Module: ActiveRecord::CollectionCacheKey

Included in:
Base
Defined in:
activerecord/lib/active_record/collection_cache_key.rb

Instance Method Summary collapse

Instance Method Details

#collection_cache_key(collection = all, timestamp_column = :updated_at) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/collection_cache_key.rb', line 4

def collection_cache_key(collection = all, timestamp_column = :updated_at) # :nodoc:
  query_signature = Digest::MD5.hexdigest(collection.to_sql)
  key = "#{collection.model_name.cache_key}/query-#{query_signature}"

  if collection.loaded?
    size = collection.size
    if size > 0
      timestamp = collection.max_by(&timestamp_column).public_send(timestamp_column)
    end
  else
    column_type = type_for_attribute(timestamp_column.to_s)
    column = "#{connection.quote_table_name(collection.table_name)}.#{connection.quote_column_name(timestamp_column)}"

    query = collection
      .unscope(:select)
      .select("COUNT(*) AS #{connection.quote_column_name("size")}", "MAX(#{column}) AS timestamp")
      .unscope(:order)
    result = connection.select_one(query)

    if result.blank?
      size = 0
      timestamp = nil
    else
      size = result["size"]
      timestamp = column_type.deserialize(result["timestamp"])
    end

  end

  if timestamp
    "#{key}-#{size}-#{timestamp.utc.to_s(cache_timestamp_format)}"
  else
    "#{key}-#{size}"
  end
end