Class: DeclareSchema::Model::ForeignKeyDefinition

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/declare_schema/model/foreign_key_definition.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(foreign_key_column, constraint_name: nil, child_table_name: nil, parent_class_name: nil, parent_table_name: nil, dependent: nil) ⇒ ForeignKeyDefinition

Caller needs to pass either constraint_name or child_table_name, and either parent_class_name or parent_table_name.



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 14

def initialize(foreign_key_column, constraint_name: nil, child_table_name: nil, parent_class_name: nil, parent_table_name: nil, dependent: nil)
  @foreign_key_column = foreign_key_column&.to_s or raise ArgumentError "foreign key must not be empty: #{foreign_key_column.inspect}"
  @constraint_name = constraint_name&.to_s.presence || ::DeclareSchema::Model::IndexDefinition.default_index_name(child_table_name, [@foreign_key_column])
  @child_table_name = child_table_name&.to_s or raise ArgumentError, "child_table_name must not be nil"
  @parent_class_name =
    case parent_class_name
    when String, Symbol
      parent_class_name.to_s
    when Class
      @parent_class = parent_class_name
      @parent_class.name
    when nil
      @foreign_key_column.sub(/_id\z/, '').camelize
    end
  @parent_table_name = parent_table_name
  dependent.in?([nil, :delete]) or raise ArgumentError, "dependent: must be nil or :delete"
  @dependent = dependent
end

Instance Attribute Details

#child_table_name ⇒ Object (readonly)

Returns the value of attribute child_table_name.



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 10

def child_table_name
  @child_table_name
end

#constraint_name ⇒ Object (readonly)

Returns the value of attribute constraint_name.



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 10

def constraint_name
  @constraint_name
end

#dependent ⇒ Object (readonly)

Returns the value of attribute dependent.



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 10

def dependent
  @dependent
end

#foreign_key_column ⇒ Object (readonly)

Returns the value of attribute foreign_key_column.



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 10

def foreign_key_column
  @foreign_key_column
end

#parent_class_name ⇒ Object (readonly)

Returns the value of attribute parent_class_name.



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 10

def parent_class_name
  @parent_class_name
end

Class Method Details

.for_table(child_table_name, connection, dependent: nil) ⇒ Object 



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 34

def for_table(child_table_name, connection, dependent: nil)
  show_create_table = connection.select_rows("show create table #{connection.quote_table_name(child_table_name)}").first.last
  constraints = show_create_table.split("\n").map { |line| line.strip if line['CONSTRAINT'] }.compact

  constraints.map do |fkc|
    constraint_name, foreign_key_column, parent_table_name = fkc.match(/CONSTRAINT `([^`]*)` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)`/).captures
    dependent_value = :delete if dependent || fkc['ON DELETE CASCADE']

    new(foreign_key_column,
        constraint_name: constraint_name,
        child_table_name: child_table_name,
        parent_table_name: parent_table_name,
        dependent: dependent_value)
  end
end

Instance Method Details

#<=>(rhs) ⇒ Object 



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 55

def <=>(rhs)
  key <=> rhs.key
end

#equivalent?(rhs) ⇒ Boolean

Returns:



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 61

def equivalent?(rhs)
  self == rhs
end

#hash ⇒ Object 



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 75

def hash
  key.hash
end

#key ⇒ Object 



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 51

def key
  @key ||= [@child_table_name, @foreign_key_column, @dependent].freeze
end

#parent_class ⇒ Object

returns the parent class as a Class object lazy loaded so that we don’t require the parent class until we need it



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 67

def parent_class
  @parent_class ||= @parent_class_name.constantize
end

#parent_table_name ⇒ Object 



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# File 'lib/declare_schema/model/foreign_key_definition.rb', line 71

def parent_table_name
  @parent_table_name ||= parent_class.table_name
end