Module: ActiveRecord::ConnectionAdapters::SchemaStatements

Included in:
AbstractAdapter
Defined in:
lib/active_record/connection_adapters/abstract/schema_statements.rb

Instance Method Summary collapse

Instance Method Details

#add_column(table_name, column_name, type, options = {}) ⇒ Object

Adds a new column to the named table. See TableDefinition#column for details of the options you can use.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 245

def add_column(table_name, column_name, type, options = {})
  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])}"
  add_column_options!(add_column_sql, options)
  execute(add_column_sql)
end

#add_column_options!(sql, options) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 496

def add_column_options!(sql, options) #:nodoc:
  sql << " DEFAULT #{quote(options[:default], options[:column])}" if options_include_default?(options)
  # must explicitly check for :null to allow change_column to work on migrations
  if options[:null] == false
    sql << " NOT NULL"
  end
end

#add_index(table_name, column_name, options = {}) ⇒ Object

Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.

The index will be named after the table and the first column name, unless you pass :name as an option.

When creating an index on multiple columns, the first column is used as a name for the index. For example, when you specify an index on two columns [:first, :last], the DBMS creates an index for both columns as well as an index for the first column :first. Using just the first name for this index makes sense, because you will never have to create a singular index with this name.

Examples
Creating a simple index

add_index(:suppliers, :name) generates CREATE INDEX suppliers_name_index ON suppliers(name)

Creating a unique index

add_index(:accounts, [:branch_id, :party_id], :unique => true) generates CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)

Creating a named index

add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party') generates CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)

Creating an index with specific key length

add_index(:accounts, :name, :name => 'by_name', :length => 10) generates CREATE INDEX by_name ON accounts(name(10))

add_index(:accounts, [:name, :surname], :name => 'by_name_surname', :length => => 10, :surname => 15) generates CREATE INDEX by_name_surname ON accounts(name(10), surname(15))

Note: SQLite doesn't support index length



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 329

def add_index(table_name, column_name, options = {})
  column_names = Array.wrap(column_name)
  index_name   = index_name(table_name, :column => column_names)

  if Hash === options # legacy support, since this param was a string
    index_type = options[:unique] ? "UNIQUE" : ""
    index_name = options[:name].to_s if options.key?(:name)
  else
    index_type = options
  end

  if index_name.length > index_name_length
    raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters"
  end
  if index_name_exists?(table_name, index_name, false)
    raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' already exists"
  end
  quoted_column_names = quoted_columns_for_index(column_names, options).join(", ")

  execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{quoted_column_names})"
end

#add_timestamps(table_name) ⇒ Object

Adds timestamps (created_at and updated_at) columns to the named table.

Examples

add_timestamps(:suppliers)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 515

def add_timestamps(table_name)
  add_column table_name, :created_at, :datetime
  add_column table_name, :updated_at, :datetime
end

#assume_migrated_upto_version(version, migrations_path = ActiveRecord::Migrator.migrations_path) ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 445

def assume_migrated_upto_version(version, migrations_path = ActiveRecord::Migrator.migrations_path)
  version = version.to_i
  sm_table = quote_table_name(ActiveRecord::Migrator.schema_migrations_table_name)

  migrated = select_values("SELECT version FROM #{sm_table}").map { |v| v.to_i }
  versions = Dir["#{migrations_path}/[0-9]*_*.rb"].map do |filename|
    filename.split('/').last.split('_').first.to_i
  end

  unless migrated.include?(version)
    execute "INSERT INTO #{sm_table} (version) VALUES ('#{version}')"
  end

  inserted = Set.new
  (versions - migrated).each do |v|
    if inserted.include?(v)
      raise "Duplicate migration #{v}. Please renumber your migrations to resolve the conflict."
    elsif v < version
      execute "INSERT INTO #{sm_table} (version) VALUES ('#{v}')"
      inserted << v
    end
  end
end

#change_column(table_name, column_name, type, options = {}) ⇒ Object

Changes the column's definition according to the new options. See TableDefinition#column for details of the options you can use.

Examples

change_column(:suppliers, :name, :string, :limit => 80) change_column(:accounts, :description, :text)

Raises:

  • (NotImplementedError) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 268

def change_column(table_name, column_name, type, options = {})
  raise NotImplementedError, "change_column is not implemented"
end

#change_column_default(table_name, column_name, default) ⇒ Object

Sets a new default value for a column. If you want to set the default value to NULL, you are out of luck. You need to DatabaseStatements#execute the appropriate SQL statement yourself.

Examples

change_column_default(:suppliers, :qualification, 'new') change_column_default(:accounts, :authorized, 1)

Raises:

  • (NotImplementedError) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 278

def change_column_default(table_name, column_name, default)
  raise NotImplementedError, "change_column_default is not implemented"
end

#change_table(table_name) {|Table.new(table_name, self)| ... } ⇒ Object

A block for changing columns in table.

Example

change_table() yields a Table instance

change_table(:suppliers) do |t| t.column :name, :string, :limit => 60

Other column alterations here

end

Examples
Add a column

change_table(:suppliers) do |t| t.column :name, :string, :limit => 60 end

Add 2 integer columns

change_table(:suppliers) do |t| t.integer :width, :height, :null => false, :default => 0 end

Add created_at/updated_at columns

change_table(:suppliers) do |t| t.timestamps end

Add a foreign key column

change_table(:suppliers) do |t| t.references :company end

Creates a company_id(integer) column

Add a polymorphic foreign key column

change_table(:suppliers) do |t| t.belongs_to :company, :polymorphic => true end

Creates company_type(varchar) and company_id(integer) columns

Remove a column

change_table(:suppliers) do |t| t.remove :company end

Remove several columns

change_table(:suppliers) do |t| t.remove :company_id t.remove :width, :height end

Remove an index

change_table(:suppliers) do |t| t.remove_index :company_id end

See also Table for details on all of the various column transformation

Yields:

  • (Table.new(table_name, self)) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 227

def change_table(table_name)
  yield Table.new(table_name, self)
end

#column_exists?(table_name, column_name, type = nil, options = {}) ⇒ Boolean

Checks to see if a column exists in a given table.

Examples

Check a column exists

column_exists?(:suppliers, :name)

Check a column exists of a particular type

column_exists?(:suppliers, :name, :string)

Check a column exists with a specific definition

column_exists?(:suppliers, :name, :string, :limit => 100)

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 66

def column_exists?(table_name, column_name, type = nil, options = {})
  columns(table_name).any?{ |c| c.name == column_name.to_s &&
                                (!type                 || c.type == type) &&
                                (!options[:limit]      || c.limit == options[:limit]) &&
                                (!options[:precision]  || c.precision == options[:precision]) &&
                                (!options[:scale]      || c.scale == options[:scale]) }
end

#columns(table_name, name = nil) ⇒ Object

Returns an array of Column objects for the table specified by table_name. See the concrete implementation for details on the expected parameter values.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 53

def columns(table_name, name = nil) end

#create_table(table_name, options = {}) {|table_definition| ... } ⇒ Object

Creates a new table with the name table_name. table_name may either be a String or a Symbol.

There are two ways to work with create_table. You can use the block form or the regular form, like this:

Block form

create_table() passes a TableDefinition object to the block.

This form will not only create the table, but also columns for the

table.

create_table(:suppliers) do |t| t.column :name, :string, :limit => 60

Other fields here

end

Block form, with shorthand

You can also use the column types as method calls, rather than calling the column method.

create_table(:suppliers) do |t| t.string :name, :limit => 60

Other fields here

end

Regular form

Creates a table called 'suppliers' with no columns.

create_table(:suppliers)

Add a column to 'suppliers'.

add_column(:suppliers, :name, :string, => 60)

The options hash can include the following keys: [:id] Whether to automatically add a primary key column. Defaults to true. Join tables for has_and_belongs_to_many should set it to false. [:primary_key] The name of the primary key, if one is to be added automatically. Defaults to id. If :id is false this option is ignored.

Also note that this just sets the primary key in the table. You additionally
need to configure the primary key in the model via the +set_primary_key+ macro.
Models do NOT auto-detect the primary key from their table definition.

[:options] Any extra options you want appended to the table definition. [:temporary] Make a temporary table. [:force] Set to true to drop the table before creating it. Defaults to false.

Examples
Add a backend specific option to the generated SQL (MySQL)

create_table(:suppliers, :options => 'ENGINE=InnoDB DEFAULT CHARSET=utf8') generates: CREATE TABLE suppliers ( id int(11) DEFAULT NULL auto_increment PRIMARY KEY ) ENGINE=InnoDB DEFAULT CHARSET=utf8

Rename the primary key column

create_table(:objects, :primary_key => 'guid') do |t| t.column :name, :string, :limit => 80 end generates: CREATE TABLE objects ( guid int(11) DEFAULT NULL auto_increment PRIMARY KEY, name varchar(80) )

Do not add a primary key column

create_table(:categories_suppliers, :id => false) do |t| t.column :category_id, :integer t.column :supplier_id, :integer end generates: CREATE TABLE categories_suppliers ( category_id int, supplier_id int )

See also TableDefinition#column for details on how to create columns.

Yields:

  • (table_definition) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 153

def create_table(table_name, options = {})
  table_definition = TableDefinition.new(self)
  table_definition.primary_key(options[:primary_key] || Base.get_primary_key(table_name.to_s.singularize)) unless options[:id] == false

  yield table_definition if block_given?

  if options[:force] && table_exists?(table_name)
    drop_table(table_name, options)
  end

  create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE "
  create_sql << "#{quote_table_name(table_name)} ("
  create_sql << table_definition.to_sql
  create_sql << ") #{options[:options]}"
  execute create_sql
end

#distinct(columns, order_by) ⇒ Object

SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause. Both PostgreSQL and Oracle overrides this for custom DISTINCT syntax.

distinct("posts.id", "posts.created_at desc")


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 508

def distinct(columns, order_by)
  "DISTINCT #{columns}"
end

#drop_table(table_name, options = {}) ⇒ Object

Drops a table from the database.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 239

def drop_table(table_name, options = {})
  execute "DROP TABLE #{quote_table_name(table_name)}"
end

#dump_schema_information ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 414

def dump_schema_information #:nodoc:
  sm_table = ActiveRecord::Migrator.schema_migrations_table_name
  migrated = select_values("SELECT version FROM #{sm_table}")
  migrated.map { |v| "INSERT INTO #{sm_table} (version) VALUES ('#{v}');" }.join("\n\n")
end

#index_exists?(table_name, column_name, options = {}) ⇒ Boolean

Checks to see if an index exists on a table for a given index definition

Examples

Check an index exists

index_exists?(:suppliers, :company_id)

Check an index on multiple columns exists

index_exists?(:suppliers, [:company_id, :company_type])

Check a unique index exists

index_exists?(:suppliers, :company_id, :unique => true)

Check an index with a custom name exists

index_exists?(:suppliers, :company_id, :name => "idx_company_id"

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 41

def index_exists?(table_name, column_name, options = {})
  column_names = Array.wrap(column_name)
  index_name = options.key?(:name) ? options[:name].to_s : index_name(table_name, :column => column_names)
  if options[:unique]
    indexes(table_name).any?{ |i| i.unique && i.name == index_name }
  else
    indexes(table_name).any?{ |i| i.name == index_name }
  end
end

#index_name(table_name, options) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 385

def index_name(table_name, options) #:nodoc:
  if Hash === options # legacy support
    if options[:column]
      "index_#{table_name}_on_#{Array.wrap(options[:column]) * '_and_'}"
    elsif options[:name]
      options[:name]
    else
      raise ArgumentError, "You must specify the index name"
    end
  else
    index_name(table_name, :column => options)
  end
end

#index_name_exists?(table_name, index_name, default) ⇒ Boolean

Verify the existence of an index with a given name.

The default argument is returned if the underlying implementation does not define the indexes method, as there's no way to determine the correct answer in that case.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 403

def index_name_exists?(table_name, index_name, default)
  return default unless respond_to?(:indexes)
  index_name = index_name.to_s
  indexes(table_name).detect { |i| i.name == index_name }
end

#initialize_schema_migrations_table ⇒ Object

Should not be called normally, but this operation is non-destructive. The migrations module handles this automatically.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 422

def initialize_schema_migrations_table
  sm_table = ActiveRecord::Migrator.schema_migrations_table_name

  unless table_exists?(sm_table)
    create_table(sm_table, :id => false) do |schema_migrations_table|
      schema_migrations_table.column :version, :string, :null => false
    end
    add_index sm_table, :version, :unique => true,
      :name => "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"

    # Backwards-compatibility: if we find schema_info, assume we've
    # migrated up to that point:
    si_table = Base.table_name_prefix + 'schema_info' + Base.table_name_suffix

    if table_exists?(si_table)

      old_version = select_value("SELECT version FROM #{quote_table_name(si_table)}").to_i
      assume_migrated_upto_version(old_version)
      drop_table(si_table)
    end
  end
end

#native_database_types ⇒ Object

Returns a Hash of mappings from the abstract data types to the native database types. See TableDefinition#column for details on the recognized abstract data types.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 9

def native_database_types
  {}
end

#remove_column(table_name, *column_names) ⇒ Object Also known as: remove_columns

Removes the column(s) from the table definition.

Examples

remove_column(:suppliers, :qualification) remove_columns(:suppliers, :qualification, :experience)

Raises:

  • (ArgumentError) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 255

def remove_column(table_name, *column_names)
  raise ArgumentError.new("You must specify at least one column name.  Example: remove_column(:people, :first_name)") if column_names.empty?
  column_names.flatten.each do |column_name|
    execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{quote_column_name(column_name)}"
  end
end

#remove_index(table_name, options = {}) ⇒ Object

Remove the given index from the table.

Remove the suppliers_name_index in the suppliers table. remove_index :suppliers, :name Remove the index named accounts_branch_id_index in the accounts table. remove_index :accounts, :column => :branch_id Remove the index named accounts_branch_id_party_id_index in the accounts table. remove_index :accounts, :column => [:branch_id, :party_id] Remove the index named by_branch_party in the accounts table. remove_index :accounts, :name => :by_branch_party



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 361

def remove_index(table_name, options = {})
  index_name = index_name(table_name, options)
  unless index_name_exists?(table_name, index_name, true)
    raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' does not exist"
  end
  remove_index!(table_name, index_name)
end

#remove_index!(table_name, index_name) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 369

def remove_index!(table_name, index_name) #:nodoc:
  execute "DROP INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)}"
end

#remove_timestamps(table_name) ⇒ Object

Removes the timestamp columns (created_at and updated_at) from the table definition.

Examples

remove_timestamps(:suppliers)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 523

def remove_timestamps(table_name)
  remove_column table_name, :updated_at
  remove_column table_name, :created_at
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object

Renames a column.

Example

rename_column(:suppliers, :description, :name)

Raises:

  • (NotImplementedError) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 285

def rename_column(table_name, column_name, new_column_name)
  raise NotImplementedError, "rename_column is not implemented"
end

#rename_index(table_name, old_name, new_name) ⇒ Object

Rename an index.

Rename the index_people_on_last_name index to index_users_on_last_name rename_index :people, 'index_people_on_last_name', 'index_users_on_last_name'



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 377

def rename_index(table_name, old_name, new_name)
  # this is a naive implementation; some DBs may support this more efficiently (Postgres, for instance)
  old_index_def = indexes(table_name).detect { |i| i.name == old_name }
  return unless old_index_def
  remove_index(table_name, :name => old_name)
  add_index(table_name, old_index_def.columns, :name => new_name, :unique => old_index_def.unique)
end

#rename_table(table_name, new_name) ⇒ Object

Renames a table.

Example

rename_table('octopuses', 'octopi')

Raises:

  • (NotImplementedError) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 234

def rename_table(table_name, new_name)
  raise NotImplementedError, "rename_table is not implemented"
end

#structure_dump ⇒ Object

Returns a string of CREATE TABLE SQL statement(s) for recreating the entire structure of the database.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 411

def structure_dump
end

#table_alias_for(table_name) ⇒ Object

Truncates a table alias according to the limits of the current adapter.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 14

def table_alias_for(table_name)
  table_name[0..table_alias_length-1].gsub(/\./, '_')
end

#table_exists?(table_name) ⇒ Boolean

def tables(name = nil) end

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 20

def table_exists?(table_name)
  tables.include?(table_name.to_s)
end

#type_to_sql(type, limit = nil, precision = nil, scale = nil) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 469

def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
  if native = native_database_types[type]
    column_type_sql = (native.is_a?(Hash) ? native[:name] : native).dup

    if type == :decimal # ignore limit, use precision and scale
      scale ||= native[:scale]

      if precision ||= native[:precision]
        if scale
          column_type_sql << "(#{precision},#{scale})"
        else
          column_type_sql << "(#{precision})"
        end
      elsif scale
        raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale if specified"
      end

    elsif (type != :primary_key) && (limit ||= native.is_a?(Hash) && native[:limit])
      column_type_sql << "(#{limit})"
    end

    column_type_sql
  else
    type
  end
end