class Sequel::Schema::CreateTableGenerator

  1. lib/sequel/database/schema_generator.rb
Superclass: Object

Schema::CreateTableGenerator 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::CreateTableGenerator 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 “Schema Modification” guide.


GENERIC_TYPES = %w'String Integer Float Numeric BigDecimal Date DateTime Time File TrueClass FalseClass'.freeze  

Classes specifying generic types that Sequel will convert to database-specific types.


columns [R]

Column hashes created by this generator

constraints [R]

Constraint hashes created by this generator

indexes [R]

Index hashes created by this generator

Public Class methods


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.

[show source]
   # File lib/sequel/database/schema_generator.rb
59 def self.add_type_method(*types)
60   types.each do |type|
61     case type
62     when Symbol, String
63       method = type
64       type = Object.const_get(type)
65     else
66       method = type.to_s
67     end
69     define_method(method){|name, opts=OPTS| column(name, type, opts)}
70   end
71   nil
72 end
new(db, &block)

Set the database in which to create the table, and evaluate the block in the context of this object.

[show source]
   # File lib/sequel/database/schema_generator.rb
34 def initialize(db, &block)
35   @db = db
36   @columns = []
37   @indexes = []
38   @constraints = []
39   @primary_key = nil
40   instance_exec(&block) if block
41 end

Public Instance methods

Bignum(name, opts=OPTS)

Use custom Bignum method to use :Bignum instead of Bignum class, to work correctly in cases where Bignum is the same as Integer.

[show source]
   # File lib/sequel/database/schema_generator.rb
45 def Bignum(name, opts=OPTS)
46   column(name, :Bignum, opts)
47 end
Fixnum(name, opts=OPTS)

Use custom Fixnum method to use Integer instead of Fixnum class, to avoid warnings on ruby 2.4+.

[show source]
   # File lib/sequel/database/schema_generator.rb
51 def Fixnum(name, opts=OPTS)
52   column(name, Integer, opts)
53 end
check(*args, &block)

Add an unnamed constraint, specified by the given block or args:

check(num: 1..5) # CHECK num >= 1 AND num <= 5
check{num > 5}   # CHECK num > 5
[show source]
   # File lib/sequel/database/schema_generator.rb
79 def check(*args, &block)
80   constraint(nil, *args, &block)
81 end
column(name, type, opts = OPTS)

Add a column with the given name, type, and opts:

column :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:


The collation to use for the column. For backwards compatibility, only symbols and string values are supported, and they are used verbatim. However, on PostgreSQL, symbols are literalized as regular identifiers, since unquoted collations are unlikely to be valid.


The default value for the column.


For foreign key columns, this ensures referential integrity will work even if referencing table uses a foreign key value that does not yet exist on referenced table (but will exist before the transaction commits). Basically it adds DEFERRABLE INITIALLY DEFERRED on key creation. If you use :immediate as the value, uses DEFERRABLE INITIALLY IMMEDIATE.


Specify a GENERATED ALWAYS AS column expression, if generated columns are supported (PostgreSQL 12+, MariaDB 5.2.0+, and MySQL 5.7.6+).


Create an index on this column. If given a hash, use the hash as the options for the index.


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, except if you are using MySQL.


Mark the column as allowing NULL values (if true), or not allowing NULL values (if false). The default is to allow NULL values.


Specify the behavior of this column when being deleted (:restrict, :cascade, :set_null, :set_default, :no_action).


Specify the behavior of this column when being updated (:restrict, :cascade, :set_null, :set_default, :no_action).


Make the column as a single primary key column. This should not be used if you want a single autoincrementing primary key column (use the primary_key method in that case).


The name to give the primary key constraint


Similar to :deferrable, but for the primary key constraint if :primary_key is used.


Overrides the type given as the argument. Generally not used by column itself, but can be passed as an option to other methods that call column.


Mark the column as unique, generally has the same effect as creating a unique index on the column.


The name to give the unique key constraint


Similar to :deferrable, but for the unique constraint if :unique is used.

PostgreSQL specific options:


Create an identity column.

MySQL specific options:


Set the type of column when using :generated_always_as, should be :virtual or :stored to force a type.


Use ON UPDATE CURRENT TIMESTAMP when defining the column, which will update the column value to CURRENT_TIMESTAMP on every UPDATE.

Microsoft SQL Server specific options:


When using :primary_key or :unique, marks the primary key or unique constraint as CLUSTERED (if true), or NONCLUSTERED (if false).

[show source]
    # File lib/sequel/database/schema_generator.rb
157 def column(name, type, opts = OPTS)
158   columns << {:name => name, :type => type}.merge!(opts)
159   if index_opts = opts[:index]
160     index(name, index_opts.is_a?(Hash) ? index_opts : OPTS)
161   end
162   nil
163 end
constraint(name, *args, &block)

Adds a named CHECK constraint (or unnamed if name is nil), with the given block or args. To provide options for the constraint, pass a hash as the first argument.

constraint(:blah, num: 1..5)
# CONSTRAINT blah CHECK num >= 1 AND num <= 5
constraint({name: :blah, deferrable: true}, num: 1..5)

If the first argument is a hash, the following options are supported:



The name of the CHECK constraint


Whether the CHECK constraint should be marked DEFERRABLE.

PostgreSQL specific options:


Whether the CHECK constraint should be marked NOT VALID.

[show source]
    # File lib/sequel/database/schema_generator.rb
182 def constraint(name, *args, &block)
183   opts = name.is_a?(Hash) ? name : {:name=>name}
184   constraints << opts.merge(:type=>:check, :check=>block || args)
185   nil
186 end
foreign_key(name, table=nil, opts = OPTS)

Add a foreign key in the table that references another table. 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)
foreign_key(:artist_id, :artists, type: String) # artist_id varchar(255) REFERENCES artists(id)

Additional Options:


The name to give the foreign key constraint

If you want a foreign key constraint without adding a column (usually because it is a composite foreign key), you can provide an array of columns as the first argument, and you can provide the :name option to name the constraint:

foreign_key([:artist_name, :artist_location], :artists, name: :artist_fk)
# ADD CONSTRAINT artist_fk FOREIGN KEY (artist_name, artist_location) REFERENCES artists
[show source]
    # File lib/sequel/database/schema_generator.rb
206 def foreign_key(name, table=nil, opts = OPTS)
207   opts = case table
208   when Hash
209     table.merge(opts)
210   when NilClass
211     opts
212   else
213     opts.merge(:table=>table)
214   end
215   return composite_foreign_key(name, opts) if name.is_a?(Array)
216   column(name, Integer, opts)
217 end
full_text_index(columns, opts = OPTS)

Add a full text index on the given columns. See index for additional options.

PostgreSQL specific options:


Can be set to :gist to use a GIST index instead of the default GIN index.


Set a language to use for the index (default: simple).

[show source]
    # File lib/sequel/database/schema_generator.rb
226 def full_text_index(columns, opts = OPTS)
227   index(columns, opts.merge(:type => :full_text))
228 end

True if the generator includes the creation of a column with the given name.

[show source]
    # File lib/sequel/database/schema_generator.rb
231 def has_column?(name)
232   columns.any?{|c| c[:name] == name}
233 end
index(columns, opts = OPTS)

Add an index on the given column(s) with the given options. Examples:

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)

index [:artist_id, :name], name: :foo
# CREATE INDEX foo ON table (artist_id, name)

General options:


Include additional column values in the index, without actually indexing on those values (only supported by some databases).


The name to use for the index. If not given, a default name based on the table and columns is used.


The type of index to use (only supported by some databases, :full_text and :spatial values are handled specially).


Make the index unique, so duplicate values are not allowed.


A filter expression, used to create a partial index (only supported by some databases).

PostgreSQL specific options:


Create the index concurrently, so it doesn’t block operations on the table while the index is being built.


Only create the index if an index of the same name doesn’t already exist.


Set whether separate NULLs should be considered distinct values in unique indexes.


Set an opclass to use for all columns (per-column opclasses require custom SQL).


Specify tablespace for index.

Microsoft SQL Server specific options:


Sets the KEY INDEX to the given value.

[show source]
    # File lib/sequel/database/schema_generator.rb
273 def index(columns, opts = OPTS)
274   indexes << {:columns => Array(columns)}.merge!(opts)
275   nil
276 end
method_missing(type, name = nil, opts = OPTS)

Add a column with the given type, name, and opts. See column for available options.

[show source]
    # File lib/sequel/database/schema_generator.rb
280 def method_missing(type, name = nil, opts = OPTS)
281   name ? column(name, type, opts) : super
282 end
primary_key(name, *args)

Adds an autoincrementing primary key column or a primary key constraint. To just 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.

If an array of column symbols is used, you can specify the :name option to name the constraint.



For non-composite primary keys, respects the existing order of columns, overriding the default behavior of making the primary key the first column.


primary_key(:id, type: :Bignum, keep_order: true)
primary_key([:street_number, :house_number], name: :some_constraint_name)
[show source]
    # File lib/sequel/database/schema_generator.rb
311 def primary_key(name, *args)
312   return composite_primary_key(name, *args) if name.is_a?(Array)
313   column = @db.serial_primary_key_options.merge({:name => name})
315   if opts = args.pop
316     opts = {:type => opts} unless opts.is_a?(Hash)
317     if type = args.pop
318       opts = opts.merge(:type => type)
319     end
320     column.merge!(opts)
321   end
323   @primary_key = column
324   if column[:keep_order]
325     columns << column
326   else
327     columns.unshift(column)
328   end
329   nil
330 end

The name of the primary key for this generator, if it has a primary key.

[show source]
    # File lib/sequel/database/schema_generator.rb
333 def primary_key_name
334   @primary_key[:name] if @primary_key
335 end
respond_to_missing?(meth, include_private)

This object responds to all methods.

[show source]
    # File lib/sequel/database/schema_generator.rb
285 def respond_to_missing?(meth, include_private)
286   true
287 end
spatial_index(columns, opts = OPTS)

Add a spatial index on the given columns. See index for additional options.

[show source]
    # File lib/sequel/database/schema_generator.rb
339 def spatial_index(columns, opts = OPTS)
340   index(columns, opts.merge(:type => :spatial))
341 end
unique(columns, opts = OPTS)

Add a unique constraint on the given columns.

unique(:name) # UNIQUE (name)

Supports the same :deferrable option as column. The :name option can be used to name the constraint.

[show source]
    # File lib/sequel/database/schema_generator.rb
349 def unique(columns, opts = OPTS)
350   constraints << {:type => :unique, :columns => Array(columns)}.merge!(opts)
351   nil
352 end