How to use database triggers in Rails

1. Ruby on Rails

   1 541 56,987 10.0 Ruby

   Ruby on Rails

   

   I don't think it is superfluous to clarify to folks who might not be familiar with Rails how migrations work. In Rails, we create classes for migrations in the db/migrate folder that inherit from ActiveRecord::Migration[:rails_version]. This is a good example of metaprogramming in Ruby. Instead of directly inheriting from the ActiveRecord::Migration class, ActiveRecord::Migration has redefined the [] (square brackets) method to dynamically create a class with features available for the specified Rails version and return it, so we can inherit from it. This allows us to use migrations created in previous versions of Rails even after updating Rails. The newly created class typically has two methods, up and down, which apply and revert the changes to the database, respectively. Alternatively, it might have a single change method if the changes can be automatically reversed by Rails. The name of the file containing the class starts with a 14-digit timestamp, and Rails maintains a table with one column containing these timestamps for executed migrations. This ensures that migrations are run only once and in the order they were created when you type rails db:migrate. This system ensures smooth database schema changes and consistency across different environments. It's important to mention that the SQL code we will write in the next section will be compiled and executed by the database engine, so if we need to make changes, we need to revert the migration, change the code, and execute it again. You can read more about migrations here: Rails Migrations Guide.

2. InfluxDB

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3. portfolio

   2 1 0 4.6 Ruby

   My portfolio app (by Gavrilajava)

   

   Now, everything should be working smoothly. You can find a working example here, and the source code is available in this GitHub Repository. If you have any suggestions or feedback, please feel free to leave a comment.

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