Activerecord加入不返回所有預期的結果

我有一個預先存在的postgres數據庫，我試圖查詢。我已經建立了兩個模型，客戶和設備。我試圖查詢兩個表與一個非標準的密鑰加入他們。無論我嘗試了什麼，我只能從一張桌子上得到結果。我試着改變ActiveRecord行爲來使用非標準鍵以及find_by_sql（）。由於現有的表結構，我也禁用了默認表複數。我錯過了明顯的東西嗎？Activerecord加入不返回所有預期的結果

ActiveRecord::Base.pluralize_table_names = false 

    class Customer < ActiveRecord::Base 
     self.primary_key = :acct 
     has_many :equipment, foreign_key: 'acct' 
    end 

    class Equipment < ActiveRecord::Base 
     self.primary_key = :acct 
     belongs_to :customer, foreign_key: 'acct' 
    end 

    [email protected]:~/rails_workspace/pg_test$ rails c 
    Loading development environment (Rails 4.2.0.rc2) 
    2.2.1 :001 > Customer.first() 
     Customer Load (16.9ms) SELECT "customer".* FROM "customer" ORDER BY "customer"."acct" ASC LIMIT 1 
    => #<Customer acct: "000002", franchise: "501", name: "NAME", address: "STREET ADDR", city: "CITY", state: "ST", zip: "ZIPCODE", phone: "1234567890", email: "[email protected]", installdate: "2014-02-20", consumptiondate: nil, parent: "", sentoverage: false, exempt: false, pin: "", locked: false, status: "ACT"> 
    2.2.1 :002 > Equipment.first() 
     Equipment Load (128.3ms) SELECT "equipment".* FROM "equipment" ORDER BY "equipment"."acct" ASC LIMIT 1 
    => #<Equipment mac: "26225070", acct: "000002"> 
    2.2.1 :003 > 


    2.2.1 :009 > Customer.find_by_sql("Select c.*, e.* from customer as c, equipment as e where e.acct = c.acct and c.acct = '000002' limit 1") 

    Customer Load (53.9ms) Select c.*, e.* from customer as c, equipment as e where e.acct = c.acct and c.acct = '000002' limit 1 
    => [#<Customer acct: "000002", franchise: "501", name: "NAME", address: "STREET ADDR", city: "CITY", state: "ST", zip: "ZIPCODE", phone: "1234567890", email: "[email protected]", installdate: "2014-02-20", consumptiondate: nil, parent: "", sentoverage: false, exempt: false, pin: "", locked: false, status: "ACT">] 

    2.2.1 :010 > Customer.joins('FULL OUTER JOIN equipment ON equipment.acct = customer.acct').limit(1) 
     Customer Load (119.9ms) SELECT "customer".* FROM "customer" FULL OUTER JOIN equipment ON equipment.acct = customer.acct LIMIT 1 
    => #<ActiveRecord::Relation [#<Customer acct: "000002", franchise: "501", name: "NAME", address: "STREET ADDR", city: "CITY", state: "ST", zip: "ZIPCODE", phone: "1234567890", email: "[email protected]", installdate: "2014-02-20", consumptiondate: nil, parent: "", sentoverage: false, exempt: false, pin: "", locked: false, status: "ACT">]> 

    2.2.1 :011 > Customer.joins(:equipment) 
    ActiveRecord::ConfigurationError: Association named 'equipment' was not found on Customer; perhaps you misspelled it? 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/associations/join_dependency.rb:218:in `find_reflection' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/associations/join_dependency.rb:223:in `block in build' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/associations/join_dependency.rb:222:in `each' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/associations/join_dependency.rb:222:in `map' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/associations/join_dependency.rb:222:in `build' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/associations/join_dependency.rb:99:in `initialize' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation/query_methods.rb:1039:in `new' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation/query_methods.rb:1039:in `build_joins' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation/query_methods.rb:863:in `build_arel' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation/query_methods.rb:855:in `arel' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation.rb:638:in `exec_queries' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation.rb:514:in `load' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation.rb:243:in `to_a' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activerecord-4.2.0.rc2/lib/active_record/relation.rb:629:in `inspect' 
    from /home/me/.rvm/gems/[email protected]_test/gems/railties-4.2.0.rc2/lib/rails/commands/console.rb:110:in `start' 
    from /home/me/.rvm/gems/[email protected]_test/gems/railties-4.2.0.rc2/lib/rails/commands/console.rb:9:in `start' 
    from /home/me/.rvm/gems/[email protected]_test/gems/railties-4.2.0.rc2/lib/rails/commands/commands_tasks.rb:68:in `console' 
    from /home/me/.rvm/gems/[email protected]_test/gems/railties-4.2.0.rc2/lib/rails/commands/commands_tasks.rb:39:in `run_command!' 
    from /home/me/.rvm/gems/[email protected]_test/gems/railties-4.2.0.rc2/lib/rails/commands.rb:17:in `<top (required)>' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:274:in `require' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:274:in `block in require' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:240:in `load_dependency' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:274:in `require' 
    from /home/me/rails_workspace/pg_test/bin/rails:8:in `<top (required)>' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:268:in `load' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:268:in `block in load' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:240:in `load_dependency' 
    from /home/me/.rvm/gems/[email protected]_test/gems/activesupport-4.2.0.rc2/lib/active_support/dependencies.rb:268:in `load' 
    from /home/me/.rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require' 
    from /home/me/.rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require' 
    from -e:1:in `<main>'2.2.1 :012 >

編輯

改性的設備類改變belongs_to的：設備到：設備。導致修復ActiveRecord :: ConfigurationError：關聯名爲'設備'錯誤。但仍然沒有解決的加入。如果我使用Customer表中的「key」手動查詢Equipment表，則會找到數據記錄。

2.2.1 :008 > Customer.joins(:equipment).limit(1) 
    Customer Load (11.9ms) SELECT "customer".* FROM "customer" INNER JOIN "equipment" ON "equipment"."acct" = "customer"."acct" LIMIT 1 
=> #<ActiveRecord::Relation > [#<Customer acct: "000002", franchise: "501", name: "NAME", address: "STREET ADDR", city: "CITY", state: "ST", zip: "ZIPCODE", phone: "1234567890", email: "[email protected]", installdate: "2014-02-20", consumptiondate: nil, parent: "", sentoverage: false, exempt: false, pin: "", locked: false, status: "ACT">] 

2.2.1 :017 > Equipment.where(acct: '000002') 
    Equipment Load (76.5ms) SELECT "equipment".* FROM "equipment" WHERE "equipment"."acct" = $1 [["acct", "000002"]] 
=> #<ActiveRecord::Relation [#<Equipment mac: "26225070", acct: "000002">, #<Equipment mac: "23126536", acct: "000002">, #<Equipment mac: "00E06F76A08A", acct: "000002">]>

來源

2015-03-13 hackerkatt

它可能與你聲明的關係的方式。你應該只有一個'belongs_to'（帶有外鍵列的類）。另一個類應該有'has_one'或'has_many'。請參閱我的複製/粘貼中的http://guides.rubyonrails.org/association_basics.html – Baldrick 2015-03-13 18:47:16

錯字。更新帖子 – hackerkatt 2015-03-13 18:56:53

現在連接有什麼問題？ 'Customer.joins（：equipment）.limit（1）'的輸出對我來說不一定是錯誤的。我錯過了什麼？也許你期望'Customer.joins'返回一個'Equipment'，但你需要做'Equipment.joins（：customer）'來做到這一點。 – 2015-03-13 19:42:48

對於一個簡單的解決方案scopeby_customer在Equipment模型定義，

class Equipment < ActiveRecord::Base 
    ... 
    scope :by_customer,->(customer_conditions) { joins(:customer).where(customer: customer_conditions)}  
end

，並按照Customer模型scopeby_equipment，

class Customer < ActiveRecord::Base 
    ... 
    scope :by_equipment,->(equipment_conditions) { joins(:equipment).where(equipment: equipment_conditions)} 
end

To find Equipments of Customer '000002'

@equipments = Equipment.by_customer(acct: '000002')

To find Customer who has an equipment of mac address is '26225070'

@customer = Customer.by_equipment(mac: '26225070')

來源

2015-03-13 20:38:16

我想我可能會看到你錯過了什麼。

Customer.joins(:anything)將返回Customer的集合。

Equipment.joins(:anything)將返回Equipment的集合。

也許你已經明白，但也許不是。

如果你想要一個結果集是兩者的結合，我想你必須完全從另一個角度來看它，而且我認爲我需要更好地理解你最終的結果之後才能提供任何好的建議。

編輯：拿裝備屬於特定客戶：

Equipment.joins(:customer).where('customer.acct = ?', '000002')

要獲得客戶對設備mac：

Customer.joins(:equipment).where('equipment.mac = ?', '26225070')

來源

2015-03-13 19:46:15

真的在尋找簡單的東西。我想要一個查詢返回屬於客戶的所有設備。通常會通過篩選特定鍵的條件。還希望能夠做一個反向查詢...返回客戶記錄具有acct = x從設備表有mac = x – hackerkatt 2015-03-13 20:04:05

好吧，我想我明白了。看到我更新的答案。 – 2015-03-13 20:10:12

謝謝傑森！ Shavvy的回答也是一個解決方案。他需要爲模型添加範圍。我想更好地理解爲什麼我的查詢沒有返回一個集合，因爲這裏做的唯一事情是在mac或acct上傳遞一個條件過濾器。 – hackerkatt 2015-03-14 00:22:45

Activerecord加入不返回所有預期的結果

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