ruby-on-rails - group_by 和计数

Question

@entries_by_source = Entry.joins(:training_entries).group("source_id, classification_id, category_id").select("source_id, classification_id, category_id, count(*) as entries_count")

这些在@entires_by_source 中

- !ruby/ActiveRecord:Entry 
  attributes: 
    source_id: 1
    classification_id: 1
    category_id: 1
    entries_count: 198
- !ruby/ActiveRecord:Entry 
  attributes: 
    source_id: 1
    classification_id: 1
    category_id: 2
    entries_count: 614
- !ruby/ActiveRecord:Entry 
  attributes: 
    source_id: 2
    classification_id: 1
    category_id: 3
    entries_count: 1

现在我正在尝试打印类似的东西:

source_id entries_count
1          812 #sum of entries_count 198 + 614
2          1

下面的代码不起作用。任何帮助将不胜感激

<% @entries_by_source.group_by(&:source_id).each do |source_id, entries_count| %>
  <%= source_id %><%= entries_count %>
<% end %>

Answer 1

group_by 将返回一个数组，如
[{'source_id_1' => [values, ...]}, {'source_id_2' => [values, ...]}]
您需要对计数求和，例如:

<% @entries_by_source.group_by(&:source_id).each do |source_id, entries| %>
  <%= source_id %><%= entries.sum(&:entries_count) %>
<% end %>