class CQL::ForeignKey

Reference < Object

The CQL::ForeignKey class defines a foreign key constraint between two tables. It allows you to specify the columns, referenced table, and the actions to be taken on DELETE or UPDATE.

Example: Creating a Foreign Key

schema.build do
  table :users do
    column :id, Int32, primary: true
    column :name, String
  end
end

table :posts do
  column :id, Int32, primary: true
  column :user_id, Int32, foreign_key: true
end

Constructors

def new(columns : Array(Symbol), references : Symbol, on_delete : Symbol = :restrict, on_update : Symbol = :restrict)

Creates a new foreign key constraint.

• @param columns [Array(Symbol)] The columns in the current table.

• @param references [Symbol] The referenced table.

• @param on_delete [Symbol] Action to take on delete (:restrict, :cascade, :set_null).

• @param on_update [Symbol] Action to take on update (:restrict, :cascade, :set_null).

• @return [ForeignKey] The created foreign key object.

Example:

foreign_key = CQL::ForeignKey.new([:user_id], :users, on_delete: :cascade)

Methods

def on_delete(action : Symbol)

Sets the action to take when a referenced record is deleted.

• @param action [Symbol] The action (:restrict, :cascade, :set_null).

• @return [ForeignKey] The updated foreign key object.

Example:

foreign_key.on_delete(:cascade)

def on_update(action : Symbol)

Sets the action to take when a referenced record is updated.

• @param action [Symbol] The action (:restrict, :cascade, :set_null).

• @return [ForeignKey] The updated foreign key object.

Example:

foreign_key.on_update(:restrict)