Advanced ActiveRecord Querying - Custom Joins

This topic is for the Custom Joins exercise in the Advanced ActiveRecord Querying trail. Post any questions, comments, or pointers you have to share with other Upcase subscribers.

What is here? Ids of people or locations? Or is it ids of rows in the temporary table generated just for querying? Very curious about understanding this!

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Hi @kiramclean, I think the Naive joins method section of the Custom Joins video will do the best job of explaining this, but I think the short answer is that the will be a Person, referenced from the join table combining the person and the location.

What does the <> mean in the code:

joins(location: :people).where(" <>").distinct

<> is the operator for “not equal to” in SQL. Many database systems also accept !=, but <> is the ANSI official operator. SQL operators refernece

I found an issue with this exercise. I think a .ruby-version file needs to be added to the exercise repo.

I am using chruby, and have my default version set to ruby-2.3.3. I was able to run bin/setup. But every time I tried to run rake, I got an error:

$ rake
rake aborted!
NoMethodError: undefined method `last_comment' for #<Rake::Application:0x0055792d432438>
/home/hunter/.gem/ruby/2.3.3/gems/rspec-core-3.3.2/lib/rspec/core/rake_task.rb:82:in `define'
/home/hunter/.gem/ruby/2.3.3/gems/rspec-core-3.3.2/lib/rspec/core/rake_task.rb:62:in `initialize'
/home/hunter/practice/upcase/custom-joins/Rakefile:5:in `new'
/home/hunter/practice/upcase/custom-joins/Rakefile:5:in `<top (required)>'
/home/hunter/.gem/ruby/2.3.3/gems/rake-12.0.0/exe/rake:27:in `<top (required)>'

I decided to switch to ruby-2.3.0, since that was the version used in the last exercise in this trail. It fixed the problem, and I was able to run my specs.