Module: Sequel::GraphEach

Defined in:
lib/sequel/extensions/graph_each.rb

Instance Method Summary collapse

Instance Method Details

#graph_each ⇒ Object

Fetch the rows, split them into component table parts, tranform and run the row_proc on each part (if applicable), and yield a hash of the parts.



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# File 'lib/sequel/extensions/graph_each.rb', line 23

def graph_each
  # Reject tables with nil datasets, as they are excluded from
  # the result set
  datasets = @opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?}
  # Get just the list of table aliases into a local variable, for speed
  table_aliases = datasets.collect{|ta,ds| ta}
  # Get an array of arrays, one for each dataset, with
  # the necessary information about each dataset, for speed
  datasets = datasets.collect{|ta, ds| [ta, ds, ds.row_proc]}
  # Use the manually set graph aliases, if any, otherwise
  # use the ones automatically created by .graph
  column_aliases = @opts[:graph_aliases] || @opts[:graph][:column_aliases]
  fetch_rows(select_sql) do |r|
    graph = {}
    # Create the sub hashes, one per table
    table_aliases.each{|ta| graph[ta]={}}
    # Split the result set based on the column aliases
    # If there are columns in the result set that are
    # not in column_aliases, they are ignored
    column_aliases.each do |col_alias, tc|
      ta, column = tc
      graph[ta][column] = r[col_alias]
    end
    # For each dataset run the row_proc if applicable
    datasets.each do |ta,ds,rp|
      g = graph[ta]
      graph[ta] = if g.values.any?{|x| !x.nil?}
        rp ? rp.call(g) : g
      else
        nil
      end
    end

    yield graph
  end
  self
end