Class: Sequel::Schema::Generator

Inherits:
Object
  • Object
show all
Defined in:
lib/sequel_core/schema/generator.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.

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_core/schema/generator.rb', line 18

def initialize(db, &block)
  @db = db
  @columns = []
  @indexes = []
  @primary_key = nil
  instance_eval(&block) if block
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_core/schema/generator.rb', line 118

def method_missing(type, name = nil, opts = {})
  name ? column(name, type, opts) : super
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_core/schema/generator.rb', line 28

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.

  • :unique - Mark the column is 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_core/schema/generator.rb', line 60

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_core/schema/generator.rb', line 67

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

#create_info ⇒ Object

Return the DDL created by the generator as a array of two elements, the first being the columns and the second being the indexes.



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# File 'lib/sequel_core/schema/generator.rb', line 74

def create_info
  @columns.unshift(@primary_key) if @primary_key && !has_column?(primary_key_name)
  [@columns, @indexes]
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_core/schema/generator.rb', line 81

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 seconds 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_core/schema/generator.rb', line 97

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_core/schema/generator.rb', line 102

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_core/schema/generator.rb', line 112

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_core/schema/generator.rb', line 134

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_core/schema/generator.rb', line 149

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_core/schema/generator.rb', line 154

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_core/schema/generator.rb', line 159

def unique(columns, opts = {})
  @columns << {:type => :check, :constraint_type => :unique,
               :name => nil, :columns => Array(columns)}.merge(opts)
end