StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

POhas_many :through - sql statement using NULL id
primarykey
Id
10742608
data
AcceptedAnswerId
10755500
AnswerCount
2
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2012-05-24T17:40:31.813
FavoriteCount
0
LastActivityDate
2014-02-04T21:03:22.473
LastEditDate
LastEditorUserId
0
OwnerUserId
877472
ParentId
0
PostTypeId
1
Score
0
ViewCount
286
LastEditorDisplayName
text
Body
We recently upgraded our rails app from version 3.0.3 to 3.1.0. The application runs successfully for the most part as it did before with one major exception. We have a many-to-many relationship between two models, SurveyDatum and SubGroup, joined via a model called SubGroupSurveyDatum. Here is the code for each: <pre><code>class SurveyDatum < ActiveRecord::Base has_many :sub_group_survey_data has_many :sub_groups, :through => :sub_group_survey_data end class SubGroup < ActiveRecord::Base has_many :sub_group_survey_data has_many :survey_data, :through => :sub_group_survey_data end </code></pre> And as you might expect: <pre><code>class SubGroupSurveyDatum < ActiveRecord::Base belongs_to :survey_datum belongs_to :sub_group end </code></pre> If I have a SurveyDatum object that I retrieved previously from the database (lets call it 'sd'), and I invoke the sub_groups method (sd.sub_groups), this is the resulting sql query generated by active record: <pre><code>SELECT `sub_groups`.* FROM `sub_groups` INNER JOIN `sub_group_survey_data` ON `sub_groups`.`id` = `sub_group_survey_data`.`sub_group_id` WHERE `sub_group_survey_data`.`survey_datum_id` IS NULL </code></pre> The "IS NULL" part is obviously where the id of my survey data object is supposed to go, however active record fails to use it. The object does indeed have an id, since as mentioned it was persisted and retrieved from the database. This problem only cropped up after we moved to rails 3.1, so I assume there's something I've not done properly in accordance with the new version, but I have no idea. Any ideas? Thank you in advance for your help!
Tags
<ruby-on-rails><activerecord><ruby-on-rails-3.1>
Title
has_many :through - sql statement using NULL id
singulars
PostAcceptedAnswerId
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USPaul Richter
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
2. PO
 singulars
 PostTypePostTypeId
 PTAnswer
VotesPostIdCreationDate
1. This table or related slice is empty.
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.