How can I access a ruby object's method by using a hash syntax?

Question

I am working on Ruby on Rails, and I want to create a helper method for my view. I must pass an active record object, a symbol variable and a title to the method.

The objective of this method is to take the data, create some < strong > and < p > tags to put the title and the object attribute on the database (by accessing with the symbol variable) and get a nice HTML bit of code to put on my view.

Everything works fine, except when I need to display some of the object's attribute (like a datetime attribute, or a boolean value) which I need to call a specific object's method. For example, get the status of the user If he has confirmed his email, return string "Confirmed", if not, return string "Unconfirmed".

Helper code

module UsersHelper
    def user_show_field(user, column, title=nil)
        title ||= column.titleize
        return "<p><strong>#{title}</strong>: #{user[column]}</p>".html_safe
    end
end

View code

<%= user_show_field(@user, :city, "City") %>

In the example above, there will be no problem, because :city is a attribute from the user. So the helper method will attempt to make the call

@user[:city]

However, if I want to get the status of my user, I'll need to call the get_status method of my user:

@user[:get_status]

This Will return nil, because :get_status is not a attribute on the database of my user model: it is a method defined on my app/models/user.rb

class User < ApplicationRecord
    def get_status
        return registered ? "Email confirmed" : "Unconfirmed user"
    end

end

How can I add some code to my user model, so I can use the helper with both the attributes on the database or model's method?

arieljuod · Accepted Answer · 2019-01-31T01:32:16.113

1

You can invoke methods with a symbol or a string using send (note that you can even call private methods with send, you can use public_send instead).

@user.send(:get_status)

If your method requires parameters, just add the separated by comma:

@user.send(:another_method, param1, param2)

https://ruby-doc.org/core-2.1.0/Object.html#method-i-public_send

edited Jan 31 '19 at 01:32

answered Jan 31 '19 at 01:10

arieljuod

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Thanks, this has got the job done. How it is called this way of calling methods on ruby? To search more on google? lambda methods? – Karl Jan 31 '19 at 01:21
1

Ruby 1.9.3 is ancient and APIDock has been abandoned, you'd be better off linking to https://ruby-doc.org – mu is too short Jan 31 '19 at 01:28
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@Karl, you can read about reflection and meta programming, check this example on wikipedia https://en.wikipedia.org/wiki/Reflection_(computer_programming)#Ruby – arieljuod Jan 31 '19 at 01:34

score 1 · Answer 2 · answered Jan 31 '19 at 01:20

1

I would like to suggest instead of send all field, using one string is more simple, something like this below

module UsersHelper
  def user_show_field(user_data, title=nil)
      title ||= column.titleize
      return "<p><strong>#{title}</strong>: #{user_data}</p>".html_safe
  end
end

here you can call from your view, without change your model

   <%= user_show_field(@user.city, "City") %>
   <%= user_show_field(@user.get_status, "Status") %>

answered Jan 31 '19 at 01:20

widjajayd

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1

Sometimes simple is better than complex, thanks. However, I've always had some curiosity about how to get these kind of things done: I've always look at the models and the "before_validation :get_status" kind of thing, and I was wondering how to implement it.This was the opportunity to learn it. – Karl Jan 31 '19 at 01:25

How can I access a ruby object's method by using a hash syntax?

2 Answers2