Class: Sequel::Schema::Generator

Inherits:
Object
  • Object
show all
Defined in:
lib/sequel/database/schema_generator.rb,
lib/sequel/extensions/schema_dumper.rb

Overview

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.

Constant Summary collapse

GENERIC_TYPES =

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

[String, Integer, Fixnum, Bignum, Float, Numeric, BigDecimal,
Date, DateTime, Time, File, TrueClass, FalseClass]

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(db, &block) ⇒ Generator

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



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# File 'lib/sequel/database/schema_generator.rb', line 33

def initialize(db, &block)
  @db = db
  @columns = []
  @indexes = []
  @constraints = []
  @primary_key = nil
  instance_eval(&block) if block
  @columns.unshift(@primary_key) if @primary_key && !has_column?(primary_key_name)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(type, name = nil, opts = {}) ⇒ Object

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



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# File 'lib/sequel/database/schema_generator.rb', line 170

def method_missing(type, name = nil, opts = {})
  name ? column(name, type, opts) : super
end

Instance Attribute Details

#columns ⇒ Object (readonly)

Return the column hashes created by this generator



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# File 'lib/sequel/database/schema_generator.rb', line 23

def columns
  @columns
end

#constraints ⇒ Object (readonly)

Return the constraint hashes created by this generator



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# File 'lib/sequel/database/schema_generator.rb', line 26

def constraints
  @constraints
end

#indexes ⇒ Object (readonly)

Return the index hashes created by this generator



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# File 'lib/sequel/database/schema_generator.rb', line 29

def indexes
  @indexes
end

Class Method Details

.add_type_method(*types) ⇒ Object

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.



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# File 'lib/sequel/database/schema_generator.rb', line 47

def self.add_type_method(*types)
  types.each do |type|
    class_eval("def #{type}(name, opts={}); column(name, #{type}, opts); end", __FILE__, __LINE__)
  end
end

Instance Method Details

#check(*args, &block) ⇒ Object

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



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# File 'lib/sequel/database/schema_generator.rb', line 58

def check(*args, &block)
  constraint(nil, *args, &block)
end

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

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.



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# File 'lib/sequel/database/schema_generator.rb', line 107

def column(name, type, opts = {})
  columns << {:name => name, :type => type}.merge(opts)
  index(name) if opts[:index]
end

#constraint(name, *args, &block) ⇒ Object

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



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# File 'lib/sequel/database/schema_generator.rb', line 117

def constraint(name, *args, &block)
  constraints << {:name => name, :type => :check, :check => block || args}
end

#dump_columns ⇒ Object

Dump this generator’s columns to a string that could be evaled inside another instance to represent the same columns



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# File 'lib/sequel/extensions/schema_dumper.rb', line 190

def dump_columns
  strings = []
  cols = columns.dup
  if pkn = primary_key_name
    cols.delete_if{|x| x[:name] == pkn}
    pk = @primary_key.dup
    pkname = pk.delete(:name)
    @db.serial_primary_key_options.each{|k,v| pk.delete(k) if v == pk[k]}
    strings << "primary_key #{pkname.inspect}#{opts_inspect(pk)}"
  end
  cols.each do |c|
    c = c.dup
    name = c.delete(:name)
    type = c.delete(:type)
    opts = opts_inspect(c)
    strings << if type.is_a?(Class)
      "#{type.name} #{name.inspect}#{opts}"
    else
      "column #{name.inspect}, #{type.inspect}#{opts}"
    end
  end
  strings.join("\n")
end

#dump_constraints ⇒ Object

Dump this generator’s constraints to a string that could be evaled inside another instance to represent the same constraints



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# File 'lib/sequel/extensions/schema_dumper.rb', line 216

def dump_constraints
  cs = constraints.map do |c|
    c = c.dup
    type = c.delete(:type)
    case type
    when :check
      raise(Error, "can't dump check/constraint specified with Proc") if c[:check].is_a?(Proc)
      name = c.delete(:name)
      if !name and c[:check].length == 1 and c[:check].first.is_a?(Hash)
        "check #{c[:check].first.inspect[1...-1]}"
      else
        "#{name ? "constraint #{name.inspect}," : 'check'} #{c[:check].map{|x| x.inspect}.join(', ')}"
      end
    else
      cols = c.delete(:columns)
      "#{type} #{cols.inspect}#{opts_inspect(c)}"
    end
  end
  cs.join("\n")
end

#dump_indexes(options = {}) ⇒ Object

Dump this generator’s indexes to a string that could be evaled inside another instance to represent the same indexes. Options:

  • :add_index - Use add_index instead of index, so the methods can be called outside of a generator but inside a migration. The value of this option should be the table name to use.

  • :drop_index - Same as add_index, but create drop_index statements.

  • :ignore_errors - Add the ignore_errors option to the outputted indexes



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# File 'lib/sequel/extensions/schema_dumper.rb', line 244

def dump_indexes(options={})
  is = indexes.map do |c|
    c = c.dup
    cols = c.delete(:columns)
    if table = options[:add_index] || options[:drop_index]
      "#{options[:drop_index] ? 'drop' : 'add'}_index #{table.inspect}, #{cols.inspect}#{', :ignore_errors=>true' if options[:ignore_errors]}#{opts_inspect(c)}"
    else
      "index #{cols.inspect}#{opts_inspect(c)}"
    end
  end
  is.join("\n")
end

#foreign_key(name, table = nil, opts = {}) ⇒ Object

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)



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# File 'lib/sequel/database/schema_generator.rb', line 127

def foreign_key(name, table=nil, opts = {})
  opts = case table
  when Hash
    table.merge(opts)
  when Symbol
    opts.merge(:table=>table)
  when NilClass
    opts
  else
    raise(Error, "The second argument to foreign_key should be a Hash, Symbol, or nil")
  end
  return composite_foreign_key(name, opts) if name.is_a?(Array)
  column(name, Integer, opts)
end

#full_text_index(columns, opts = {}) ⇒ Object

Add a full text index on the given columns to the DDL.



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# File 'lib/sequel/database/schema_generator.rb', line 143

def full_text_index(columns, opts = {})
  index(columns, opts.merge(:type => :full_text))
end

#has_column?(name) ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/schema_generator.rb', line 148

def has_column?(name)
  columns.any?{|c| c[:name] == name}
end

#index(columns, opts = {}) ⇒ Object

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)



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# File 'lib/sequel/database/schema_generator.rb', line 164

def index(columns, opts = {})
  indexes << {:columns => Array(columns)}.merge(opts)
end

#primary_key(name, *args) ⇒ Object

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])



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# File 'lib/sequel/database/schema_generator.rb', line 187

def primary_key(name, *args)
  return composite_primary_key(name, *args) if name.is_a?(Array)
  @primary_key = @db.serial_primary_key_options.merge({:name => name})
  
  if opts = args.pop
    opts = {:type => opts} unless opts.is_a?(Hash)
    if type = args.pop
      opts.merge!(:type => type)
    end
    @primary_key.merge!(opts)
  end
  @primary_key
end

#primary_key_name ⇒ Object

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



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# File 'lib/sequel/database/schema_generator.rb', line 202

def primary_key_name
  @primary_key[:name] if @primary_key
end

#spatial_index(columns, opts = {}) ⇒ Object

Add a spatial index on the given columns to the DDL.



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# File 'lib/sequel/database/schema_generator.rb', line 207

def spatial_index(columns, opts = {})
  index(columns, opts.merge(:type => :spatial))
end

#unique(columns, opts = {}) ⇒ Object

Add a unique constraint on the given columns to the DDL.

unique(:name) # UNIQUE (name)



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# File 'lib/sequel/database/schema_generator.rb', line 214

def unique(columns, opts = {})
  constraints << {:type => :unique, :columns => Array(columns)}.merge(opts)
end