{"id":997,"date":"2022-08-30T15:10:40","date_gmt":"2022-08-30T15:10:40","guid":{"rendered":"https:\/\/unknownerror.org\/index.php\/2013\/11\/09\/rails-has_many-through-with-conditions-on-aliased-association-collection-of-common-programming-errors\/"},"modified":"2022-08-30T15:10:40","modified_gmt":"2022-08-30T15:10:40","slug":"rails-has_many-through-with-conditions-on-aliased-association-collection-of-common-programming-errors","status":"publish","type":"post","link":"https:\/\/unknownerror.org\/index.php\/2022\/08\/30\/rails-has_many-through-with-conditions-on-aliased-association-collection-of-common-programming-errors\/","title":{"rendered":"rails has_many :through with conditions on aliased association-Collection of common programming errors"},"content":{"rendered":"

This kind of goes along with my original question about has_many :through<\/code> with conditions, but I’ve found another problem.<\/p>\n

Given this class:<\/p>\n

class Contact < AR\n  has_many :group_contacts\n  has_many :groups, :through => :group_contacts, :conditions => {:published => true}\n  has_many :anonymous_groups, :through => :group_contacts, :source => :group, :conditions => {:anonymous => true}\nend\n<\/code><\/pre>\n
My problem happens when I try to include the anonymous_groups<\/code> with contacts<\/code>:<\/p>\n
Contact.includes(:anonymous_groups)\n<\/code><\/pre>\n
\n
ActiveRecord::StatementInvalid: PGError: ERROR: missing FROM-clause entry for table “contacts”<\/p>\n<\/blockquote>\n
The reason for this is the generated sql is incorrect. It’s something akin to:<\/p>\n
SELECT \"group_contacts\".\"id\" AS t0_r0 ... \"groups\".\"anonymous\" AS t1_r5 ... LEFT OUTER JOIN \"groups\" ON \"groups\".\"id\" = \"group_contacts\".\"group_id\" WHERE (\"group_contacts\".contact_id IN (...) AND (\"contacts\".\"anonymous\" = 'true'))\n<\/code><\/pre>\n
Paraphrased of course, but look at the final condition. It’s put the anonymous condition on contacts<\/code> rather than groups<\/code><\/p>\n
Now, we can alleviate this query error (which i’m sure is a bug) but doing something like:<\/p>\n
has_many :anonymous_groups, :through => :group_challenges, :source => :group, :conditions => { :groups => {:anonymous => :true} }\n<\/code><\/pre>\n
This puts the condition on the correct table in sql, but when I try to build an anonymous group, I get this:<\/p>\n
contact.anonymous_groups.build\n<\/code><\/pre>\n
\n
ActiveRecord::UnknownAttributeError: unknown attribute: groups.anonymous<\/p>\n<\/blockquote>\n
So it works for querying but not for building. I’m quite certain this is a bug, but I’m wondering if anyone else has experienced this or has a workaround.<\/p>\n
    \n
  1. \n
    I think something like :conditions => \"groups.anonymous = true\"<\/code> should work fine.<\/p>\n<\/li>\n<\/ol>\n
    Originally posted 2013-11-09 23:12:02. <\/small><\/p>","protected":false},"excerpt":{"rendered":"
    This kind of goes along with my original question about has_many :through with conditions, but I’ve found another problem. Given this class: class Contact < AR has_many :group_contacts has_many :groups, :through => :group_contacts, :conditions => {:published => true} has_many :anonymous_groups, :through => :group_contacts, :source => :group, :conditions => {:anonymous => true} end My problem happens […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-997","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/997","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=997"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/997\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=997"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=997"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=997"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}