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我正在使用 Rails 3.2.8 进行开发，并希望通过多个关系计数的总和来订购模型。

有一个 Doc 模型，它有许多 subcatrels 和 subinsrels，两者都是 Relation 模型（不是模型关系，一个名为“Relation”的模型）。

文档.rb

class Doc < ActiveRecord::Base
  has_many :denotations
  has_many :instances, :through => :denotations
  has_many :subcatrels, :class_name => 'Relation', :through => :denotations, :source => :subrels
  has_many :subinsrels, :class_name => 'Relation', :through => :instances, :source => :subrels
  scope :pmdocs, where(:sourcedb => 'PubMed')
  .
  .
end

我想通过计数 subcatrels 和 subinsrels 的总和来订购 Doc 模型。

我在下面尝试订购范围 pmdocs。

Doc.pmdocs.includes([:subcatrels, :subinsrels]).group('docs.id').order('(count(subcatrels.id) + count(subinsrels.id)) DESC')

并在下面出现错误。

PG::Error: ERROR:  missing FROM-clause entry for table "subcatrels"
LINE 1: SELECT  DISTINCT "docs".id, (count(subcatrels.id) + count(su...

: SELECT  DISTINCT "docs".id, (count(subcatrels.id) + count(subinsrels.id)) AS alias_0 FROM "docs" LEFT OUTER JOIN "denotations" ON "denotations"."doc_id" = "docs"."id" LEFT OUTER JOIN "relations" ON "relations"."subj_id" = "denotations"."id" AND "relations"."subj_type" = 'Denotation' LEFT OUTER JOIN "denotations" "denotations_docs_join" ON "denotations_docs_join"."doc_id" = "docs"."id" LEFT OUTER JOIN "instances" ON "instances"."obj_id" = "denotations_docs_join"."id" LEFT OUTER JOIN "relations" "subinsrels_docs" ON "subinsrels_docs"."subj_id" = "instances"."id" AND "subinsrels_docs"."subj_type" = 'Instance' WHERE "docs"."sourcedb" = 'PubMed' GROUP BY docs.id ORDER BY (count(subcatrels.id) + count(subinsrels.id)) DESC LIMIT 10 OFFSET 0

如何通过计数 subcatrels 和 subinsrels 的总和来订购 Doc 模型？

其他模型源代码如下。

外延.rb

class Denotation < ActiveRecord::Base
  belongs_to :doc
  has_many :instances, :foreign_key => "obj_id", :dependent => :destroy
  has_many :subrels, :class_name => 'Relation', :as => :subj, :dependent => :destroy
  has_many :objrels, :class_name => 'Relation', :as => :obj, :dependent => :destroy
  .
  .
end

实例.rb

class Instance < ActiveRecord::Base
  belongs_to :obj, :class_name => 'Denotation'
  has_many :subrels, :class_name => 'Relation', :as => :subj, :dependent => :destroy
  has_many :objrels, :class_name => 'Relation', :as => :obj, :dependent => :destroy
  .
  .
end

协会形象 在此处输入图像描述

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1 回答 1

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如果不是表名，则不能要求subinsrels.idin WHERE！

于 2013-07-24T11:05:31.367 回答