vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

   1 module ActiveRecord
   2   module ConnectionAdapters # :nodoc:
   3     module SchemaStatements
   4       # Returns a Hash of mappings from the abstract data types to the native
   5       # database types.  See TableDefinition#column for details on the recognized
   6       # abstract data types.
   7       def native_database_types
   8         {}
   9       end
  10
  11       # This is the maximum length a table alias can be
  12       def table_alias_length
  13         255
  14       end
  15
  16       # Truncates a table alias according to the limits of the current adapter.
  17       def table_alias_for(table_name)
  18         table_name[0..table_alias_length-1].gsub(/\./, '_')
  19       end
  20
  21       # def tables(name = nil) end
  22
  23       def table_exists?(table_name)
  24         tables.include?(table_name.to_s)
  25       end
  26
  27       # Returns an array of indexes for the given table.
  28       # def indexes(table_name, name = nil) end
  29
  30       # Returns an array of Column objects for the table specified by +table_name+.
  31       # See the concrete implementation for details on the expected parameter values.
  32       def columns(table_name, name = nil) end
  33
  34       # Creates a new table with the name +table_name+. +table_name+ may either
  35       # be a String or a Symbol.
  36       #
  37       # There are two ways to work with +create_table+.  You can use the block
  38       # form or the regular form, like this:
  39       #
  40       # === Block form
  41       #  # create_table() passes a TableDefinition object to the block.
  42       #  # This form will not only create the table, but also columns for the
  43       #  # table.
  44       #  create_table(:suppliers) do |t|
  45       #    t.column :name, :string, :limit => 60
  46       #    # Other fields here
  47       #  end
  48       #
  49       # === Regular form
  50       #  # Creates a table called 'suppliers' with no columns.
  51       #  create_table(:suppliers)
  52       #  # Add a column to 'suppliers'.
  53       #  add_column(:suppliers, :name, :string, {:limit => 60})
  54       #
  55       # The +options+ hash can include the following keys:
  56       # [<tt>:id</tt>]
  57       #   Whether to automatically add a primary key column. Defaults to true.
  58       #   Join tables for +has_and_belongs_to_many+ should set <tt>:id => false</tt>.
  59       # [<tt>:primary_key</tt>]
  60       #   The name of the primary key, if one is to be added automatically.
  61       #   Defaults to +id+.
  62       # [<tt>:options</tt>]
  63       #   Any extra options you want appended to the table definition.
  64       # [<tt>:temporary</tt>]
  65       #   Make a temporary table.
  66       # [<tt>:force</tt>]
  67       #   Set to true to drop the table before creating it.
  68       #   Defaults to false.
  69       #
  70       # ===== Examples
  71       # ====== Add a backend specific option to the generated SQL (MySQL)
  72       #  create_table(:suppliers, :options => 'ENGINE=InnoDB DEFAULT CHARSET=utf8')
  73       # generates:
  74       #  CREATE TABLE suppliers (
  75       #    id int(11) DEFAULT NULL auto_increment PRIMARY KEY
  76       #  ) ENGINE=InnoDB DEFAULT CHARSET=utf8
  77       #
  78       # ====== Rename the primary key column
  79       #  create_table(:objects, :primary_key => 'guid') do |t|
  80       #    t.column :name, :string, :limit => 80
  81       #  end
  82       # generates:
  83       #  CREATE TABLE objects (
  84       #    guid int(11) DEFAULT NULL auto_increment PRIMARY KEY,
  85       #    name varchar(80)
  86       #  )
  87       #
  88       # ====== Do not add a primary key column
  89       #  create_table(:categories_suppliers, :id => false) do |t|
  90       #    t.column :category_id, :integer
  91       #    t.column :supplier_id, :integer
  92       #  end
  93       # generates:
  94       #  CREATE TABLE categories_suppliers (
  95       #    category_id int,
  96       #    supplier_id int
  97       #  )
  98       #
  99       # See also TableDefinition#column for details on how to create columns.
 100       def create_table(table_name, options = {})
 101         table_definition = TableDefinition.new(self)
 102         table_definition.primary_key(options[:primary_key] || Base.get_primary_key(table_name)) unless options[:id] == false
 103
 104         yield table_definition
 105
 106         if options[:force] && table_exists?(table_name)
 107           drop_table(table_name, options)
 108         end
 109
 110         create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE "
 111         create_sql << "#{quote_table_name(table_name)} ("
 112         create_sql << table_definition.to_sql
 113         create_sql << ") #{options[:options]}"
 114         execute create_sql
 115       end
 116
 117       # A block for changing columns in +table+.
 118       #
 119       # === Example
 120       #  # change_table() yields a Table instance
 121       #  change_table(:suppliers) do |t|
 122       #    t.column :name, :string, :limit => 60
 123       #    # Other column alterations here
 124       #  end
 125       #
 126       # ===== Examples
 127       # ====== Add a column
 128       #  change_table(:suppliers) do |t|
 129       #    t.column :name, :string, :limit => 60
 130       #  end
 131       #
 132       # ====== Add 2 integer columns
 133       #  change_table(:suppliers) do |t|
 134       #    t.integer :width, :height, :null => false, :default => 0
 135       #  end
 136       #
 137       # ====== Add created_at/updated_at columns
 138       #  change_table(:suppliers) do |t|
 139       #    t.timestamps
 140       #  end
 141       #
 142       # ====== Add a foreign key column
 143       #  change_table(:suppliers) do |t|
 144       #    t.references :company
 145       #  end
 146       #
 147       # Creates a <tt>company_id(integer)</tt> column
 148       #
 149       # ====== Add a polymorphic foreign key column
 150       #  change_table(:suppliers) do |t|
 151       #    t.belongs_to :company, :polymorphic => true
 152       #  end
 153       #
 154       # Creates <tt>company_type(varchar)</tt> and <tt>company_id(integer)</tt> columns
 155       #
 156       # ====== Remove a column
 157       #  change_table(:suppliers) do |t|
 158       #    t.remove :company
 159       #  end
 160       #
 161       # ====== Remove several columns
 162       #  change_table(:suppliers) do |t|
 163       #    t.remove :company_id
 164       #    t.remove :width, :height
 165       #  end
 166       #
 167       # ====== Remove an index
 168       #  change_table(:suppliers) do |t|
 169       #    t.remove_index :company_id
 170       #  end
 171       #
 172       # See also Table for details on
 173       # all of the various column transformation
 174       def change_table(table_name)
 175         yield Table.new(table_name, self)
 176       end
 177
 178       # Renames a table.
 179       # ===== Example
 180       #  rename_table('octopuses', 'octopi')
 181       def rename_table(table_name, new_name)
 182         raise NotImplementedError, "rename_table is not implemented"
 183       end
 184
 185       # Drops a table from the database.
 186       def drop_table(table_name, options = {})
 187         execute "DROP TABLE #{quote_table_name(table_name)}"
 188       end
 189
 190       # Adds a new column to the named table.
 191       # See TableDefinition#column for details of the options you can use.
 192       def add_column(table_name, column_name, type, options = {})
 193         add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
 194         add_column_options!(add_column_sql, options)
 195         execute(add_column_sql)
 196       end
 197
 198       # Removes the column(s) from the table definition.
 199       # ===== Examples
 200       #  remove_column(:suppliers, :qualification)
 201       #  remove_columns(:suppliers, :qualification, :experience)
 202       def remove_column(table_name, *column_names)
 203         column_names.flatten.each do |column_name|
 204           execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{quote_column_name(column_name)}"
 205         end
 206       end
 207       alias :remove_columns :remove_column
 208
 209       # Changes the column's definition according to the new options.
 210       # See TableDefinition#column for details of the options you can use.
 211       # ===== Examples
 212       #  change_column(:suppliers, :name, :string, :limit => 80)
 213       #  change_column(:accounts, :description, :text)
 214       def change_column(table_name, column_name, type, options = {})
 215         raise NotImplementedError, "change_column is not implemented"
 216       end
 217
 218       # Sets a new default value for a column.  If you want to set the default
 219       # value to +NULL+, you are out of luck.  You need to
 220       # DatabaseStatements#execute the appropriate SQL statement yourself.
 221       # ===== Examples
 222       #  change_column_default(:suppliers, :qualification, 'new')
 223       #  change_column_default(:accounts, :authorized, 1)
 224       def change_column_default(table_name, column_name, default)
 225         raise NotImplementedError, "change_column_default is not implemented"
 226       end
 227
 228       # Renames a column.
 229       # ===== Example
 230       #  rename_column(:suppliers, :description, :name)
 231       def rename_column(table_name, column_name, new_column_name)
 232         raise NotImplementedError, "rename_column is not implemented"
 233       end
 234
 235       # Adds a new index to the table.  +column_name+ can be a single Symbol, or
 236       # an Array of Symbols.
 237       #
 238       # The index will be named after the table and the first column name,
 239       # unless you pass <tt>:name</tt> as an option.
 240       #
 241       # When creating an index on multiple columns, the first column is used as a name
 242       # for the index. For example, when you specify an index on two columns
 243       # [<tt>:first</tt>, <tt>:last</tt>], the DBMS creates an index for both columns as well as an
 244       # index for the first column <tt>:first</tt>. Using just the first name for this index
 245       # makes sense, because you will never have to create a singular index with this
 246       # name.
 247       #
 248       # ===== Examples
 249       # ====== Creating a simple index
 250       #  add_index(:suppliers, :name)
 251       # generates
 252       #  CREATE INDEX suppliers_name_index ON suppliers(name)
 253       # ====== Creating a unique index
 254       #  add_index(:accounts, [:branch_id, :party_id], :unique => true)
 255       # generates
 256       #  CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)
 257       # ====== Creating a named index
 258       #  add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party')
 259       # generates
 260       #  CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)
 261       def add_index(table_name, column_name, options = {})
 262         column_names = Array(column_name)
 263         index_name   = index_name(table_name, :column => column_names)
 264
 265         if Hash === options # legacy support, since this param was a string
 266           index_type = options[:unique] ? "UNIQUE" : ""
 267           index_name = options[:name] || index_name
 268         else
 269           index_type = options
 270         end
 271         quoted_column_names = column_names.map { |e| quote_column_name(e) }.join(", ")
 272         execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{quoted_column_names})"
 273       end
 274
 275       # Remove the given index from the table.
 276       #
 277       # Remove the suppliers_name_index in the suppliers table.
 278       #   remove_index :suppliers, :name
 279       # Remove the index named accounts_branch_id_index in the accounts table.
 280       #   remove_index :accounts, :column => :branch_id
 281       # Remove the index named accounts_branch_id_party_id_index in the accounts table.
 282       #   remove_index :accounts, :column => [:branch_id, :party_id]
 283       # Remove the index named by_branch_party in the accounts table.
 284       #   remove_index :accounts, :name => :by_branch_party
 285       def remove_index(table_name, options = {})
 286         execute "DROP INDEX #{quote_column_name(index_name(table_name, options))} ON #{table_name}"
 287       end
 288
 289       def index_name(table_name, options) #:nodoc:
 290         if Hash === options # legacy support
 291           if options[:column]
 292             "index_#{table_name}_on_#{Array(options[:column]) * '_and_'}"
 293           elsif options[:name]
 294             options[:name]
 295           else
 296             raise ArgumentError, "You must specify the index name"
 297           end
 298         else
 299           index_name(table_name, :column => options)
 300         end
 301       end
 302
 303       # Returns a string of <tt>CREATE TABLE</tt> SQL statement(s) for recreating the
 304       # entire structure of the database.
 305       def structure_dump
 306       end
 307
 308       def dump_schema_information #:nodoc:
 309         sm_table = ActiveRecord::Migrator.schema_migrations_table_name
 310         migrated = select_values("SELECT version FROM #{sm_table}")
 311         migrated.map { |v| "INSERT INTO #{sm_table} (version) VALUES ('#{v}');" }.join("\n\n")
 312       end
 313
 314       # Should not be called normally, but this operation is non-destructive.
 315       # The migrations module handles this automatically.
 316       def initialize_schema_migrations_table
 317         sm_table = ActiveRecord::Migrator.schema_migrations_table_name
 318
 319         unless tables.detect { |t| t == sm_table }
 320           create_table(sm_table, :id => false) do |schema_migrations_table|
 321             schema_migrations_table.column :version, :string, :null => false
 322           end
 323           add_index sm_table, :version, :unique => true,
 324             :name => 'unique_schema_migrations'
 325
 326           # Backwards-compatibility: if we find schema_info, assume we've
 327           # migrated up to that point:
 328           si_table = Base.table_name_prefix + 'schema_info' + Base.table_name_suffix
 329
 330           if tables.detect { |t| t == si_table }
 331
 332             old_version = select_value("SELECT version FROM #{quote_table_name(si_table)}").to_i
 333             assume_migrated_upto_version(old_version)
 334             drop_table(si_table)
 335           end
 336         end
 337       end
 338
 339       def assume_migrated_upto_version(version)
 340         version = version.to_i
 341         sm_table = quote_table_name(ActiveRecord::Migrator.schema_migrations_table_name)
 342
 343         migrated = select_values("SELECT version FROM #{sm_table}").map(&:to_i)
 344         versions = Dir['db/migrate/[0-9]*_*.rb'].map do |filename|
 345           filename.split('/').last.split('_').first.to_i
 346         end
 347
 348         unless migrated.include?(version)
 349           execute "INSERT INTO #{sm_table} (version) VALUES ('#{version}')"
 350         end
 351
 352         inserted = Set.new
 353         (versions - migrated).each do |v|
 354           if inserted.include?(v)
 355             raise "Duplicate migration #{v}. Please renumber your migrations to resolve the conflict."
 356           elsif v < version
 357             execute "INSERT INTO #{sm_table} (version) VALUES ('#{v}')"
 358             inserted << v
 359           end
 360         end
 361       end
 362
 363       def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
 364         if native = native_database_types[type]
 365           column_type_sql = (native.is_a?(Hash) ? native[:name] : native).dup
 366
 367           if type == :decimal # ignore limit, use precision and scale
 368             scale ||= native[:scale]
 369
 370             if precision ||= native[:precision]
 371               if scale
 372                 column_type_sql << "(#{precision},#{scale})"
 373               else
 374                 column_type_sql << "(#{precision})"
 375               end
 376             elsif scale
 377               raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale if specified"
 378             end
 379
 380           elsif (type != :primary_key) && (limit ||= native.is_a?(Hash) && native[:limit])
 381             column_type_sql << "(#{limit})"
 382           end
 383
 384           column_type_sql
 385         else
 386           type
 387         end
 388       end
 389
 390       def add_column_options!(sql, options) #:nodoc:
 391         sql << " DEFAULT #{quote(options[:default], options[:column])}" if options_include_default?(options)
 392         # must explicitly check for :null to allow change_column to work on migrations
 393         if options[:null] == false
 394           sql << " NOT NULL"
 395         end
 396       end
 397
 398       # SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause.
 399       # Both PostgreSQL and Oracle overrides this for custom DISTINCT syntax.
 400       #
 401       #   distinct("posts.id", "posts.created_at desc")
 402       def distinct(columns, order_by)
 403         "DISTINCT #{columns}"
 404       end
 405
 406       # ORDER BY clause for the passed order option.
 407       # PostgreSQL overrides this due to its stricter standards compliance.
 408       def add_order_by_for_association_limiting!(sql, options)
 409         sql << " ORDER BY #{options[:order]}"
 410       end
 411
 412       # Adds timestamps (created_at and updated_at) columns to the named table.
 413       # ===== Examples
 414       #  add_timestamps(:suppliers)
 415       def add_timestamps(table_name)
 416         add_column table_name, :created_at, :datetime
 417         add_column table_name, :updated_at, :datetime
 418       end
 419
 420       # Removes the timestamp columns (created_at and updated_at) from the table definition.
 421       # ===== Examples
 422       #  remove_timestamps(:suppliers)
 423       def remove_timestamps(table_name)
 424         remove_column table_name, :updated_at
 425         remove_column table_name, :created_at
 426       end
 427
 428       protected
 429         def options_include_default?(options)
 430           options.include?(:default) && !(options[:null] == false && options[:default].nil?)
 431         end
 432     end
 433   end
 434 end