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ActiveRecord::ConnectionAdapters::SchemaStatements

Public Instance Methods

add_column(table_name, column_name, type, options = {}) click to toggle source

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

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 187
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_index(table_name, column_name, options = {}) click to toggle source

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 => {:name => 10, :surname => 15})

generates

CREATE INDEX by_name_surname ON accounts(name(10), surname(15))

Note: SQLite doesn't support index length

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 271
def add_index(table_name, column_name, options = {})
  column_names = Array(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[:name]
  else
    index_type = options
  end

  if index_name.length > index_name_length
    @logger.warn("Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters. Skipping.")
    return
  end
  if index_exists?(table_name, index_name, false)
    @logger.warn("Index name '#{index_name}' on table '#{table_name}' already exists. Skipping.")
    return
  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_order_by_for_association_limiting!(sql, options) click to toggle source

ORDER BY clause for the passed order option. PostgreSQL overrides this due to its stricter standards compliance.

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 459
def add_order_by_for_association_limiting!(sql, options)
  sql << " ORDER BY #{options[:order]}"
end
add_timestamps(table_name) click to toggle source

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

Examples
add_timestamps(:suppliers)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 466
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) click to toggle source
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 390
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(&: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 = {}) click to toggle source

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)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 210
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) click to toggle source

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)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 220
def change_column_default(table_name, column_name, default)
  raise NotImplementedError, "change_column_default is not implemented"
end
change_table(table_name) click to toggle source

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

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 169
def change_table(table_name)
  yield Table.new(table_name, self)
end
columns(table_name, name = nil) click to toggle source

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

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 27
def columns(table_name, name = nil) end
create_table(table_name, options = {}) click to toggle source

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

Regular form

# Creates a table called 'suppliers' with no columns.
create_table(:suppliers)
# Add a column to 'suppliers'.
add_column(:suppliers, :name, :string, {:limit => 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 :id => false.

:primary_key

The name of the primary key, if one is to be added automatically. Defaults to id.

: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.

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 95
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) click to toggle source

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")
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 453
def distinct(columns, order_by)
  "DISTINCT #{columns}"
end
drop_table(table_name, options = {}) click to toggle source

Drops a table from the database.

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 181
def drop_table(table_name, options = {})
  execute "DROP TABLE #{quote_table_name(table_name)}"
end
index_exists?(table_name, index_name, default) click to toggle source

Verify the existence of an index.

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.

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 348
def index_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() click to toggle source

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

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 367
def initialize_schema_migrations_table
  sm_table = ActiveRecord::Migrator.schema_migrations_table_name

  unless tables.detect { |t| t == 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 tables.detect { |t| t == 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() click to toggle source

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.

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 7
def native_database_types
  {}
end
remove_column(table_name, *column_names) click to toggle source

Removes the column(s) from the table definition.

Examples
remove_column(:suppliers, :qualification)
remove_columns(:suppliers, :qualification, :experience)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 197
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
Also aliased as: remove_columns
remove_columns(table_name, *column_names) click to toggle source
Alias for: remove_column
remove_index(table_name, options = {}) click to toggle source

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
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 305
def remove_index(table_name, options = {})
  index_name = index_name(table_name, options)
  unless index_exists?(table_name, index_name, true)
    @logger.warn("Index name '#{index_name}' on table '#{table_name}' does not exist. Skipping.")
    return
  end
  remove_index!(table_name, index_name)
end
remove_timestamps(table_name) click to toggle source

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

Examples
remove_timestamps(:suppliers)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 474
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) click to toggle source

Renames a column.

Example
rename_column(:suppliers, :description, :name)
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 227
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) click to toggle source

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'
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 322
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) click to toggle source

Renames a table.

Example
rename_table('octopuses', 'octopi')
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 176
def rename_table(table_name, new_name)
  raise NotImplementedError, "rename_table is not implemented"
end
structure_dump() click to toggle source

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

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 356
def structure_dump
end
table_alias_for(table_name) click to toggle source

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

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 12
def table_alias_for(table_name)
  table_name[0..table_alias_length-1].gsub(/\./, '_')
end
table_exists?(table_name) click to toggle source

def tables(name = nil) end

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 18
def table_exists?(table_name)
  tables.include?(table_name.to_s)
end

Protected Instance Methods

options_include_default?(options) click to toggle source
# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 485
def options_include_default?(options)
  options.include?(:default) && !(options[:null] == false && options[:default].nil?)
end
quoted_columns_for_index(column_names, options = {}) click to toggle source

Overridden by the mysql adapter for supporting index lengths

# File lib/active_record/connection_adapters/abstract/schema_statements.rb, line 481
def quoted_columns_for_index(column_names, options = {})
  column_names.map {|name| quote_column_name(name) }
end

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