FriendlyFk

Uses child and parent table names plus the referencing column to give every foreign key a readable name by default — e.g. fk_child_table__parent_table__parent_id. Folding the column in keeps names unique even when several foreign keys connect the same table pair.

If the generated name would exceed the database's identifier limit, the column part is replaced with a short deterministic hash (fk_child_table__parent_table__<hash>). If even the table-pair prefix is too long for the limit, the whole name falls back to fk_friendly_<hash>.

Installation

Add this line to your application's Gemfile:

gem 'friendly_fk'

And then execute:

$ bundle

Requirements

• Ruby >= 2.7
• ActiveRecord >= 6.1, < 8.2

Usage

Just use the conventional add_foreign_key call in your migrations — FriendlyFk fills in the name automatically:

add_foreign_key :comments, :posts
# constraint name: fk_comments__posts__post_id

add_foreign_key :comments, :users, column: :author_id
# constraint name: fk_comments__users__author_id

Because the column is part of the name, multiple foreign keys between the same pair of tables get distinct names instead of colliding:

add_foreign_key :messages, :users, column: :sender_id
# constraint name: fk_messages__users__sender_id
add_foreign_key :messages, :users, column: :recipient_id
# constraint name: fk_messages__users__recipient_id

Pass an explicit name: to opt out of the generated name entirely:

add_foreign_key :comments, :posts, name: 'my_custom_fk'