Definitely useful! Debug code for development in Ruby on Rails

What is this, what is this

Hello.

I think that the most required technology for development is debugging ability. Especially for me who is good at mass-producing bugs, debugging ability is very important.

Therefore, I would like to put together the debugging code that I usually use in development.

Debug code

I will write a list of code that can be used in Ruby on Rails and may be useful for debugging. There is also code that can be used in Ruby.

It is supposed to be used when starting byebug or with rails console. If you are not sure how to use byebug, please use it in the following article. https://web-nari.net/2018/03/16/byebug/

Method list

Returns a list of methods that can be referenced by the variable hoge and whose method name contains method_name.

hoge.methods.select {|name| name.to_s.include?("method_name") }

Method definition location

Returns the class in which the foo method that can be referenced by the variable hoge is defined.

hoge.method(:foo)

Source file path

Returns the path of the file in which the foo method that can be referenced by the variable hoge is defined.

hoge.method(:foo).source_location

Callback search

Returns a list of save callbacks defined in the class Hoge. If after or before is given to the argument of cb.kind.eql?, the callbacks defined in the after_callback function and the before_callback function are returned, respectively.

Hoge._save_callbacks.select { |cb| cb.kind.eql?(:after) }.map { |cb| cb.filter }

Other callback functions

In addition to save, the following callback functions can be used respectively.

=> [:validate,
 :validation,
 :initialize,
 :find,
 :touch,
 :save,
 :create,
 :update,
 :destroy,
 :commit,
 :rollback,
 :before_commit,
 :before_commit_without_transaction_enrollment,
 :commit_without_transaction_enrollment,
 :rollback_without_transaction_enrollment]

For example, if you want to know the list of after_validation callbacks, do as follows.

Hoge._validation_callbacks.select { |cb| cb.kind.eql?(:after) }.map { |cb| cb.filter }

Classification

Converts the name : string to the appropriate class. In the case of the example, String is returned. A NameError: uninitialized constant is raised if there is no such class.

:string.to_s.classify.constantize

Class confirmation

Check the class of the object named hoge.

hoge.class

Search for inheritance source

You can also search for inherited classes of the object hoge and their ancestors.

hoge.superclass #Find parent class
hoge.ancestors #Search for ancestors

Check instance variables

Returns the instance variable that the object named hoge has. Class variables can be referenced with class_variables.

hoge.instance_variables

Summary

When I wrote it for the momentum of the title, it was very few.

We will continue to add more.