Class: Tiler::Widgets::PieChartQuery

Inherits:
Query::Base show all
Defined in:
lib/tiler/widgets/pie_chart.rb

Constant Summary collapse

DEFAULT_LIMIT = 
6
OTHER_LABEL = 
"Other".freeze

Constants inherited from Query::Base

Query::Base::SAFE_COLUMN_RE

Instance Attribute Summary

Attributes inherited from Query::Base

#config, #panel, #source

Instance Method Summary collapse

Methods inherited from Query::Base

#initialize

Constructor Details

This class inherits a constructor from Tiler::Query::Base

Instance Method Details

#call ⇒ Object 



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# File 'lib/tiler/widgets/pie_chart.rb', line 10

def call
  group_col = config["group_column"]
  agg       = config["aggregation"] || "count"
  val_col   = config["value_column"]
  limit     = (config["limit"] || DEFAULT_LIMIT).to_i.clamp(1, 50)

  return empty_result if group_col.blank?

  # Aggregate every group, then sort descending by value so the largest
  # slices win the visible spots. Anything past `limit` collapses into a
  # single "Other" slice (only when there's actually overflow).
  groups = distinct_values(group_col)
  all_pairs = groups.map { |g| [ g, aggregate_for_group(group_col, g, val_col, agg).to_f ] }
                    .sort_by { |(_, v)| -v }

  kept     = all_pairs.first(limit)
  leftover = all_pairs.drop(limit)

  labels = kept.map(&:first)
  data   = kept.map(&:last)
  if leftover.any?
    other_value = leftover.sum { |(_, v)| v }
    if other_value > 0
      labels << OTHER_LABEL
      data   << other_value
    end
  end

  colors = labels.each_index.map { |i| chart_colors[i % chart_colors.size] }
  # Legend on the right at panel widths >= 4 cols (catalog spec); top
  # otherwise so the slices keep room to breathe in narrow tiles.
  legend_pos = panel.width.to_i >= 4 ? "right" : "top"

  {
    labels:   labels,
    datasets: [ { data: data, backgroundColor: colors.map { |c| "#{c}cc" },
                  borderColor: colors, borderWidth: 2 } ],
    options: {
      plugins: { legend: { position: legend_pos } }
    }
  }
end