How to reload a belongs_to association
To reload a single-item association in Rails 5+, call #reload_<association>:
post.reload_author
In older Railses you can say
post.author(true)
Related cards:
Rails: How to use a n:m association as 1:n association
Sometimes you might want to limit the number of associated records in a has_many association, but cannot add a foreign key to the other model (using belongs_to).
There are [many](http://stackoverflow.com/questions/8153051/rails-how-to-limit-n...
How to tell ActiveRecord how to preload associations (either JOINs or separate queries)
Remember why preloading associations "randomly" uses joined tables or multiple queries?
If you don't like the cleverness of thi...
How to make changes to a Ruby gem (as a Rails developer)
At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (> 1M downloads), active_type (> 1M downloads), and geordi (> 200k downloads)
Developing a Ruby gem is different from developing Rails applications, w...
How to mirror a git repo to a new remote
Say you want to move a git repository from one remote (perhaps Github) to another (perhaps Gitlab).
If you have the repo checked out, you still should make sure to mirror all branches of the old remote, not only those you happen to have checked o...
How to move all files in a folder to a new subfolder
Let's say you have a folder images and want to to move all files in there to a new subfolder public.
cd images
mkdir public
mv !(public) public
The !(public) excludes the new subfolder itself from being moved.
Bash: How to grep logs for a pattern and expand it to the full request
Example
I, [2024-01-21T06:22:17.484221 #2698200] INFO -- : [4cdad7a4-8617-4bc9-84e9-c40364eea2e4] test
I, [2024-01-21T06:22:17.484221 #2698200] INFO -- : [4cdad7a4-8617-4bc9-84e9-c40364eea2e4] more
I, [2024-01-21T06:22:17.484221 #269820...
How to install a specific version of RubyGems (and how to downgrade)
Sometimes you want one distinct version of RubyGems to be installed to replicate the same behavior across multiple servers.
Usually would do this to update your RubyGems, but this always takes you to the latest version:
gem update --system
...
How to check if a file is a human readable text file
Ruby's File class has a handy method binary? which checks whether a file is a binary file. This method might be telling the truth most of the time. But sometimes it doesn't, and that's what causes pain. The method is defined as follows:
How to load only a subset of a massive MySQL dump
I had a huge MySQL dump that took forever (as in: days) to import, while I actually just wanted to have the full database structure with some data to use on my development machine.
After trying several suggestions on how to speed up slow MySQL du...