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Rails 4 - how to give alias names to includes() and joins() in active record quering
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| See question on stack overflow: http://stackoverflow.com/questions/28595636/rails-4-how-to-give-alias-names-to-includes-and-joins-in-active-record-que | |
| - Model Student and model Teacher are both STI models with super class model User | |
| - Model Place is a STI model with super class model Location | |
| - includes() and joins(), both fails | |
| Rails alias naming convention (includes() and joins()) | |
| - 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, :places)) | |
| -> 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. |
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| # all models | |
| class Project < ActiveRecord::Base | |
| has_many :students | |
| has_many :teachers | |
| has_many :places | |
| end | |
| class Location < ActiveRecord::Base | |
| belongs_to :project | |
| end | |
| class Place < Location | |
| end | |
| class User < ActiveRecord::Base | |
| belongs_to :project | |
| end | |
| class Student < User | |
| end | |
| class Teacher < User | |
| end | |
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| # CASE ONE (single STI model include) | |
| # 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') | |
| # CASE TWO (double STI model include with same base model) | |
| # 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, :places).order('locations.name ASC') # order on places | |
| 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, :places).order('locations.name ASC') # order on places | |
| # 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, :places).order('places.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, :places).order('places.name ASC') |
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Thanks 👍 Really useful.
Is it possible to force JOIN alias? It would be really useful for dynamically created queries
Then these two would work: