Class: ActiveRecord::ConnectionAdapters::TableDefinition

Inherits:

Object

• Object
• ActiveRecord::ConnectionAdapters::TableDefinition

Defined in:

lib/active_record/connection_adapters/abstract/schema_definitions.rb

Overview

Represents a SQL table in an abstract way. Columns are stored as ColumnDefinition in the #columns attribute.

Instance Attribute Summary

• #columns ⇒ Object

  Returns the value of attribute columns.

Instance Method Summary

• #[](name) ⇒ Object

  Returns a ColumnDefinition for the column with name name.

• #column(name, type, options = {}) ⇒ Object

  Instantiates a new column for the table.

• #initialize(base) ⇒ TableDefinition constructor

  A new instance of TableDefinition.

• #primary_key(name) ⇒ Object

  Appends a primary key definition to the table definition.

• #to_sql ⇒ Object

  Returns a String whose contents are the column definitions concatenated together.

Constructor Details

#initialize(base) ⇒ TableDefinition

Returns a new instance of TableDefinition.

# File 'lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 230

def initialize(base)
  @columns = []
  @base = base
end

Instance Attribute Details

#columns ⇒ Object

Returns the value of attribute columns.

# File 'lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 228

def columns
  @columns
end

Instance Method Details

#[](name) ⇒ Object

Returns a ColumnDefinition for the column with name name.

# File 'lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 242

def [](name)
  @columns.find {|column| column.name.to_s == name.to_s}
end

#column(name, type, options = {}) ⇒ Object

Instantiates a new column for the table. The type parameter must be one of the following values: :primary_key, :string, :text, :integer, :float, :decimal, :datetime, :timestamp, :time, :date, :binary, :boolean.

Available options are (none of these exists by default):

• :limit: Requests a maximum column length (:string, :text, :binary or :integer columns only)
• :default: The column's default value. Use nil for NULL.
• :null: Allows or disallows NULL values in the column. This option could have been named :null_allowed.
• :precision: Specifies the precision for a :decimal column.
• :scale: Specifies the scale for a :decimal column.

Please be aware of different RDBMS implementations behavior with :decimal columns:

• The SQL standard says the default scale should be 0, :scale <= :precision, and makes no comments about the requirements of :precision.
• MySQL: :precision [1..63], :scale [0..30]. Default is (10,0).
• PostgreSQL: :precision [1..infinity], :scale [0..infinity]. No default.
• SQLite2: Any :precision and :scale may be used. Internal storage as strings. No default.
• SQLite3: No restrictions on :precision and :scale, but the maximum supported :precision is 16. No default.
• Oracle: :precision [1..38], :scale [-84..127]. Default is (38,0).
• DB2: :precision [1..63], :scale [0..62]. Default unknown.
• Firebird: :precision [1..18], :scale [0..18]. Default (9,0). Internal types NUMERIC and DECIMAL have different storage rules, decimal being better.
• FrontBase?: :precision [1..38], :scale [0..38]. Default (38,0). WARNING Max :precision/:scale for NUMERIC is 19, and DECIMAL is 38.
• SqlServer?: :precision [1..38], :scale [0..38]. Default (38,0).
• Sybase: :precision [1..38], :scale [0..38]. Default (38,0).
• OpenBase?: Documentation unclear. Claims storage in double.

This method returns self.

Examples

Assuming td is an instance of TableDefinition

td.column(:granted, :boolean) #=> granted BOOLEAN

td.column(:picture, :binary, :limit => 2.megabytes) #=> picture BLOB(2097152)

td.column(:sales_stage, :string, :limit => 20, :default => 'new', :null => false) #=> sales_stage VARCHAR(20) DEFAULT 'new' NOT NULL

def.column(:bill_gates_money, :decimal, :precision => 15, :scale => 2) #=> bill_gates_money DECIMAL(15,2)

def.column(:sensor_reading, :decimal, :precision => 30, :scale => 20) #=> sensor_reading DECIMAL(30,20)

While :scale defaults to zero on most databases, it

probably wouldn't hurt to include it.

def.column(:huge_integer, :decimal, :precision => 30) #=> huge_integer DECIMAL(30)

# File 'lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 319

def column(name, type, options = {})
  column = self[name] || ColumnDefinition.new(@base, name, type)
  column.limit = options[:limit] || native[type.to_sym][:limit] if options[:limit] or native[type.to_sym]
  column.precision = options[:precision]
  column.scale = options[:scale]
  column.default = options[:default]
  column.null = options[:null]
  @columns << column unless @columns.include? column
  self
end

#primary_key(name) ⇒ Object

Appends a primary key definition to the table definition. Can be called multiple times, but this is probably not a good idea.

# File 'lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 237

def primary_key(name)
  column(name, :primary_key)
end

#to_sql ⇒ Object

Returns a String whose contents are the column definitions concatenated together. This string can then be pre and appended to to generate the final SQL to create the table.

# File 'lib/active_record/connection_adapters/abstract/schema_definitions.rb', line 333

def to_sql
  @columns * ', '
end