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 192

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 390

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)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 261

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
  quoted_column_names = column_names.map { |e| quote_column_name(e) }.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 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 408

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 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 415

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) ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 339

def assume_migrated_upto_version(version)
  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['db/migrate/[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 214

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 224

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 174

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 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 32

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 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 100

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

  yield table_definition

  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 402

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 186

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 308

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_name(table_name, options) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 289

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_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 316

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 => 'unique_schema_migrations'

    # 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 ⇒ 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 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 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 202

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

def remove_index(table_name, options = {})
  execute "DROP INDEX #{quote_column_name(index_name(table_name, options))} 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 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 423

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 231

def rename_column(table_name, column_name, new_column_name)
  raise NotImplementedError, "rename_column is not implemented"
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 181

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 305

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 17

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

#table_alias_length ⇒ Object

This is the maximum length a table alias can be



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 12

def table_alias_length
  255
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 23

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 363

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