has_many :through无法加载记录

Question

我是一名有用的助手，可以为您进行翻译。以下是需要翻译的内容：

我有一个Rails 5.2.1应用程序，其中每个关系的每个步骤都有效，但has_many:through版本无效。设置有点奇怪，但我觉得我已经正确设置了所有内容，所以我有点困惑。

鉴于这段代码：

class Contact < SalesforceModel
  self.table_name =  'salesforce.contact'
  self.primary_key = 'sfid'

  has_many :content_accesses, foreign_key: 'contact__c', class_name: 'ContentAccess'
  has_many :concepts, through: :content_accesses, source: :inventory
end

class ContentAccess < ApplicationRecord
  self.table_name =  'salesforce.content_access__c'
  self.primary_key = 'sfid'

  belongs_to :inventory, foreign_key: 'inventory__c', inverse_of: :content_accesses, primary_key: 'sfid', class_name: 'Inventory'
  belongs_to :contact, foreign_key: 'contact__c', inverse_of: : content_accesses, primary_key: 'sfid', class_name: 'Contact'
end

class Inventory < SalesforceModel
  self.table_name = 'salesforce.inventory__c'
  self.primary_key = 'sfid'

  has_many :content_accesses, foreign_key: 'inventory__c'
  has_many :contacts, through: :content_accesses
end

每个 has_many :through 步骤都起到了作用：

# Setup
2.5.1 :001 > contact = Contact.first
  Contact Load (30.6ms)  SELECT  "salesforce"."contact".* FROM "salesforce"."contact" ORDER BY "salesforce"."contact"."sfid" ASC LIMIT $1  [["LIMIT", 1]]
 => #<Contact lastname: "Doe", mailingpostalcode: "90210", name: "John Doe", mobilephone: nil, birthdate: nil, phone: nil, mailingstreet: "123 ABC Street", isdeleted: false, systemmodstamp: "2018-03-16 00:09:01", mailingstatecode: "CA", createddate: "2018-03-15 17:50:44", mailingcity: "LA", mailingcountrycode: "US", firstname: "John", email: "[e-mail]", sfid: "003m000000txXhwAAE", id: "003m000000txXhwAAE", _hc_lastop: "SYNCED", _hc_err: nil> 

# Accessing related ContentAccess works
2.5.1 :002 > contact.content_accesses.count
   (2.0ms)  SELECT COUNT(*) FROM "salesforce"."content_access__c" WHERE "salesforce"."content_access__c"."contact__c" = $1  [["contact__c", "003m000000txXhwAAE"]]
 => 2 

# Accessing related Inventory, through the related ContentAccess works
2.5.1 :003 > contact.content_accesses.first.inventory  
  ContentAccess Load (0.6ms)  SELECT  "salesforce"."content_access__c".* FROM "salesforce"."content_access__c" WHERE "salesforce"."content_access__c"."contact__c" = $1 ORDER BY "salesforce"."content_access__c"."sfid" ASC LIMIT $2  [["contact__c", "003m000000txXhwAAE"], ["LIMIT", 1]]
  Inventory Load (30.4ms)  SELECT  "salesforce"."inventory__c".* FROM "salesforce"."inventory__c" WHERE "salesforce"."inventory__c"."sfid" = $1 LIMIT $2  [["sfid", "a1mm0000001S9qzAAC"], ["LIMIT", 1]]
 => #<Inventory createddate: "2018-05-23 15:09:41", isdeleted: false, name: "Some Concept Name", systemmodstamp: "2018-05-23 15:09:42", sfid: "a1mm0000001S9qzAAC", id: "a1mm0000001S9qzAAC", _hc_lastop: "SYNCED", _hc_err: nil> 

# Accessing the related inventory through the has_many :through does not work
2.5.1 :004 > contact.concepts.count
   (33.0ms)  SELECT COUNT(*) FROM "salesforce"."inventory__c" INNER JOIN "salesforce"."content_access__c" ON "salesforce"."inventory__c"."sfid" = "salesforce"."content_access__c"."inventory__c" WHERE "salesforce"."content_access__c"."contact__c" = $1  [["contact__c", "003m000000txXhwAAE"]]
 => 0 

在Postgres中运行生成的查询是有效的：

app_development=# SELECT COUNT(*) FROM "salesforce"."inventory__c" INNER JOIN "salesforce"."content_access__c" ON "salesforce"."inventory__c"."sfid" = "salesforce"."content_access__c"."inventory__c" WHERE "salesforce"."content_access__c"."contact__c" = '003m000000txXhwAAE';
 count 
-------
     2
(1 row)

运行 Contact.first.concepts.to_sql 会产生以下结果：

SELECT "salesforce"."inventory__c".* FROM "salesforce"."inventory__c" INNER JOIN "salesforce"."content_access__c" ON "salesforce"."inventory__c"."sfid" = "salesforce"."content_access__c"."inventory__c" WHERE "salesforce"."content_access__c"."contact__c" = '003m000000txXhwAAE'

将该查询通过psql运行正常，从inventory__c表返回正确的记录。

反向操作也存在相同的问题：

2.5.1 :002 > inventory = Inventory.first
  Inventory Load (30.2ms)  SELECT  "salesforce"."inventory__c".* FROM "salesforce"."inventory__c" ORDER BY "salesforce"."inventory__c"."sfid" ASC LIMIT $1  [["LIMIT", 1]]
 => #<Inventory createddate: "2018-05-23 15:09:41", isdeleted: false, name: "Positive Focus", systemmodstamp: "2018-05-23 15:09:42", inventory_unique_name__c: "Inventory 1", sfid: "a1mm0000001S9qzAAC", id: "a1mm0000001S9qzAAC", _hc_lastop: "SYNCED", _hc_err: nil> 
2.5.1 :003 > inventory.content_accesses.first.contact
  ContentAccess Load (0.9ms)  SELECT  "salesforce"."content_access__c".* FROM "salesforce"."content_access__c" WHERE "salesforce"."content_access__c"."inventory__c" = $1 ORDER BY "salesforce"."content_access__c"."sfid" ASC LIMIT $2  [["inventory__c", "a1mm0000001S9qzAAC"], ["LIMIT", 1]]
  Contact Load (30.9ms)  SELECT  "salesforce"."contact".* FROM "salesforce"."contact" WHERE "salesforce"."contact"."sfid" = $1 LIMIT $2  [["sfid", "003m000000txXhwAAE"], ["LIMIT", 1]]
 => #<Contact sfid: "003m000000txXhwAAE", id: "003m000000txXhwAAE", [...etc...] > 
2.5.1 :004 > inventory.contacts.count
   (30.7ms)  SELECT COUNT(*) FROM "salesforce"."contact" INNER JOIN "salesforce"."content_access__c" ON "salesforce"."contact"."sfid" = "salesforce"."content_access__c"."contact__c" WHERE "salesforce"."content_access__c"."inventory__c" = $1  [["inventory__c", "a1mm0000001S9qzAAC"]]
 => 0 

所以：一切似乎都正确连接了，那么为什么直通版本没有工作呢？任何帮助将不胜感激。

谢谢！❤️

- Tim Sullivan

---

@bkimble source 是 :inventory，因为它是通过 content_accesses 关系的源。concepts 可以访问 inventory 对象。请参阅：https://dev59.com/6m445IYBdhLWcg3w6ebz - Tim Sullivan

@Pablo 你说得对！这并没有解决问题，但是这是我犯的一个愚蠢的错误。我会更新问题。 - Tim Sullivan

尝试运行 contact.concepts.to_sql 并将结果添加到问题中。 - xploshioOn

@xploshioOn 当然可以！我已经通过联系人的概念更新了这个问题.to_sql。 - Tim Sullivan

你的SalesforceModel里有什么？ - Zabba

Answer 1

感谢@Zabba的评论，提出了关于SalesforceModel的问题，我得以找到问题所在。根本上讲，问题是这样的：

class ContentAccess < ApplicationRecord

应该是这样的：

class ContentAccess < SalesforceModel # <-- it was using the wrong table, effectively.

这是一个令人疲惫的一周，但现在情况已经好转了。

- Tim Sullivan