ruby on rails - Best way to get a list of parent IDs -

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मेरे रेल एप्लिकेशन में इन मॉडलों हैं: 

  वर्ग कोर्स & lt; ActiveRecord :: बेस has_many: विषयों के अंत वर्ग विषय & lt; ActiveRecord :: बेस है has_many: भागों belong_to: पाठ्यक्रम अंत वर्ग भाग & lt; ActiveRecord :: बेस has_many: क्विज़ संबंधित_तो: विषय के अंत वर्ग प्रश्नोत्तरी & lt; ActiveRecord :: बेस has_many: quiz_submissions belong_to: भाग अंत वर्ग QuizSubmission & lt; ActiveRecord :: बेस is_to: quiz end

अब मुझे सभी क्विज़शूमिशन कोर्स आईडी प्राप्त करना है, अर्थात quiz_submission.quiz.part.topic.course.id के लिए प्रत्येक क्विज_समिशन।

मेरा वर्तमान कोड है QuizSubmission.all.map {| qs | Qs.quiz.part.topic.cours.id} जो बेहद धीमी है, मैंने भी शामिल होने की कोशिश की है , फिर भी प्रदर्शन में सुधार नहीं हुआ है शायद मैंने शामिल हो गलत तरीके से उपयोग किया।

कोई सुझाव? क्या मुझे प्रश्नोत्तरी सबमिट करना चाहिए: पाठ्यक्रम ? धन्यवाद!

आप ऐसा कर सकते हैं: 

  QuizSubmission.joins (: प्रश्नोत्तरी = & gt; {: भाग = & gt; {: topic = & gt;: कोर्स}})। चयन करें ('quiz_submissions.id, course_id as course_id')

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