Module: ActiveRecord::ConnectionAdapters::MysqlAdapterForeignKeyMethods

Included in:
Mysql2Adapter, MysqlAdapter
Defined in:
lib/foreign_key_saver/foreign_key_saver_patches.rb

Overview

common to mysql & mysql2

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.columns_from_sql(column_list_sql) ⇒ Object 



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# File 'lib/foreign_key_saver/foreign_key_saver_patches.rb', line 123

def self.columns_from_sql(column_list_sql)
  column_list_sql.scan(/`([^`]+)`/).collect(&:first)
end

.constraints_from_sql(create_table_sql) ⇒ Object 



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# File 'lib/foreign_key_saver/foreign_key_saver_patches.rb', line 116

def self.constraints_from_sql(create_table_sql)
  # the clauses look like this: CONSTRAINT `ab` FOREIGN KEY (`ac`, `bc`) REFERENCES `parent` (`a`, `b`) ON DELETE SET NULL ON UPDATE CASCADE
  create_table_sql.scan(/CONSTRAINT `([^`]+)` FOREIGN KEY \((`(?:[^`]+)`(?:, `(?:[^`]+)`)*)\) REFERENCES `([^`]+)` \((`(?:[^`]+)`(?:, `(?:[^`]+)`)*)\)(?: ON DELETE (CASCADE|RESTRICT|NO ACTION|SET NULL|SET DEFAULT))?(?: ON UPDATE (CASCADE|RESTRICT|NO ACTION|SET NULL|SET DEFAULT))?/).collect do |capture|
    ForeignKeyConstraint.new(capture[0], columns_from_sql(capture[1]), capture[2], columns_from_sql(capture[3]), capture[5], capture[4])
  end
end

Instance Method Details

#foreign_key_constraints_on(table_name) ⇒ Object 



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# File 'lib/foreign_key_saver/foreign_key_saver_patches.rb', line 112

def foreign_key_constraints_on(table_name)
  self.class.constraints_from_sql(select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"])
end

#remove_foreign_key_constraint(table_name, constraint) ⇒ Object 



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# File 'lib/foreign_key_saver/foreign_key_saver_patches.rb', line 98

def remove_foreign_key_constraint(table_name, constraint)
  execute "ALTER TABLE #{quote_table_name(table_name)} DROP FOREIGN KEY #{quote_column_name(constraint)}"
end

#remove_foreign_key_constraints_referencing(table_name) ⇒ Object 



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# File 'lib/foreign_key_saver/foreign_key_saver_patches.rb', line 102

def remove_foreign_key_constraints_referencing(table_name)
  select_rows(
          "SELECT DISTINCT TABLE_NAME, CONSTRAINT_NAME" +
          "  FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE" +
          " WHERE REFERENCED_TABLE_SCHEMA = SCHEMA()" +
          "   AND REFERENCED_TABLE_NAME = #{quote(table_name)}").each do |table_name, constraint_name|
    remove_foreign_key_constraint(table_name, constraint_name)
  end
end