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 121

def add_column(table_name, column_name, type, options = {})
  add_column_sql = "ALTER TABLE #{table_name} ADD #{column_name} #{type_to_sql(type, options[:limit])}"
  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 264

def add_column_options!(sql, options) #:nodoc:
  sql << " DEFAULT #{quote(options[:default], options[:column])}" unless options[:default].nil?
  sql << " NOT NULL" if options[:null] == false
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 names, 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 colum :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_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 186

def add_index(table_name, column_name, options = {})
  index_name = "#{table_name}_#{Array(column_name).first}_index"

  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

  execute "CREATE #{index_type} INDEX #{index_name} ON #{table_name} (#{Array(column_name).join(", ")})"
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 139

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 apppropriate 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 149

def change_column_default(table_name, column_name, default)
  raise NotImplementedError, "change_column_default is not implemented"
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 28

def columns(table_name, name = nil) end

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

Creates a new table 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() yields a TableDefinition instance
create_table(:suppliers) do |t|
  t.column :name, :string, :limit => 60
  # Other fields here
end

Regular form

create_table(:suppliers)
add_column(:suppliers, :name, :string, {:limit => 60})

The options hash can include the following keys:

:id

Set to true or false to add/not add a primary key column automatically. Defaults to true.

: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 or false 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_join (
  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 90

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

  yield table_definition

  if options[:force]
    drop_table(name) rescue nil
  end

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

#drop_table(name) ⇒ Object

Drops a table from the database.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 115

def drop_table(name)
  execute "DROP TABLE #{name}"
end

#dump_schema_information ⇒ Object

:nodoc:



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

def dump_schema_information #:nodoc:
  begin
    if (current_schema = ActiveRecord::Migrator.current_version) > 0
      return "INSERT INTO #{ActiveRecord::Migrator.schema_info_table_name} (version) VALUES (#{current_schema})" 
    end
  rescue ActiveRecord::StatementInvalid 
    # No Schema Info
  end
end

#index_name(table_name, options) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 215

def index_name(table_name, options) #:nodoc:
  if Hash === options # legacy support
    if options[:column]
      "#{table_name}_#{options[:column]}_index"
    elsif options[:name]
      options[:name]
    else
      raise ArgumentError, "You must specify the index name"
    end
  else
    "#{table_name}_#{options}_index"
  end
end

#initialize_schema_information ⇒ 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 236

def initialize_schema_information
  begin
    execute "CREATE TABLE #{ActiveRecord::Migrator.schema_info_table_name} (version #{type_to_sql(:integer)})"
    execute "INSERT INTO #{ActiveRecord::Migrator.schema_info_table_name} (version) VALUES(0)"
  rescue ActiveRecord::StatementInvalid
    # Schema has been intialized
  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_name) ⇒ Object

Removes the column from the table definition.

Examples
remove_column(:suppliers, :qualification)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 130

def remove_column(table_name, column_name)
  execute "ALTER TABLE #{table_name} DROP #{column_name}"
end

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

Remove the given index from the table.

Remove the suppliers_name_index in the suppliers table (legacy support, use the second or third forms).

remove_index :suppliers, :name

Remove the index named accounts_branch_id in the accounts table.

remove_index :accounts, :column => :branch_id

Remove the index named by_branch_party in the accounts table.

remove_index :accounts, :name => :by_branch_party

You can remove an index on multiple columns by specifying the first column.

add_index :accounts, [:username, :password]
remove_index :accounts, :username



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 211

def remove_index(table_name, options = {})
  execute "DROP INDEX #{index_name(table_name, options)} ON #{table_name}"
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 156

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

#rename_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 110

def rename_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 231

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

#type_to_sql(type, limit = nil) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 256

def type_to_sql(type, limit = nil) #:nodoc:
  native = native_database_types[type]
  limit ||= native[:limit]
  column_type_sql = native[:name]
  column_type_sql << "(#{limit})" if limit
  column_type_sql
end