phlegx/rails_query_alias_names

A question about this issue was post on stack overflow: stackoverflow.com/questions/28595636/rails-4-how-to-give-alias-names-to-includes-and-joins-in-active-record-que.

This gist has more information about the problem: gist.github.com/phlegx/add77d24ebc57f211e8b

• Model Student and model Teacher are both STI models with super class model User.

• Model Story is a STI model with super class model Task.

• Model Project has associations to all other models.

  class Project < ActiveRecord::Base
    has_many :users
    has_many :students
    has_many :teachers
    has_many :tasks
    has_many :stories
  end
  
  class Task < ActiveRecord::Base
    belongs_to :project
  end
  
  class Story < Task
  end
  
  class User < ActiveRecord::Base
    belongs_to :project
  end
  
  class Student < User
  end
  
  class Teacher < User
  end
  

• One model as parameter

  • is base model (includes(:users))

    • alias name is class name of base name (in plural)

  • is STI model (includes(:students))

    • alias name is class name of base name (in plural)

• More models as parameters

  • have more STI models with same base class name (includes(:students, :teachers))

    • first parameter (STI) -> alias name is class name of base name (in plural)

    • all other parameters (STI) -> alias name is {STI name plural}_projects

  • One base model and one STI model with same base model (includes(:users, :teachers))

    • first parameter (base) -> alias name is class name of base name (in plural)

    • second parameter (STI) -> alias name is {STI name plural}_projects

  • More STI models with different base model (includes(:students, :stories))

    • alias name is class name of base name (in plural)

The alias name depends on the parameter order in includes() or joins() and if the parameters have another parameter with same base class.

# This examples works:

Project.all.includes(:students).order('users.name ASC') # order on students

Project.all.joins(:students).order('users.name ASC') # order on students

# This examples fails

Project.all.includes(:students).order('students.name ASC')
Project.all.includes(:students).order('students_projects.name ASC')

Project.all.joins(:students).order('students.name ASC')
Project.all.joins(:students).order('students_projects.name ASC')

# This examples works:

Project.all.includes(:students, :teachers).order('users.name ASC') # order on students
Project.all.includes(:students, :teachers).order('teachers_projects.name ASC') # order on teachers
Project.all.includes(:students, :stories).order('tasks.name ASC') # order on stories

Project.all.joins(:students, :teachers).order('users.name ASC') # order on students
Project.all.joins(:students, :teachers).order('teachers_projects.name ASC') # order on teachers
Project.all.joins(:students, :stories).order('tasks.name ASC') # order on stories

# This examples fails:

Project.all.includes(:students, :teachers).order('teachers.name ASC')
Project.all.includes(:students, :teachers).order('students.name ASC')
Project.all.includes(:students, :teachers).order('students_projects.name ASC')
Project.all.includes(:students, :stories).order('stories.name ASC')

Project.all.joins(:students, :teachers).order('teachers.name ASC')
Project.all.joins(:students, :teachers).order('students.name ASC')
Project.all.joins(:students, :teachers).order('students_projects.name ASC')
Project.all.joins(:students, :stories).order('stories.name ASC')