Question

当我尝试做一个香草find_each时，它会一直返回nil，即使有应该作用的对象/记录。

[28] pry(main)> Node.find_each do |node|
[28] pry(main)* end  
  Node Load (1.0ms)  SELECT  "nodes".* FROM "nodes"   ORDER BY "nodes"."id" ASC LIMIT 1000
=> nil
[29] pry(main)> Node.all.find_each do |node|
[29] pry(main)*   node
[29] pry(main)* end  
  Node Load (0.7ms)  SELECT  "nodes".* FROM "nodes"   ORDER BY "nodes"."id" ASC LIMIT 1000
=> nil
[31] pry(main)> Node.count
   (0.5ms)  SELECT COUNT(*) FROM "nodes"
=> 2
[32] pry(main)> Node.find_each do |node|
[32] pry(main)*   puts node
[32] pry(main)* end  
  Node Load (0.5ms)  SELECT  "nodes".* FROM "nodes"   ORDER BY "nodes"."id" ASC LIMIT 1000
#<Node:0x007fd49ffbc680>
#<Node:0x007fd49ffbc388>
=> nil

如何让find_each简单地输出该模型的所有对象，就像Node.all那样，为什么它只输出看似每个节点的AR对象的ID，只有当我做了puts node？

[35] pry(main)> Node.all
  Node Load (0.4ms)  SELECT "nodes".* FROM "nodes"
=> [#<Node id: 85, name: "House Fire 2", family_tree_id: 57, user_id: 57, media_id: 228, media_type: "Video", created_at: "2015-05-15 00:20:26", updated_at: "2015-05-20 01:06:34", circa: nil, is_comment: nil, cached_votes_total: 0, cached_votes_score: 0, cached_votes_up: 0, cached_votes_down: 0, cached_weighted_score: 0, cached_weighted_total: 0, cached_weighted_average: 0.0>,
 #<Node id: 86, name: "10PP Form Video", family_tree_id: 57, user_id: 57, media_id: 229, media_type: "Video", created_at: "2015-05-15 01:26:28", updated_at: "2015-05-22 20:35:58", circa: nil, is_comment: nil, cached_votes_total: 1, cached_votes_score: 1, cached_votes_up: 1, cached_votes_down: 0, cached_weighted_score: 1, cached_weighted_total: 1, cached_weighted_average: 0.0>]

Answer 1

> Node.find_each do |node|
> end 
 => nil

在这种情况下，nil来自该块的定义;不是Node.find_each的结果。

尝试按如下方式在块中打印出来：

> Node.find_each do |node|
>  puts node.id
> end

这将打印出2个ID。

打印出所有对象：

> Node.find_each do |node|
>  puts node.inspect
> end

为什么find_each不返回实际的AR对象？

1 个答案: