Module: Repertoire::Faceting::Facets::NestedFacet

Includes:
Arel, AbstractFacet
Defined in:
lib/repertoire-faceting/facets/nested_facet.rb

Overview

Implementation of AbstractFacet for facets whose values fall into a nested taxonomy. By default, all facets that group several columns will follow this behavior.

See Repertoire::Faceting::Model::ClassMethods for usage.

Instance Attribute Summary

Attributes included from AbstractFacet

#facet_name

Class Method Summary collapse

Instance Method Summary collapse

Methods included from AbstractFacet

#drop_index, #facet_indexed?, #refresh_index

Class Method Details

.claim?(relation) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/repertoire-faceting/facets/nested_facet.rb', line 14

def self.claim?(relation)
  relation.group_values.size > 1
end

Instance Method Details

#create_index ⇒ Object 



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# File 'lib/repertoire-faceting/facets/nested_facet.rb', line 36

def create_index
  levels = group_values.length

  # Construct expressions at each grouping level, right pad with nil
  expr_drills = (0..levels-1).map do |i|
    group_values[0..i] + (i+1..levels-1).collect { "NULL" }
  end

  # Construct indexes for each drill level
  queries = []
  expr_drills.each_with_index do |exprs, level|
    rel = only(:where, :joins)
    exprs.zip(columns).each do |expr, col|
      rel = rel.select("#{expr} AS #{col}")
    end
    rel = rel.group(columns[0..level])

    queries << rel.select(["#{level+1} AS level", "facet.signature(#{table_name}.#{faceting_id})"]).to_sql
  end

  # Root of tree
  empty_cols = columns.map { |col| "NULL AS #{col}"}
  queries << only(:where).select(empty_cols + ["0 AS level", "facet.signature(#{table_name}.#{faceting_id})"]).to_sql

  # Give the fullest index first (i.e. leaves of the tree), so the database
  # can resolve types before encountering any NULL values (i.e. values of
  # indeterminate type)
  queries = queries.reverse

  # The full index table is union of indices at each drill level
  sql = queries.join(" UNION ")

  connection.create_materialized_view(facet_index_name, sql)
end

#drill(state) ⇒ Object 



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# File 'lib/repertoire-faceting/facets/nested_facet.rb', line 27

def drill(state)
  return read_index(state, false) if facet_indexed?
  rel = only(:where, :joins)
  grp = bind_nest(group_values, state) do |expr, val|
    rel = rel.where("#{expr} = #{connection.quote(val)}")
  end
  rel.group(grp).select(["#{grp.last} AS #{facet_name}", "facet.signature(#{table_name}.#{faceting_id})"]).arel
end

#signature(state) ⇒ Object 



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# File 'lib/repertoire-faceting/facets/nested_facet.rb', line 18

def signature(state)
  return read_index(state, true) if facet_indexed?
  rel = only(:where, :joins)
  bind_nest(group_values, state) do |expr, val|
    rel = rel.where("#{expr} = #{connection.quote(val)}")
  end
  rel.select("facet.signature(#{table_name}.#{faceting_id})").arel
end