Class | Sequel::Schema::Generator |
In: |
lib/sequel/database/schema_generator.rb
lib/sequel/extensions/schema_dumper.rb |
Parent: | Object |
Schema::Generator is an internal class that the user is not expected to instantiate directly. Instances are created by Database#create_table. It is used to specify table creation parameters. It takes a Database object and a block of column/index/constraint specifications, and gives the Database a table description, which the database uses to create a table.
Schema::Generator has some methods but also includes method_missing, allowing users to specify column type as a method instead of using the column method, which makes for a nicer DSL.
For more information on Sequel‘s support for schema modification, see the "Migrations and Schema Modification" guide.
GENERIC_TYPES | = | [String, Integer, Fixnum, Bignum, Float, Numeric, BigDecimal, Date, DateTime, Time, File, TrueClass, FalseClass] | Classes specifying generic types that Sequel will convert to database-specific types. |
columns | [R] | Return the column hashes created by this generator |
constraints | [R] | Return the constraint hashes created by this generator |
indexes | [R] | Return the index hashes created by this generator |
Add a method for each of the given types that creates a column with that type as a constant. Types given should either already be constants/classes or a capitalized string/symbol with the same name as a constant/class.
# File lib/sequel/database/schema_generator.rb, line 47 47: def self.add_type_method(*types) 48: types.each do |type| 49: class_eval("def #{type}(name, opts={}); column(name, #{type}, opts); end", __FILE__, __LINE__) 50: end 51: end
Set the database in which to create the table, and evaluate the block in the context of this object.
# File lib/sequel/database/schema_generator.rb, line 33 33: def initialize(db, &block) 34: @db = db 35: @columns = [] 36: @indexes = [] 37: @constraints = [] 38: @primary_key = nil 39: instance_eval(&block) if block 40: @columns.unshift(@primary_key) if @primary_key && !has_column?(primary_key_name) 41: end
Add an unnamed constraint to the DDL, specified by the given block or args:
check(:num=>1..5) # CHECK num >= 1 AND num <= 5 check{num > 5} # CHECK num > 5
# File lib/sequel/database/schema_generator.rb, line 58 58: def check(*args, &block) 59: constraint(nil, *args, &block) 60: end
Add a column with the given name, type, and opts to the DDL.
column :num, :integer # num INTEGER column :name, String, :null=>false, :default=>'a' # name varchar(255) NOT NULL DEFAULT 'a' inet :ip # ip inet
You can also create columns via method missing, so the following are equivalent:
column :number, :integer integer :number
The following options are supported:
:default : | The default value for the column. |
:deferrable : | This ensure Referential Integrity will work even if reference table will use for its foreign key a value that does not exists(yet) on referenced table. Basically it adds DEFERRABLE INITIALLY DEFERRED on key creation. |
:index : | Create an index on this column. |
:key : | For foreign key columns, the column in the associated table that this column references. Unnecessary if this column references the primary key of the associated table. |
:null : | Mark the column as allowing NULL values (if true), or not allowing NULL values (if false). If unspecified, will default to whatever the database default is. |
:on_delete : | Specify the behavior of this column when being deleted (:restrict, cascade, :set_null, :set_default, :no_action). |
:on_update : | Specify the behavior of this column when being updated (:restrict, cascade, :set_null, :set_default, :no_action). |
:primary_key : | Make the column as a single primary key column. This should only be used if you have a single, nonautoincrementing primary key column. |
:size : | The size of the column, generally used with string columns to specify the maximum number of characters the column will hold. An array of two integers can be provided to set the size and the precision, respectively, of decimal columns. |
:unique : | Mark the column as unique, generally has the same effect as creating a unique index on the column. |
:unsigned : | Make the column type unsigned, only useful for integer columns. |
# File lib/sequel/database/schema_generator.rb, line 107 107: def column(name, type, opts = {}) 108: columns << {:name => name, :type => type}.merge(opts) 109: index(name) if opts[:index] 110: end
Adds a named constraint (or unnamed if name is nil) to the DDL, with the given block or args.
constraint(:blah, :num=>1..5) # CONSTRAINT blah CHECK num >= 1 AND num <= 5 check(:foo){num > 5} # CONSTRAINT foo CHECK num > 5
# File lib/sequel/database/schema_generator.rb, line 117 117: def constraint(name, *args, &block) 118: constraints << {:name => name, :type => :check, :check => block || args} 119: end
Dump this generator‘s columns to a string that could be evaled inside another instance to represent the same columns
# File lib/sequel/extensions/schema_dumper.rb, line 192 192: def dump_columns 193: strings = [] 194: cols = columns.dup 195: if pkn = primary_key_name 196: cols.delete_if{|x| x[:name] == pkn} 197: pk = @primary_key.dup 198: pkname = pk.delete(:name) 199: @db.serial_primary_key_options.each{|k,v| pk.delete(k) if v == pk[k]} 200: strings << "primary_key #{pkname.inspect}#{opts_inspect(pk)}" 201: end 202: cols.each do |c| 203: c = c.dup 204: name = c.delete(:name) 205: type = c.delete(:type) 206: opts = opts_inspect(c) 207: strings << if type.is_a?(Class) 208: "#{type.name} #{name.inspect}#{opts}" 209: else 210: "column #{name.inspect}, #{type.inspect}#{opts}" 211: end 212: end 213: strings.join("\n") 214: end
Dump this generator‘s constraints to a string that could be evaled inside another instance to represent the same constraints
# File lib/sequel/extensions/schema_dumper.rb, line 218 218: def dump_constraints 219: cs = constraints.map do |c| 220: c = c.dup 221: type = c.delete(:type) 222: case type 223: when :check 224: raise(Error, "can't dump check/constraint specified with Proc") if c[:check].is_a?(Proc) 225: name = c.delete(:name) 226: if !name and c[:check].length == 1 and c[:check].first.is_a?(Hash) 227: "check #{c[:check].first.inspect[1...-1]}" 228: else 229: "#{name ? "constraint #{name.inspect}," : 'check'} #{c[:check].map{|x| x.inspect}.join(', ')}" 230: end 231: else 232: cols = c.delete(:columns) 233: "#{type} #{cols.inspect}#{opts_inspect(c)}" 234: end 235: end 236: cs.join("\n") 237: end
Dump this generator‘s indexes to a string that could be evaled inside another instance to represent the same indexes. Options:
# File lib/sequel/extensions/schema_dumper.rb, line 246 246: def dump_indexes(options={}) 247: is = indexes.map do |c| 248: c = c.dup 249: cols = c.delete(:columns) 250: if table = options[:add_index] || options[:drop_index] 251: "#{options[:drop_index] ? 'drop' : 'add'}_index #{table.inspect}, #{cols.inspect}#{', :ignore_errors=>true' if options[:ignore_errors]}#{opts_inspect(c)}" 252: else 253: "index #{cols.inspect}#{opts_inspect(c)}" 254: end 255: end 256: is.join("\n") 257: end
Add a foreign key in the table that references another table to the DDL. See column for available options.
foreign_key(:artist_id) # artist_id INTEGER foreign_key(:artist_id, :artists) # artist_id INTEGER REFERENCES artists foreign_key(:artist_id, :artists, :key=>:id) # artist_id INTEGER REFERENCES artists(id)
# File lib/sequel/database/schema_generator.rb, line 127 127: def foreign_key(name, table=nil, opts = {}) 128: opts = case table 129: when Hash 130: table.merge(opts) 131: when Symbol 132: opts.merge(:table=>table) 133: when NilClass 134: opts 135: else 136: raise(Error, "The second argument to foreign_key should be a Hash, Symbol, or nil") 137: end 138: return composite_foreign_key(name, opts) if name.is_a?(Array) 139: column(name, Integer, opts) 140: end
Add an index on the given column(s) with the given options to the DDL. The available options are:
:type : | The type of index to use (only supported by some databases) |
:unique : | Make the index unique, so duplicate values are not allowed. |
:where : | Create a partial index (only supported by some databases) |
index :name # CREATE INDEX table_name_index ON table (name) index [:artist_id, :name] # CREATE INDEX table_artist_id_name_index ON table (artist_id, name)
# File lib/sequel/database/schema_generator.rb, line 164 164: def index(columns, opts = {}) 165: indexes << {:columns => Array(columns)}.merge(opts) 166: end
Adds an autoincrementing primary key column or a primary key constraint to the DDL. To create a constraint, the first argument should be an array of column symbols specifying the primary key columns. To create an autoincrementing primary key column, a single symbol can be used. In both cases, an options hash can be used as the second argument.
If you want to create a primary key column that is not autoincrementing, you should not use this method. Instead, you should use the regular column method with a :primary_key=>true option.
Examples:
primary_key(:id) primary_key([:street_number, :house_number])
# File lib/sequel/database/schema_generator.rb, line 187 187: def primary_key(name, *args) 188: return composite_primary_key(name, *args) if name.is_a?(Array) 189: @primary_key = @db.serial_primary_key_options.merge({:name => name}) 190: 191: if opts = args.pop 192: opts = {:type => opts} unless opts.is_a?(Hash) 193: if type = args.pop 194: opts.merge!(:type => type) 195: end 196: @primary_key.merge!(opts) 197: end 198: @primary_key 199: end
The name of the primary key for this generator, if it has a primary key.
# File lib/sequel/database/schema_generator.rb, line 202 202: def primary_key_name 203: @primary_key[:name] if @primary_key 204: end
Add a unique constraint on the given columns to the DDL.
unique(:name) # UNIQUE (name)
# File lib/sequel/database/schema_generator.rb, line 214 214: def unique(columns, opts = {}) 215: constraints << {:type => :unique, :columns => Array(columns)}.merge(opts) 216: end