum number of rows per user
- Show the values in SQLAlchemy dynamic filters
- Secure data transfer with Public Key encryption and pyNaCl
- rqlite: a high-availability and distributed SQLite alternative
- Should I migrate my Docker Swarm to Kubernetes?
- Using Python's pyOpenSSL to verify SSL certificates downloaded from a host
- Using UUIDs instead of Integer Autoincrement Primary Keys with SQLAlchemy and MariaDb
- Connect to a service on a Docker host from a Docker container
- SQLAlchemy: Using Cascade Deletes to delete related objects
- Using PyInstaller and Cython to create a Python executable
- Flask RESTful API request parameter validation with Marshmallow schemas
26 July 2019 0
In Flask we have the config object which can be used to specify database parameters, email parameters, etc. When we run a Flask program it first creates the application. Once the application has been created subsequent requests skip the app creation and are redirected to the blueprint views. When Flask starts, the config variables are loaded and used. Important to understand is that every visitor ...
4 July 2019 0
In the past I wrote a captcha in PHP to limit email newsletter sign ups, worked fine, in fact it is still in use today. You cannot really block spam registrations. There are registration robots but there are also people being paid a few bucks to flood your website with fake or troll accounts. That is the reality and we have to face it. And now there is also deeplearning that can be used to break our ...
28 June 2019 0
In the endless number of problems you encounter, and solve, when starting to use new technology I was facing a new one: how to send email from my Python Docker app using the ISPConfig host MTA (Mail transfer Agent). I found there are two ways to do this: Send mail from our container to port 25 of the host where the MTA is listening on Write the mail file to a directory on the host and use a script ...
24 June 2019 5
You will find a lot of SQLAlchemy datetime calculation examples using e.g. Python's timedelta function. Why? I do not understand this except that this is easy. But is it correct? Assume we we want all user records or objects created two hours ago and the record / object definition is: class User(Base): __tablename__ = 'user' id = Column(Integer, primary_key=True) created_on ...
21 June 2019 1
Building on the previous post 'Flask, Jinja2 and SLQAlchemy many-to-many relationship with conditions' I looked for a way to dynamically add filter conditions and if possible also find a solution for the soft delete pattern. Soft delete is not deleting records from a table but instead marking them as deleted. This means that every table must have a deleted flag and all queries must exclude records ...
17 June 2019 0
Disclaimer: This my first SQLAlchemy project so I am not experienced and may make wrong statements in this post. While working on my first Flask / SQLAchemy project (I do not use Flask-SQLAlchemy) I hit a very high and thick wall. To explain this, consider you have a blog with posts and tags. There is a many-to-many relationship between posts and tags: a post can have many tags and a tag can have ...
1 June 2019 0
For this blog I wanted the blog post page to have three 'columns'. Why did I quote the word columns? Because what is a column on a large screen can be a row on a mobile device. Bootstrap uses containers, rows and columns. And of course, a Bootstrap column can show on the screen as a column or a row. Help! When designing a layout we must not think about columns but about screen elements and how we ...
10 March 2019 1
When using docker we want the size of the docker image to be minimal. Why? Many reasons. Memory footprint is one especially when running many Python Flask websites on an ISPConfig3 server. Fortunately, from docker 17.05 we can use multistage builds. Using this we reduce our image size from 376MB to 211MB! Below are two images we can use: > docker images python 3.6-alpine 1837080c5e87 5 ...
9 March 2019 1
By default Alembic does not change the length of string fields, I noticed this after changing a string field from: description = Column(String(150), server_default='') to: description = Column(String(250), server_default='') No changes were made. It appears that column type change detection is off by default, so you can test it first, and can be turned on by adding 'compare_type=True' to the context. ...
13 February 2019 0
This is a post showing how to run a Flask app on ISPConfig3. Why? I have a VPS on the internet running Debian and ISPConfig3. It is running static sites and PHP sites. But now I also want to run my Flask python apps here. This way I can use the domain management I am used to and do not need an extra server for Python apps. This solution uses Docker to run the Flask app, printing 'Hello world', and ...