Class: Sequel::Schema::AlterTableOperations

Inherits:
Object
  • Object
show all
Defined in:
lib/sequel/schema/alter_table_operations.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ AlterTableOperations

Returns a new instance of AlterTableOperations.



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# File 'lib/sequel/schema/alter_table_operations.rb', line 4

def initialize(options={})
  @immutable_columns = options[:immutable_columns]
end

Class Method Details

.build(db_table, new_table, options = {}) ⇒ Object

Returns an array of operations to change the current database table to be like the defined table.



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# File 'lib/sequel/schema/alter_table_operations.rb', line 11

def self.build(db_table, new_table, options={})
  new(options).build(db_table, new_table)
end

Instance Method Details

#build(db_table, new_table) ⇒ Object 



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# File 'lib/sequel/schema/alter_table_operations.rb', line 15

def build(db_table, new_table)
  db_columns = db_table[:columns].inject({}) {|hsh, column| hsh[column.name] = column; hsh }
  new_column_names = new_table[:columns].map {|c| c.name }
  dropped_columns = db_columns.keys - new_column_names

  operations = new_table[:columns].map do |column|
    if db_columns[column.name]
      build_column_operations db_columns[column.name], column
    else
      column.add_statement
    end
  end.flatten

  operations += dropped_columns.map do |name| 
    db_columns[name].drop_statement
  end

  db_indexes = Schema::DbIndex.build_from_hash(db_table[:indexes] || {})
  new_indexes = Schema::DbIndex.build_from_hash(new_table[:indexes] || {})
  
  operations += (db_indexes - new_indexes).map do |index|
    index.drop_statement unless index.columns.all? {|c| dropped_columns.include?(c) }
  end
  
  operations += (new_indexes - db_indexes).map do |index|
    index.add_statement          
  end
  
  operations        
end

#build_column_operations(db_column, new_column) ⇒ Object

Returns an array of operations to change the current database column to be like the defined column.



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# File 'lib/sequel/schema/alter_table_operations.rb', line 49

def build_column_operations(db_column, new_column)
  result = []
  
  diffs = db_column.diff(new_column)

  if @immutable_columns && !diffs.empty?
    result << :drop_statement
    result << :add_statement
  else
    result << :change_type_statement    if [:elements, :column_type, :size, :unsigned].any? {|sym| diffs.include?(sym) }
    # only need to explicitly set the default if we're not changing the column type.
    result << :change_default_statement if diffs.include?(:default) && result.empty?
    result << :change_null_statement    if diffs.include?(:null)
  end
  
  result.map {|statement| new_column.__send__(statement) }
end