Modified Preorder Tree Traversal

20 May 2016 This was a great explanation of Modified Preorder Tree Traversal (or MPTT): https://www.sitepoint.com/hierarchical-data-database-2/

A common use-case for MPTT is categorization data, like with the way django-oscar uses django-mptt: https://github.com/django-mptt/django-mptt

Datatables - Uncaught TypeError: Cannot read property 'style' of undefined

09 May 2016 If you see this error in datatables: "Uncaught TypeError: Cannot read property 'style' of undefined"

It's likely that you're missing a header column in your table. Make sure you have the same number of <th> elements as items in the "columns" section of your datatables initialization.

Select2 Replacement

08 May 2016 This selectize.js library looks like a good replacement for Select2: https://selectize.github.io/selectize.js/

Javascript Data Tables

05 May 2016

https://fooplugins.github.io/FooTable/index.html - good, no inline editing though
https://datatables.net/ - editable plugin requires purchase
https://github.com/mleibman/SlickGrid - unmaintained
https://handsontable.com/ - responsiveness doesn't work very well
https://github.com/mindmup/editable-table - only supports editing
https://github.com/David-Mulder/paper-datatable - pretty, but doesn't seem very battle-tested
https://www.ag-grid.com/ - no tests
https://github.com/angular-ui/ui-grid - requires angular
http://ng-table.com/ - requires angular
http://backgridjs.com/ - requires backbone
https://github.com/daniel-nagy/md-data-table - pretty, but requires angular
https://www.dynatable.com/ - not editable
http://www.jtable.org/ - last updated in 2014, styling looks dated
https://datazenit.com/static/sensei-grid/examples/ - simple, editable

Falsehoods programmers believe about time and time zones

19 Apr 2016 This article has a lot of great lessons learned about timezones: http://www.creativedeletion.com/2015/01/28/falsehoods-programmers-date-time-zones.html

SQLAlchemy - JSON not changing on commit

10 Apr 2016 If your changes to a JSON, JSONB, or HSTORE field aren't saving after you commit, then you need to wrap your field in the MutableDict shown here: http://docs.sqlalchemy.org/en/latest/dialects/postgresql.html#sqlalchemy.dialects.postgresql.HSTORE

SQLAlchemy - AttributeError: type object 'JSONB' has no attribute 'lower'

10 Apr 2016 This error happened because I mistyped "db.column" instead of "db.Column" when I was creating my database model using SQLAlchemy.

This might be your problem if db.create_all() isn't creating all the columns you expected.

PHP - Problems With Long Running Processes

19 Mar 2016 Great article about the problems with using PHP for long running processes: https://software-gunslinger.tumblr.com/post/48215406921/php-is-meant-to-die-continued

Describes the main reason why I started using Python for long-running jobs.

Ansible Vault - storing secrets in repos

04 Mar 2016 When others are deploying a project for you, it's easy for mistakes to be made when secrets must be updated in environmental variables. Ansible-vault takes a different approach and encrypts the secrets - allowing you to store the secrets in your repo.

To encrypt a file: ansible-vault encrypt secrets.py
To decrypt a file: ansible-vault decrypt secrets.py

More documentation is available here: http://docs.ansible.com/ansible/playbooks_vault.html

Python - isort, useful tool for sorting python imports

04 Mar 2016 http://timothycrosley.github.io/isort/

I saw it in the django coding style documentation: https://docs.djangoproject.com/en/1.9/internals/contributing/writing-code/coding-style/

To make an entire project's imports easier to read, all you need to do is:

pip install isort
isort -rc .

There's also a sublime plugin for it here: https://github.com/thijsdezoete/sublime-text-isort-plugin#install

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