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PORuby on Rails: many-to-many relationship
 

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  1. PORuby on Rails: many-to-many relationship
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    <p>I have a database with 3 tables: User, Card, Cardset:</p> <pre><code>User has_many Cards User has_many Cardsets Card belongs_to User Cardset belongs_to User Card has_and_belongs_to_many Cardsets Cardset has_and_belongs_to_many Cards </code></pre> <p>A card is basically a "flashcard", it has card.term and card.definition columns.</p> <p>In the view card/new.html, in which the logged in user can create new cards, I created the following form:</p> <pre><code>&lt;%= form_for(@card) do |f| %&gt; &lt;%= f.label :term, "Termin" %&gt; &lt;%= f.text_field :term %&gt; &lt;%= f.label :definition, "Definicja" %&gt; &lt;%= f.text_area :definition %&gt; &lt;%= f.label :cardset, "Dodaj automatycznie do setu:" %&gt; &lt;%= select("cardset", :id, current_user.cardsets.all.collect {|p| [ p.name, p.id ] }, {:include_blank =&gt; true}) %&gt; &lt;br&gt; &lt;%= f.submit "Dodaj kartę!", class: "btn btn-large btn-primary" %&gt; &lt;% end %&gt; </code></pre> <p>The problematic line is this:</p> <pre><code>&lt;%= select("cardset", :id, current_user.cardsets.all.collect {|p| [ p.name, p.id ] }, {:include_blank =&gt; true}) %&gt; </code></pre> <p>I want this to be a drop down menu containing all the sets that belong to the user who is creating the new card. When users chooses a set from this list and clicks submit, the relation (a many-to-many relation, in table: Cards_Cardsets) between the new card and the chosen cardset is automatically created.</p> <p>In my card_controller I have:</p> <pre><code>def create @card = current_user.cards.build(params[:card]) @cardset = Cardset.find_by_id(params[:cardset]) @card.cardsets&lt;&lt;@cardset if @card.save flash[:success] = "Utworzono karte!" render 'show' else flash.now[:error] = 'Uzupelnij pola.' render 'new' end end </code></pre> <p>The line:</p> <pre><code>@cardset = Cardset.find_by_id(params[:cardset]) </code></pre> <p>is suposed to return the chosen cardset. But instead, it returns this error:</p> <pre><code>Unknown key: id app/controllers/cards_controller.rb:8:in 'create' </code></pre> <p>if I hardcode the id into this line like this:</p> <pre><code>@cardset = Cardset.find_by_id(3) </code></pre> <p>it then works. So i guess the problem is caused by this expression:</p> <pre><code>params[:cardset] </code></pre> <p>How can I get it to work?</p>
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    1. PTQuestion
    1. USSergio Tulentsev
    1. USNatalia Zoń
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      1. PORuby on Rails: many-to-many relationship
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      1. VTUpMod
    1. COwhat error is returned?
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      1. PORuby on Rails: many-to-many relationship
      1. USJonathan
    2. COSorry, I hadn't paste the whole post. Now it's as it should have been.
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      1. PORuby on Rails: many-to-many relationship
      1. USNatalia Zoń
    3. COwhat is the output of `puts params.inspect` ?
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      1. PORuby on Rails: many-to-many relationship
      1. USJonathan
 

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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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