Class: MyDiff::Change

Inherits:
Object
  • Object
show all
Defined in:
lib/mydiff/change.rb

Overview

Represents one change to apply to the database

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(parent, type, table) ⇒ Change

Create a new change for a specific table

parent

the MyDiff parent class

type

one of :new, :drop, :overwrite or :patch

table

the table to change



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# File 'lib/mydiff/change.rb', line 15

def initialize(parent, type, table)
  @md = parent
  @type = type
  @table = table
  @chunks = {}
end

Instance Attribute Details

#chunks ⇒ Object

Returns the value of attribute chunks.



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# File 'lib/mydiff/change.rb', line 8

def chunks
  @chunks
end

#type ⇒ Object

Can be one of :new, :drop, :overwrite or :patch



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# File 'lib/mydiff/change.rb', line 7

def type
  @type
end

Instance Method Details

#add_chunk(type, pkey, fields = {}) ⇒ Object

Adds a chunk to apply in the change.

type

can be either :new, :delete or :change

pkey

should be a hash containing primary key fields

fields

should be a hash containint the fields not belonging to primary key (only for type = :new or :change)

Raises:

  • (ArgumentError) 


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# File 'lib/mydiff/change.rb', line 27

def add_chunk(type, pkey, fields = {})
  raise ArgumentError, "Chunks can be added only if type is :patch" unless @type.eql?(:patch)
  @chunks[pkey.to_yaml] = { :type => type, :pkey => pkey, :fields => fields}
end

#apply! ⇒ Object 



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# File 'lib/mydiff/change.rb', line 44

def apply!
  if @type.eql?(:new)
    puts "** Creating #{@table}"
    @md.select_old
    @md.my.query("CREATE TABLE #{@table} LIKE #{@md.newdb}.#{@table}")
    @md.my.query("INSERT INTO #{@table} SELECT * FROM #{@md.newdb}.#{@table}")
  elsif @type.eql?(:drop)
    puts "** Dropping table #{@table}"
    @md.select_old
    @md.my.query("DROP TABLE #{@table}")
  elsif @type.eql?(:overwrite)
    raise NotImplementedError, "Type :overwrite is not yet in use"
  elsif @type.eql?(:patch)
    printf "** Updating table #{@table}"
    @chunks.each_pair do |pkey, data|
      printf "."
      @md.select_old
      if data[:type].eql?(:new)
        field_list = []
        data_list = []
        data[:pkey].each_pair do |k,v|
          field_list << k
          data_list << "'" + @md.my.escape_string(v) + "'"
        end
        data[:fields].each_pair do |k,v|
          field_list << k
          data_list << "'" + @md.my.escape_string(v) + "'"
        end
        
        puts("INSERT INTO #{@table} (#{field_list.join(',')}) VALUES(#{data_list.join(',')})") if $DEBUG
        @md.my.query("INSERT INTO #{@table} (#{field_list.join(',')}) VALUES(#{data_list.join(',')})")
      elsif data[:type].eql?(:change)
        changes_list = []
        pkey_list = []
        data[:pkey].each_pair do |k,v|
          pkey_list << "#{k} = '" + @md.my.escape_string(v) + "'"
        end
        data[:fields].each_pair do |k,v|
          changes_list << "#{k} = '" + @md.my.escape_string(v) + "'"
        end
        
        puts("UPDATE #{@table} SET #{changes_list.join(',')} WHERE #{pkey_list.join(' AND ')}") if $DEBUG
        @md.my.query("UPDATE #{@table} SET #{changes_list.join(',')} WHERE #{pkey_list.join(' AND ')}")
      elsif data[:type].eql?(:delete)
        pkey_list = []
        data[:pkey].each_pair do |k,v|
          pkey_list << "#{k} = '" + @md.my.escape_string(v) + "'"
        end
        puts("DELETE FROM #{@table} WHERE #{pkey_list.join(' AND ')}") if $DEBUG
        @md.my.query("DELETE FROM #{@table} WHERE #{pkey_list.join(' AND ')}")
      else
        raise NotImplementedError, "Invalid chunk type: #{data[:type]}"
      end
    end
    
    puts
  else
    raise NotImplementedError, "Invalid type #{@type.to_s}"
  end
end

#delete_chunk(pkey) ⇒ Object 



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# File 'lib/mydiff/change.rb', line 32

def delete_chunk(pkey)
  @chunks.delete(pkey.to_yaml)
end

#get_chunk(pkey) ⇒ Object 



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# File 'lib/mydiff/change.rb', line 36

def get_chunk(pkey)
  @chunks[pkey.to_yaml]
end

#has_chunk?(pkey) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/mydiff/change.rb', line 40

def has_chunk?(pkey)
  @chunks.has_key?(pkey.to_yaml)
end