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POAn ActiveRecord has its `id` == nil after saving
 

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  1. POAn ActiveRecord has its `id` == nil after saving
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    <p>It is really awkward that the <code>id</code> of an ActiveRecord is still <code>nil</code> after <code>save</code>.</p> <p>My command in console is as follows:</p> <pre><code>irb(main):003:0&gt; c = Comment.new =&gt; #&lt;Comment id: nil, commentable_id: nil, commentable_type: nil, user_id: nil, content: "", del_flg: 0, created_at: nil&gt; irb(main):004:0&gt; c.commentable = Moment.last Moment Load (0.2ms) SELECT `moments`.* FROM `moments` ORDER BY `moments`.`id` DESC LIMIT 1 =&gt; #&lt;Moment id: 119583... irb(main):005:0&gt; c.user = User.find(119) User Load (0.2ms) SELECT `users`.* FROM `users` WHERE `users`.`id` = 119 LIMIT 1 =&gt; #&lt;User id: 119... irb(main):006:0&gt; c.save (0.2ms) BEGIN SQL (0.6ms) INSERT INTO `comments` (`commentable_id`, `commentable_type`, `content`, `created_at`, `del_flg`, `id`, `user_id`) VALUES (119583, 'Moment', '', '2013-01-22 15:19:05', 0, NULL, 119) (0.1ms) COMMIT =&gt; true irb(main):007:0&gt; c =&gt; #&lt;Comment id: nil, commentable_id: 119583, commentable_type: "Moment", user_id: 119, content: "", del_flg: 0, created_at: "2013-01-22 15:19:05"&gt; irb(main):008:0&gt; c.id =&gt; nil </code></pre> <p>This is how I defined my record:</p> <pre><code>class Comment &lt; ActiveRecord::Base belongs_to :user belongs_to :commentable, polymorphic: true end </code></pre> <p>At first, I thought it was that <code>id</code> is not set to the <code>PRIMARY KEY</code> in my MySQL database, so I checked it:</p> <pre><code> mysql&gt; describe comments; +------------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | commentable_id | int(11) | NO | MUL | NULL | | | commentable_type | varchar(100) | NO | MUL | NULL | | | user_id | int(11) | NO | | NULL | | | content | text | NO | | NULL | | | del_flg | tinyint(4) | NO | | 0 | | | created_at | datetime | NO | | NULL | | +------------------+--------------+------+-----+---------+----------------+ </code></pre> <p>Anyone has any idea about how this would come? Thanks in advance.</p> <p><strong>EDIT</strong>:</p> <p>Just realize that the SQL explanation for <code>c.save</code> is <code>INSERT INTO <code>comments</code> (<code>commentable_id</code>, <code>commentable_type</code>, <code>content</code>, <code>created_at</code>, <code>del_flg</code>, <code>id</code>, <code>user_id</code>) VALUES (119583, 'Moment', '', '2013-01-22 15:19:05', 0, NULL, 119)</code></p> <p>Well, this record is in fact inserted into database.</p> <pre><code>mysql&gt; select * from comments where commentable_id = 119583 and commentable_type = "Moment" -&gt; ; +-------+----------------+------------------+---------+---------+---------+--------- ------------+ | id | commentable_id | commentable_type | user_id | content | del_flg | created_at | +-------+----------------+------------------+---------+---------+---------+---------------------+ | 26582 | 119583 | Moment | 119 | | 0 | 2013-01-22 14:58:22 | | 26583 | 119583 | Moment | 119 | | 0 | 2013-01-22 15:09:11 | | 26585 | 119583 | Moment | 119 | | 0 | 2013-01-22 15:19:05 | | 26586 | 119583 | Moment | 119 | | 0 | 2013-01-22 15:38:14 | +-------+----------------+------------------+---------+---------+---------+---------------------+ </code></pre> <p>More tests:</p> <pre><code>irb(main):009:0&gt; c.persisted? =&gt; true irb(main):010:0&gt; c.errors =&gt; #&lt;ActiveModel::Errors:0x00000004761958 @base=#&lt;Comment id: nil, commentable_id: 119583, commentable_type: "Moment", user_id: 119, content: "", del_flg: 0, created_at: "2013-01-22 16:52:59"&gt;, @messages={}&gt; </code></pre>
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    1. PTQuestion
    1. USChao Zhang
    1. USChao Zhang
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    1. COHmm... could be a dumb suggestion but it is worth checking that your development DB is what you think it is. Does rails db bring up the correct instance? Otherwise, I am stumped!!
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      1. USNazar
    2. COI am indeed using my development DB.
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      1. USChao Zhang
    3. COIs the record actually saved? Do you have a row with a NULL id?
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      1. USNazar
 

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