25 August 2019 Updated 30 August 2019 by Peter
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When I started this project, this website, I kept in mind that it had to support multiple languages. But of course I did not really look into database design because of all the other things I had to learn, add and implement. After a certain moment I could display and select multiple languages but that was for the texts in the code and templates and not for the database content items like blog posts ...
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14 August 2019 Updated 14 August 2019 by Peter
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This post is about editing code, a lot of editing, huge amounts of editing! When you implement much functionality, you notice things that need attention, things that need you to research, how do others do this, what is the plural of certain words, etc. I maintain a todo list and every time I noticed something that needed attention I added it to this list. The list got too big so I decided to stop adding ...
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7 August 2019 Updated 30 August 2019 by Peter
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With a single language there is not really a problem, we just forget about the rest of the world and build our single language Flask application. We start getting a headache when the website must support multiple languages. What exactly is a website supporting multiple languages? How many languages will be supported, and which languages? For English there are for example en-GB and en-US. Which parts ...
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29 July 2019 Updated 29 August 2019 by Peter
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Performance is a never ending story. At a certain moment I noticed that putting the home page on the screen took some 370 milliseconds using the Flask development server with debug messages shown. That seemed far too long! How did I notice this? Because at the bottom of every page I show the time it takes to generate a page. Please note that the timings below are from a more optimized version of the ...
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26 July 2019 Updated 13 August 2019 by Peter
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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 ...
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4 July 2019 Updated 29 August 2019 by Peter
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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 ...
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28 June 2019 Updated 31 August 2019 by Peter
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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 ...
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24 June 2019 Updated 31 August 2019 by Peter
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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 ...
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21 June 2019 Updated 29 August 2019 by Peter
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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 ...
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17 June 2019 Updated 31 August 2019 by Peter
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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 ...
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