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 143

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

Instance Attribute Details

#columns ⇒ Object (readonly)

Return the columns 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 constraints 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 indexes 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 a unnamed constraint to the DDL, specified by the given block or args.



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# File 'lib/sequel/database/schema_generator.rb', line 55

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.

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.

  • :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. See Schema::SQL#on_delete_clause for options.

  • :on_update - Specify the behavior of this column when being updated. See Schema::SQL#on_delete_clause for options.

  • :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.

  • :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.



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# File 'lib/sequel/database/schema_generator.rb', line 93

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.



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# File 'lib/sequel/database/schema_generator.rb', line 100

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.



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# File 'lib/sequel/database/schema_generator.rb', line 106

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 122

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 127

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)



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# File 'lib/sequel/database/schema_generator.rb', line 137

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

#primary_key(name, *args) ⇒ Object

Add primary key information to the DDL. Takes between one and three arguments. The last one is an options hash as for Generator#column. The first one distinguishes two modes: an array of existing column names adds a composite primary key constraint. A single symbol adds a new column of that name and makes it the primary key. In that case the optional middle argument denotes the type.

Examples:

primary_key(:id)
primary_key(:zip_code, :null => false)
primary_key([:street_number, :house_number])
primary_key(:id, :string, :auto_increment => false)



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# File 'lib/sequel/database/schema_generator.rb', line 159

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 table, if it has a primary key.



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# File 'lib/sequel/database/schema_generator.rb', line 174

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 179

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.



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# File 'lib/sequel/database/schema_generator.rb', line 184

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