Select without id field (Ror)

Question

I am with a very silly doubt, I am making a system with Ruby on Rails and I need to make a select where the id field does not come, the problem is that this field is always present, for example: Employee.select('nome, email').all

The above code should return several records and bring only the name and email fields as I am configuring, as with other fields, but the id is nil, but does not disappear, the record looks like this:

{
  id: null,
  name: "CRISTINA EXEMPLO",
  email: "Executiva de Atendimento"
}

How do I remove this field objectively, because I know I could iterate on the result and create a simple list, but I believe that Rails supports solving this without great maneuvers.

I hope I’ve been clear and I look forward to a little help, vlw.

Answer 1

Alessandro, this issue of yours is complicated and requires us to understand some things:

1) If you want to return an object without the attribute id, Rails won’t do it, and I’ll explain why:

You created a class, the model ActiveRecord which is implicitly linked to the bank records. As in Rails everything is by convention, it admits that its class declares the attributes referring to the fields in the table to which it is bound. And we know that every object generated by a class must respect its methods and attributes in which the class has defined. Therefore, if you create (implicitly) a class that has the attribute id, how could you have an object generated by this class without this attribute?

If you really want an object that contains only the attributes that suit you, you should encapsulate this result in another object defined by a new class (it could be a Struct or OpenStruct same). She would play the role of a DTO (Data Transfer Object).

2) If you want to return a standard hash, only with these fields:

Well, then you should make a loop and assemble your Hash, there is no way, because the Rails as quoted above, will always respect the contract defined by the class (implicitly). So even if you ask it to return as an object Hash, it will be based on the attributes of your model.

My suggestion

You want to return an object of the type Hash or another object you want to define (option 1), why you don’t create a method in your model that does this for you. The iteration to create a Hash or mount a new object (could be a Struct) is very simple, and you wouldn’t expose this to the rest of the application. Something like:

class Employee < ActiveRecord::Base
  def self.all_with_fields_that_i_want
    all.map do |e|
      OpenStruct.new({name: e.name, email: e.email})
    end
  end
end

results = Employee.all_with_fields_that_i_want

Answer 2

You can use method except

http://apidock.com/rails/ActiveRecord/SpawnMethods/except

Example

Model.find(10).order('id asc').except(:id)

Or else at the time of mounting a . each you can reject a :field

Example

<% @model.reject(&:password_digest?).each do |attribute| %>

Answer 3

Model.select('field AS field_one').first.field_one   
# => "value"

I checked the method documentation select see if this solves.

Answer 4

You can also use active record and make a map

Model.where(name: 'Cristina', email: '[email protected]').map{|m| {name: m.name, email: m.email}}