Module: ActiveRecord::ConnectionAdapters::SchemaStatements

Included in:
AbstractAdapter
Defined in:
activerecord/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 'activerecord/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_column_options!(sql, options) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 439

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 => {:name => 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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 270

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] || index_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) ⇒ Object

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 457

def add_order_by_for_association_limiting!(sql, options)
  sql << " ORDER BY #{options[:order]}"
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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 464

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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 388

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 = {}) ⇒ 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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 209

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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 219

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 'activerecord/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) ⇒ 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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 27

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

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.

Yields:

  • (table_definition)


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# File 'activerecord/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) ⇒ 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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 451

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 'activerecord/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

#dump_schema_informationObject

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 357

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, index_name, default) ⇒ Boolean

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.



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 347

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

#index_name(table_name, options) ⇒ Object

:nodoc:



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

def index_name(table_name, options) #:nodoc:
  if Hash === options # legacy support
    if options[:column]
      "index_#{table_name}_on_#{Array(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

#initialize_schema_migrations_tableObject

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 365

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_typesObject

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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 7

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)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 197

def remove_column(table_name, *column_names)
  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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 304

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_index!(table_name, index_name) ⇒ Object

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 313

def remove_index!(table_name, index_name) #:nodoc:
  execute "DROP INDEX #{quote_column_name(index_name)} ON #{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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 472

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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 226

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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 321

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 'activerecord/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_dumpObject

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 354

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 'activerecord/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) ⇒ Boolean

def tables(name = nil) end



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 18

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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 412

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