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PORails - Eager Load Association on an Association
 

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    <p><strong>EDIT - Using 'includes' generates a SQL 'IN' clause. When using Oracle this has a 1,000 item limit. It will not work for my company. Are there any other solutions out there?</strong></p> <p>Is it possible to eager load an association on an association?</p> <p>For example, let's say I have an Academy class, and an academy has many students. Each student belongs_to student_level</p> <pre><code>class Academy &lt; ActiveRecord::Base has_many :students end class Student &lt; ActiveRecord::Base belongs_to :academy belongs_to :student_level end class StudentLevel &lt; ActiveRecord::Base has_many :students end </code></pre> <p>Is it possible to tailor the association in Academy so that when I load the students, I ALWAYS load the student_level with the student?</p> <p>In other words, I would like the following section of code to produce one or two queries total, not one query for every student:</p> <pre><code>@academy.students.each do |student| puts "#{student.name} - #{student.student_level.level_name}" end </code></pre> <p>I know I can do this if I change students from an association to a method, but I don't want to do that as I won't be able to reference students as an association in my other queries. I also know that I can do this in SQL in the following manner, but I want to know if there's a way to do this without finder_sql on my association, because now I need to update my finder_sql anytime my default scope changes, and this won't preload the association:</p> <pre><code>SELECT students.*, student_levels.* FROM students LEFT JOIN student_levels ON students.student_level_id = student_levels.id WHERE students.academy_id = ACADEMY_ID_HERE </code></pre>
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