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POPossible to eager load associations with nested_attributes?
 

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    <p>Just briefly, I have run into a dreaded 2(n) queries problem. If n = the number of skills in the database, then my characters#edit form will take 2(n) queries to load the page. It will SELECT a PlayerSkill (the join table) once every skill, and it will look up the Skill once per skill.</p> <p>Here is some code which I believe is pertinent to the situation. In essence, the models, views, and controllers involved in this process, less the model validations and less the actions I'm not concerned about.</p> <p>The controller:</p> <pre><code> # GET /characters/1/edit def edit @character = Character.find(params[:id], :include =&gt; {:player_skills =&gt; :skill}) stub_player_skills end private def stub_player_skills @skills = Skill.find(:all) @skills.each do |skill| if (skill.player_skills.empty?) ps = @character.player_skills.build(:skill_id =&gt; skill.id, :name =&gt; skill.name) end end end </code></pre> <p>The model(s):</p> <pre><code>class Character &lt; ActiveRecord::Base belongs_to :user belongs_to :campaign has_many :sheets, :dependent =&gt; :destroy has_many :tokens, :dependent =&gt; :destroy has_many :player_skills, :dependent =&gt; :destroy has_many :skills, :through =&gt; :player_skills accepts_nested_attributes_for :player_skills, :allow_destroy =&gt; true end </code></pre> <p>The offending view (HAML):</p> <pre><code>%h1 Editing Character - form_for @character do |f| = f.error_messages %p = f.label :name %br = f.text_field :name %p = f.label :race %br = f.text_field :race %p = f.label :char_class %br = f.text_field :char_class %p -f.fields_for :player_skills do |ps| =ps.object.skill.name =ps.text_field :level =ps.hidden_field :skill_id -unless ps.object.new_record? =ps.check_box '_destroy' =ps.label '_destroy', 'Remove' %br %p = f.submit </code></pre> <p>My understanding of the situation is that eager loading exists to grab the association in (roughly) a single extra query.</p> <p>I need to properly apply eager loading in two areas, and I am just at a loss regarding how to do it.</p> <p>In the stub_player_skills method, it needs to create a PlayerSkill object <em>assuming the character does not already have one.</em> It could benefit from eager loading here because it loops through each skill in the database. This is where the first "n-queries" are coming from.</p> <p>Then on the view, fields_for loops through all the PlayerSkills we've racked up, because there is no way to eager load here, when I call =ps.object.skill.name to print out the skill's name, it does a Skill lookup, which brings in the second set of "n-queries."</p> <p>My primary concern lies in the view layer, I cannot find any documentation (Rails API or otherwise) that states how you could eager load the associations if you're using fields_for to generate a nested form.</p> <p>Thanks for any and all responses :) ~Robbie</p>
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