Class: Replicator::Trigger

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(table, opts) ⇒ Trigger

Returns a new instance of Trigger.



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# File 'lib/replicator.rb', line 57

def initialize(table, opts)
  @from       = table
  @to         = opts[:to]
  @name       = opts[:name]
  @key        = opts[:key] || 'id'
  @condition  = opts[:condition] || opts[:if]
  @prefix     = opts[:prefix]
  @prefix_map = opts[:prefix_map]
  @timestamps = opts[:timestamps]
  @dependent  = opts[:dependent]

  if opts[:through]
    @through_table, @through_key = opts[:through].split('.')
    raise "through must be of the form 'table.field'" unless @through_table and @through_key
  end

  # Use opts[:prefixes] to specify valid prefixes and use the identity mapping.
  if @prefix_map.nil? and opts[:prefixes]
    @prefix_map = {}
    opts[:prefixes].each do |prefix|
      @prefix_map[prefix] = prefix
    end
  end

  if @prefix_map
    @prefix, prefix_table = @prefix.split('.').reverse
    
    if prefix_table.nil? or prefix_table == from
      @prefix_through = false
    elsif prefix_table == through_table
      @prefix_through = true
    else
      "unknown prefix table: #{prefix_table}" 
    end
  end

  @fields = {}
  opts[:fields] = [opts[:fields]] unless opts[:fields].kind_of?(Array)
  opts[:fields].each do |field|
    if field.kind_of?(Hash)
      @fields.merge!(field)
    else
      @fields[field] = field
    end
  end
end

Instance Attribute Details

#condition ⇒ Object (readonly)

Returns the value of attribute condition.



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# File 'lib/replicator.rb', line 55

def condition
  @condition
end

#dependent ⇒ Object (readonly)

Returns the value of attribute dependent.



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# File 'lib/replicator.rb', line 55

def dependent
  @dependent
end

#from ⇒ Object (readonly)

Returns the value of attribute from.



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# File 'lib/replicator.rb', line 55

def from
  @from
end

#key ⇒ Object (readonly)

Returns the value of attribute key.



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# File 'lib/replicator.rb', line 55

def key
  @key
end

#prefix ⇒ Object (readonly)

Returns the value of attribute prefix.



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# File 'lib/replicator.rb', line 55

def prefix
  @prefix
end

#prefix_map ⇒ Object (readonly)

Returns the value of attribute prefix_map.



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# File 'lib/replicator.rb', line 55

def prefix_map
  @prefix_map
end

#through_key ⇒ Object (readonly)

Returns the value of attribute through_key.



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# File 'lib/replicator.rb', line 55

def through_key
  @through_key
end

#through_table ⇒ Object (readonly)

Returns the value of attribute through_table.



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# File 'lib/replicator.rb', line 55

def through_table
  @through_table
end

#to ⇒ Object (readonly)

Returns the value of attribute to.



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# File 'lib/replicator.rb', line 55

def to
  @to
end

Instance Method Details

#create_sql ⇒ Object 



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# File 'lib/replicator.rb', line 123

def create_sql
  %{
    CREATE OR REPLACE FUNCTION #{name}() RETURNS TRIGGER AS $$
      DECLARE
        ROW     RECORD;
        THROUGH RECORD;
      BEGIN
        IF (TG_OP = 'DELETE') THEN
          ROW := OLD;
        ELSE
          ROW := NEW;
        END IF;
        #{loop_sql}
          IF #{conditions_sql} THEN
            IF (TG_OP = 'DELETE') THEN
              #{delete_sql(:indent => 18)}
            ELSE
              IF COUNT(*) = 0 FROM #{to} WHERE id = #{primary_key} THEN
                #{insert_sql}
              END IF;
              #{update_all_sql(:indent => 18)}
            END IF;
          END IF;
        #{end_loop_sql}
        RETURN NULL;
      END;
    $$ LANGUAGE plpgsql;
    CREATE TRIGGER #{name} AFTER INSERT OR UPDATE OR DELETE ON #{from}
      FOR EACH ROW EXECUTE PROCEDURE #{name}();
  }
end

#drop_sql ⇒ Object 



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# File 'lib/replicator.rb', line 198

def drop_sql
  "DROP FUNCTION IF EXISTS #{name}() CASCADE"
end

#fields(opts = nil) ⇒ Object 



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# File 'lib/replicator.rb', line 104

def fields(opts = nil)
  if opts
    opts[:row] ||= 'ROW'
    # Add the prefixes and return an array of arrays.
    @fields.collect do |from_field, to_field|
      if from_field.kind_of?(Array)
        from_field = from_field.collect {|f| "COALESCE(#{opts[:row]}.#{f}, '')"}.join(" || ' ' || ") 
      else
        from_field = "#{opts[:row]}.#{from_field}"
      end
      to_field = [opts[:prefix], to_field].compact.join('_')
      [from_field, to_field]
    end
  else
    # Just return the hash.
    @fields
  end
end

#initialize_sql ⇒ Object 



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# File 'lib/replicator.rb', line 155

def initialize_sql
  sql_by_slice = {}
  
  if through?
    tables = "#{from}, #{through_table}"
    join   = "#{from}.id = #{through_table}.#{through_key}"
  else
    tables = from
  end

  if prefix_map
    prefix_map.each do |prefix_value, mapping|
      slice_fields = []
      field_sql = fields(:prefix => mapping, :row => from).collect do |from_field, to_field|
        slice_fields << to_field
        "#{from_field} AS #{to_field}"
      end.join(', ')
      where_sql  = "WHERE " << [join, "#{prefix_field(true)} = '#{prefix_value}'"].compact.join(' AND ')
      table_name = "#{name}_#{mapping}"
      
      slice = {:name => table_name, :fields => slice_fields}
      sql_by_slice[slice] = %{
        CREATE TABLE #{table_name} AS
          SELECT #{primary_key(true)} AS id, #{field_sql} FROM #{tables} #{where_sql}
      }
    end
  else
    slice_fields = []
    field_sql = fields(:prefix => prefix, :row => from).collect do |from_field, to_field|
      slice_fields << to_field
      "#{from_field} AS #{to_field}"
    end.join(', ')
    where_sql  = "WHERE #{join}" if join
    
    slice = {:name => name, :fields => slice_fields}
    sql_by_slice[slice] = %{
      CREATE TABLE #{name} AS
        SELECT #{primary_key(true)} AS id, #{field_sql} FROM #{tables} #{where_sql}
    }
  end
  sql_by_slice
end

#prefix_through? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/replicator.rb', line 210

def prefix_through?
  @prefix_through
end

#through? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/replicator.rb', line 206

def through?
  not through_table.nil?
end

#timestamps? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/replicator.rb', line 202

def timestamps?
  @timestamps
end