Class: Rmre::Migrator

Inherits:
Object
  • Object
show all
Defined in:
lib/rmre/migrator.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(source_db_options, target_db_options, options = {}) ⇒ Migrator

Returns a new instance of Migrator.



25
26
27
28
29
30
31
32
33
34
35
36
 
# File 'lib/rmre/migrator.rb', line 25

def initialize(source_db_options, target_db_options, options = {})
  # If set to true will call AR create_table with force (table will be dropped if exists)
  @force_table_create = false
  @skip_existing_tables = options[:skip_existing]
  @verbose = options[:verbose]
  @before_copy = nil

  Rmre::Source.connection_options = source_db_options
  Rmre::Target.connection_options = target_db_options
  Rmre::Source::Db.establish_connection(Rmre::Source.connection_options)
  Rmre::Target::Db.establish_connection(Rmre::Target.connection_options)
end

Instance Attribute Details

#before_copy ⇒ Object

Returns the value of attribute before_copy.



23
24
25
 
# File 'lib/rmre/migrator.rb', line 23

def before_copy
  @before_copy
end

Instance Method Details

#copy(force = false) ⇒ Object

Before we start copying we call block if it is given so some additional options can be set. For example MS SQL adapter has option to use lowercase names for all entities. We can set this options in a following way:

mig = Migrator.new(..) mig.copy(true) do

ActiveRecord::ConnectionAdapters::SQLServerAdapter.lowercase_schema_reflection = true

end



46
47
48
49
50
51
52
53
54
55
 
# File 'lib/rmre/migrator.rb', line 46

def copy(force = false)
  yield if block_given?

  @force_table_create = force
  tables_count = Rmre::Source::Db.connection.tables.length
  Rmre::Source::Db.connection.tables.sort.each_with_index do |table, idx|
    info "Copying table #{table} (#{idx + 1}/#{tables_count})..."
    copy_table(table)
  end
end

#copy_data(table_name) ⇒ Object 



118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
 
# File 'lib/rmre/migrator.rb', line 118

def copy_data(table_name)
  primary_key = Rmre::Source::Db.connection.primary_key(table_name)

  src_model = Rmre::Source.create_model_for(table_name, primary_key)
  src_model.inheritance_column = 'ruby_type' if table_has_type_column(table_name)
  tgt_model = Rmre::Target.create_model_for(table_name, primary_key)

  rec_count = src_model.count
  # We will always copy attributes without protection because we
  # are the ones initiating DB copy (no need to preform additional checks)
  progress_bar = Console::ProgressBar.new(table_name, rec_count) if @verbose
  src_model.all.each do |src_rec|
    tgt_model.create!(src_rec.attributes, :without_protection => true)
    progress_bar.inc if @verbose
  end
end

#copy_table(table) ⇒ Object 



57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
 
# File 'lib/rmre/migrator.rb', line 57

def copy_table(table)
  if @skip_existing_tables && Rmre::Target::Db.connection.table_exists?(table)
    info "Skipping #{table}"
    return
  end

  if before_copy && before_copy.is_a?(Proc)
    return unless before_copy.call(table)
  end

  if !Rmre::Target::Db.connection.table_exists?(table) || @force_table_create
    create_table(table, Rmre::Source::Db.connection.columns(table))
  end
  copy_data(table)
end

#create_table(table, source_columns) ⇒ Object 



73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
 
# File 'lib/rmre/migrator.rb', line 73

def create_table(table, source_columns)
  primary_key = Rmre::Source::Db.connection.primary_key(table)

  # Create primary key if source table has primary key
  opts = { :id => !primary_key.nil?, :force => @force_table_create }
  # If primary key is not 'id' then set option to create proper primary key
  opts[:primary_key] = primary_key unless primary_key == "id"

  Rmre::Target::Db.connection.create_table(table, opts) do |t|
    # Skip 'id' column if it is already created as primary key
    source_columns.reject {|col| col.name == 'id' && opts[:id] && opts[:primary_key].nil? }.each do |sc|
      options = {
        :null => sc.null,
        :default => sc.default
      }

      # Some adapters do not convert all types to Rails value. Example is oracle_enhanced adapter
      # which for 'LONG' column type sets column's type to nil but keeps sql_type as 'LONG'.
      # Therefore we will use one of these values so we can, in DbUtils, handle all possible
      # column type mappings when we are migrating from one DB to anohter (Oracle -> MySQL,
      # MS SQL -> PostgreSQL, etc).
      source_type = sc.type.nil? ? sc.sql_type : sc.type
      col_type = Rmre::DbUtils.convert_column_type(Rmre::Target::Db.connection.adapter_name, source_type)
      case col_type
      when :decimal
        options.merge!({
            :limit => sc.limit,
            :precision => sc.precision,
            :scale => sc.scale,
          })
      when :string
        options.merge!({
            :limit => sc.limit
          })
      end

      t.column(sc.name, col_type, options)
    end
  end
end

#table_has_type_column(table) ⇒ Object 



114
115
116
 
# File 'lib/rmre/migrator.rb', line 114

def table_has_type_column(table)
  Rmre::Source::Db.connection.columns(table).find {|col| col.name == 'type'}
end