Rails naming convention for join table
Ruby on-RailsRuby on-Rails-3Ruby on-Rails-3.1Rails MigrationsRuby on-Rails Problem Overview
This questions stems from: https://stackoverflow.com/questions/11313872/how-to-link-form-after-creating-rails-join-table
I am creating the join table between my Product and Category Models.
What should the join table be named? categories_products or category_products or something else?
Ruby on-Rails Solutions
Solution 1 - Ruby on-Rails
categories_products
. Both plural. In lexical order.
> Unless the name of the join table is explicitly specified by using the > :join_table option, Active Record creates the name by using the > lexical order of the class names. So a join between customer and order > models will give the default join table name of “customers_orders” > because “c” outranks “o” in lexical ordering.
Solution 2 - Ruby on-Rails
Rails 4
Pay attention that from Rails 4 there are some new rules.
> Specifies a many-to-many relationship with another class. This associates two classes via an intermediate join table. Unless the join table is explicitly specified as an option, it is guessed using the lexical order of the class names. So a join between Developer and Project will give the default join table name of “developers_projects” because “D” precedes “P” alphabetically.
> Note that this precedence is calculated using the < operator for > String. This means that if the strings are of different lengths, and > the strings are equal when compared up to the shortest length, then > the longer string is considered of higher lexical precedence than the > shorter one. For example, one would expect the tables “paper_boxes” > and “papers” to generate a join table name of “papers_paper_boxes” > because of the length of the name “paper_boxes”, but it in fact > generates a join table name of “paper_boxes_papers”. Be aware of this > caveat, and use the custom :join_table option if you need to. > > If your tables share a common prefix, it will only appear once at the > beginning. For example, the tables “catalog_categories” and > “catalog_products” generate a join table name of > “catalog_categories_products”.
# alphabetically order
developers + projects --> developers_projects
# precedence is calculated with '<', lengthier strings have precedence
# if the string are equal compared to the shortest length
paper_boxes + papers --> paper_boxes_papers
# common prefix omitted
catalog_categories + catalog_products --> catalog_categories_products
Rails 5
The rule are still pretty the same. With Rails 5 we have a new helper for creating join tables with migrations:
class CreateDevelopersProjectsJoinTable < ActiveRecord::Migration[5.0]
def change
create_join_table :developers, :projects
end
end
Solution 3 - Ruby on-Rails
Join tables in Rails must be created in alphabetical order only. Keep this point in mind every time you create a join table.
For example, if you want to create a join table between project table and collaborator table you must name it like below.
Syntax: first_table_name(UNDERSCORE)second_table_name
# Names must be in alphabetical order and also in plural
# Decide which is your first table name based on the alphabetical order
Example: Creating Join Table between Project And Collaborator
Collaborator-Project
collaborators_projects
# you should name it like this; In alphabetical order with plural names
Example 2: Creating Join Table between BlogPost table and User Table
BlogPost-User
blog_posts_users # In alphabetical order with plural names
Solution 4 - Ruby on-Rails
The new create_join_table migration creates a join table that has no corresponding model, so no naming convention is required for the model name.
To access the join, you must declare has_and_belongs_to_many on the two tables, and access them through the association created.