Class: HoboFields::MigrationGenerator

Inherits:
Object
  • Object
show all
Defined in:
lib/hobo_fields/migration_generator.rb

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ambiguity_resolver = {}) ⇒ MigrationGenerator

Returns a new instance of MigrationGenerator.



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# File 'lib/hobo_fields/migration_generator.rb', line 56

def initialize(ambiguity_resolver={})
  @ambiguity_resolver = ambiguity_resolver
  @drops = []
  @renames = nil
end

Class Attribute Details

.disable_indexing ⇒ Object

Returns the value of attribute disable_indexing.



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# File 'lib/hobo_fields/migration_generator.rb', line 47

def disable_indexing
  @disable_indexing
end

.ignore_models ⇒ Object

Returns the value of attribute ignore_models.



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# File 'lib/hobo_fields/migration_generator.rb', line 47

def ignore_models
  @ignore_models
end

.ignore_tables ⇒ Object

Returns the value of attribute ignore_tables.



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# File 'lib/hobo_fields/migration_generator.rb', line 47

def ignore_tables
  @ignore_tables
end

Instance Attribute Details

#renames ⇒ Object

Returns the value of attribute renames.



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# File 'lib/hobo_fields/migration_generator.rb', line 62

def renames
  @renames
end

Class Method Details

.connection ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 83

def self.connection
  ActiveRecord::Base.connection
end

.fix_native_types(types) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 89

def self.fix_native_types(types)
  case connection.class.name
  when /mysql/i
    types[:integer][:limit] ||= 11
  end
  types
end

.native_types ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 97

def self.native_types
  @native_types ||= fix_native_types connection.native_database_types
end

.run(renames = {}) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 50

def self.run(renames={})
  g = MigrationGenerator.new
  g.renames = renames
  g.generate
end

Instance Method Details

#always_ignore_tables ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 179

def always_ignore_tables
  # TODO: figure out how to do this in a sane way and be compatible with 2.2 and 2.3 - class has moved
  sessions_table = CGI::Session::ActiveRecordStore::Session.table_name if
    defined?(CGI::Session::ActiveRecordStore::Session) &&
    defined?(ActionController::Base) &&
    ActionController::Base.session_store == CGI::Session::ActiveRecordStore
  ['schema_info', 'schema_migrations',  sessions_table].compact
end

#change_column_back(table, column) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 416

def change_column_back(table, column)
  type, options = column_options_from_reverted_table(table, column)
  "change_column :#{table}, :#{column}, #{type}#{', ' + options.strip if options}"
end

#change_indexes(model, old_table_name) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 357

def change_indexes(model, old_table_name)
  return [[],[]] if MigrationGenerator.disable_indexing || model.is_a?(HabtmModelShim)
  new_table_name = model.table_name
  existing_indexes = IndexSpec.for_model(model, old_table_name)
  model_indexes = model.index_specs
  add_indexes = model_indexes - existing_indexes
  drop_indexes = existing_indexes - model_indexes
  undo_add_indexes = []
  undo_drop_indexes = []
  add_indexes.map! do |i|
    undo_add_indexes << drop_index(old_table_name, i.name)
    i.to_add_statement(new_table_name)
  end
  drop_indexes.map! do |i|
    undo_drop_indexes << i.to_add_statement(old_table_name)
    drop_index(new_table_name, i.name)
  end
  # the order is important here - adding a :unique, for instance needs to remove then add
  [drop_indexes + add_indexes, undo_add_indexes + undo_drop_indexes]
end

#change_table(model, current_table_name) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 279

def change_table(model, current_table_name)
  new_table_name = model.table_name

  db_columns = model.connection.columns(current_table_name).index_by{|c|c.name}
  key_missing = db_columns[model.primary_key].nil? && model.primary_key
  db_columns -= [model.primary_key]
  
  model_column_names = model.field_specs.keys.*.to_s
  db_column_names = db_columns.keys.*.to_s

  to_add = model_column_names - db_column_names
  to_add += [model.primary_key] if key_missing && model.primary_key
  to_remove = db_column_names - model_column_names
  to_remove = to_remove - [model.primary_key.to_sym] if model.primary_key

  to_rename = extract_column_renames!(to_add, to_remove, new_table_name)
  
  db_column_names -= to_rename.keys
  db_column_names |= to_rename.values
  to_change = db_column_names & model_column_names

  renames = to_rename.map do |old_name, new_name|
    "rename_column :#{new_table_name}, :#{old_name}, :#{new_name}"
  end
  undo_renames = to_rename.map do |old_name, new_name|
    "rename_column :#{new_table_name}, :#{new_name}, :#{old_name}"
  end

  to_add = to_add.sort_by {|c| model.field_specs[c].position }
  adds = to_add.map do |c|
    spec = model.field_specs[c]
    args = [":#{spec.sql_type}"] + format_options(spec.options, spec.sql_type)
    "add_column :#{new_table_name}, :#{c}, #{args * ', '}"
  end
  undo_adds = to_add.map do |c|
    "remove_column :#{new_table_name}, :#{c}"
  end

  removes = to_remove.map do |c|
    "remove_column :#{new_table_name}, :#{c}"
  end
  undo_removes = to_remove.map do |c|
    revert_column(current_table_name, c)
  end

  old_names = to_rename.invert
  changes = []
  undo_changes = []
  to_change.each do |c|
    col_name = old_names[c] || c
    col = db_columns[col_name]
    spec = model.field_specs[c]
    if spec.different_to?(col)
      change_spec = {}
      change_spec[:limit]     = spec.limit     unless spec.limit.nil? && col.limit.nil?
      change_spec[:precision] = spec.precision unless spec.precision.nil?
      change_spec[:scale]     = spec.scale     unless spec.scale.nil?
      change_spec[:null]      = spec.null      unless spec.null && col.null
      change_spec[:default]   = spec.default   unless spec.default.nil? && col.default.nil?
      change_spec[:comment]   = spec.comment   unless spec.comment.nil? && col.try.comment.nil?

      changes << "change_column :#{new_table_name}, :#{c}, " +
        ([":#{spec.sql_type}"] + format_options(change_spec, spec.sql_type, true)).join(", ")
      back = change_column_back(current_table_name, col_name)
      undo_changes << back unless back.blank?
    else
      nil
    end
  end.compact

  index_changes, undo_index_changes = change_indexes(model, current_table_name)

  [(renames + adds + removes + changes) * "\n",
   (undo_renames + undo_adds + undo_removes + undo_changes) * "\n",
   index_changes * "\n",
   undo_index_changes * "\n"]
end

#column_options_from_reverted_table(table, column) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 402

def column_options_from_reverted_table(table, column)
  revert = revert_table(table)
  if (md = revert.match(/\s*t\.column\s+"#{column}",\s+(:[a-zA-Z0-9_]+)(?:,\s+(.*?)$)?/m))
    # Ugly migration
    _, type, options = *md
  elsif (md = revert.match(/\s*t\.([a-z_]+)\s+"#{column}"(?:,\s+(.*?)$)?/m))
    # Sexy migration
    _, type, options = *md
    type = ":#{type}"
  end
  [type, options]
end

#connection ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 86

def connection; self.class.connection; end

#create_field(field_spec, field_name_width) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 274

def create_field(field_spec, field_name_width)
  args = [field_spec.name.inspect] + format_options(field_spec.options, field_spec.sql_type)
  "  t.%-*s %s" % [field_name_width, field_spec.sql_type, args.join(', ')]
end

#create_indexes(model) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 270

def create_indexes(model)
  model.index_specs.map { |i| i.to_add_statement(model.table_name) }
end

#create_table(model) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 256

def create_table(model)
  longest_field_name = model.field_specs.values.map { |f| f.sql_type.to_s.length }.max
  if model.primary_key != "id"
    if model.primary_key
      primary_key_option = ", :primary_key => :#{model.primary_key}"
    else
      primary_key_option = ", :id => false"
    end
  end
  (["create_table :#{model.table_name}#{primary_key_option} do |t|"] +
   model.field_specs.values.sort_by{|f| f.position}.map {|f| create_field(f, longest_field_name)} +
   ["end"] + (MigrationGenerator.disable_indexing ? [] : create_indexes(model))) * "\n"
end

#drop_index(table, name) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 378

def drop_index(table, name)
  # see https://hobo.lighthouseapp.com/projects/8324/tickets/566
  # for why the rescue exists
  "remove_index :#{table}, :name => :#{name} rescue ActiveRecord::StatementInvalid"
end

#extract_column_renames!(to_add, to_remove, table_name) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 153

def extract_column_renames!(to_add, to_remove, table_name)
  if renames
    to_rename = {}
    column_renames = renames._?[table_name.to_sym]
    if column_renames
      # A hash of table renames has been provided

      column_renames.each_pair do |old_name, new_name|
        if to_add.delete(new_name.to_s) && to_remove.delete(old_name.to_s)
          to_rename[old_name.to_s] = new_name.to_s
        else
          raise MigrationGeneratorError, "Invalid rename specified: #{old_name} => #{new_name}"
        end
      end
    end
    to_rename

  elsif @ambiguity_resolver
    @ambiguity_resolver.extract_renames!(to_add, to_remove, "column", "#{table_name}.")

  else
    raise MigrationGeneratorError, "Unable to resolve migration ambiguities in table #{table_name}"
  end
end

#extract_table_renames!(to_create, to_drop) ⇒ Object

return a hash of table renames and modifies the passed arrays so that renamed tables are no longer listed as to_create or to_drop



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# File 'lib/hobo_fields/migration_generator.rb', line 127

def extract_table_renames!(to_create, to_drop)
  if renames
    # A hash of table renames has been provided

    to_rename = {}
    renames.each_pair do |old_name, new_name|
      new_name = new_name[:table_name] if new_name.is_a?(Hash)
      next unless new_name

      if to_create.delete(new_name.to_s) && to_drop.delete(old_name.to_s)
        to_rename[old_name.to_s] = new_name.to_s
      else
        raise MigrationGeneratorError, "Invalid table rename specified: #{old_name} => #{new_name}"
      end
    end
    to_rename

  elsif @ambiguity_resolver
    @ambiguity_resolver.extract_renames!(to_create, to_drop, "table")

  else
    raise MigrationGeneratorError, "Unable to resolve migration ambiguities"
  end
end

#format_options(options, type, changing = false) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 384

def format_options(options, type, changing=false)
  options.map do |k, v|
    unless changing
      next if k == :limit && (type == :decimal || v == native_types[type][:limit])
      next if k == :null && v == true
    end
    "#{k.inspect} => #{v.inspect}"
  end.compact
end

#generate ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 189

def generate
  models, db_tables = models_and_tables
  models_by_table_name = {}
  models.each do |m|
    if !models_by_table_name.has_key?(m.table_name)
      models_by_table_name[m.table_name] = m
    elsif m.superclass==models_by_table_name[m.table_name].superclass.superclass
      # we need to ensure that models_by_table_name contains the
      # base class in an STI hierarchy
      models_by_table_name[m.table_name] = m
    end
  end
  # generate shims for HABTM models
  habtm_tables.each do |name, refls|
    models_by_table_name[name] = HabtmModelShim.from_reflection(refls.first)
  end
  model_table_names = models_by_table_name.keys

  to_create = model_table_names - db_tables
  to_drop = db_tables - model_table_names - always_ignore_tables
  to_change = model_table_names

  to_rename = extract_table_renames!(to_create, to_drop)

  renames = to_rename.map do |old_name, new_name|
    "rename_table :#{old_name}, :#{new_name}"
  end * "\n"
  undo_renames = to_rename.map do |old_name, new_name|
    "rename_table :#{new_name}, :#{old_name}"
  end * "\n"

  drops = to_drop.map do |t|
    "drop_table :#{t}"
  end * "\n"
  undo_drops = to_drop.map do |t|
    revert_table(t)
  end * "\n\n"

  creates = to_create.map do |t|
    create_table(models_by_table_name[t])
  end * "\n\n"
  undo_creates = to_create.map do |t|
    "drop_table :#{t}"
  end * "\n"

  changes = []
  undo_changes = []
  index_changes = []
  undo_index_changes = []
  to_change.each do |t|
    model = models_by_table_name[t]
    table = to_rename.key(t) || model.table_name
    if table.in?(db_tables)
      change, undo, index_change, undo_index = change_table(model, table)
      changes << change
      undo_changes << undo
      index_changes << index_change
      undo_index_changes << undo_index
    end
  end

  up   = [renames, drops, creates, changes, index_changes].flatten.reject(&:blank?) * "\n\n"
  down = [undo_changes, undo_renames, undo_drops, undo_creates, undo_index_changes].flatten.reject(&:blank?) * "\n\n"

  [up, down]
end

#habtm_tables ⇒ Object

list habtm join tables



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# File 'lib/hobo_fields/migration_generator.rb', line 103

def habtm_tables
  reflections = Hash.new { |h, k| h[k] = Array.new }
  ActiveRecord::Base.send(:subclasses).map do |c|
    c.reflect_on_all_associations(:has_and_belongs_to_many).each do |a|
      reflections[a.options[:join_table].to_s] << a
    end
  end
  reflections
end

#load_rails_models ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 65

def load_rails_models
  if defined? RAILS_ROOT
    Dir["#{RAILS_ROOT}/app/models/**/[a-z0-9_]*.rb"].each do |f|
      _, filename = *f.match(%r{/app/models/([_a-z0-9/]*).rb$})
      filename.camelize.constantize
    end
  end
end

#models_and_tables ⇒ Object

Returns an array of model classes and an array of table names that generation needs to take into account



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# File 'lib/hobo_fields/migration_generator.rb', line 115

def models_and_tables
  ignore_model_names = MigrationGenerator.ignore_models.*.to_s.*.underscore
  all_models = table_model_classes
  hobo_models = all_models.select { |m| m.try.include_in_migration && m.name.underscore.not_in?(ignore_model_names) }
  non_hobo_models = all_models - hobo_models
  db_tables = connection.tables - MigrationGenerator.ignore_tables.*.to_s - non_hobo_models.*.table_name
  [hobo_models, db_tables]
end

#native_types ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 100

def native_types; self.class.native_types; end

#revert_column(table, column) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 422

def revert_column(table, column)
  type, options = column_options_from_reverted_table(table, column)
  "add_column :#{table}, :#{column}, #{type}#{', ' + options.strip if options}"
end

#revert_table(table) ⇒ Object 



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# File 'lib/hobo_fields/migration_generator.rb', line 395

def revert_table(table)
  res = StringIO.new
  ActiveRecord::SchemaDumper.send(:new, ActiveRecord::Base.connection).send(:table, table, res)
  res.string.strip.gsub("\n  ", "\n")
end

#table_model_classes ⇒ Object

Returns an array of model classes that directly extend ActiveRecord::Base, excluding anything in the CGI module



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# File 'lib/hobo_fields/migration_generator.rb', line 77

def table_model_classes
  load_rails_models
  ActiveRecord::Base.send(:subclasses).reject {|c| (c.base_class != c) || c.name.starts_with?("CGI::") }
end