Using group_by in a Rails view

rubyonrails-talk
1

Walter,

Thanks for your reply.

I am going for a display like the following:

Fruit Apple Orange Peach Meat Beef Fish Poultry

Fruit and Meat are category names and apple, orange, peach, etc are type names.

This information is being stored in a join table that look like the following:

post_id keyword_category_id keyword_type_id 1 1 1 1 1 2
1 1 3

The schema look like the following:

keywords table id :integer post_id: integer keyword_category_id :integer keyword_type_id :integer

keyword_categories table id :integer name: string

keyword_types table id: integer name: string keyword_category_id :integer

I thought I could do the following: . <% @post.keywords.group_by(&:keyword_category).each do |category, type| %>

  • <%= category.keyword_category.name %>
    • <% type.each do |type| %> <%= type.keyword_type.name %> <% end %> <% end %>

    This code doesn’t work.

    I had to use &:keyword_category_id as in the code below. The output look like

    1 1 2 3 2 4 5 6

    I want to display the category names and type names instead of the foreign key ids. I think I am using group_by wrong or even perhaps i need an association in the other direction. I am just baffled at the moment.

    Any ideas?

    2

    Walter,

    Thanks for your reply.

    I am going for a display like the following:

    Fruit   Apple   Orange    Peach Meat   Beef   Fish   Poultry

    Fruit and Meat are category names and apple, orange, peach, etc are type names.

    This information is being stored in a join table that look like the following:

    post_id keyword_category_id keyword_type_id 1 1 1 1 1 2
    1 1 3

    The schema look like the following:

    keywords table id :integer post_id: integer keyword_category_id :integer keyword_type_id :integer

    keyword_categories table id :integer name: string

    keyword_types table id: integer name: string keyword_category_id :integer

    I thought I could do the following: . <% @post.keywords.group_by(&:keyword_category).each do |category, type| %>   <li><%= category.keyword_category.name %></li>     <% type.each do |type| %>   <%= type.keyword_type.name %>   <% end %> <% end %> This code doesn't work.

    I had to use &:keyword_category_id as in the code below. The output look like

    1    1    2    3 2    4    5    6     I want to display the category names and type names instead of the foreign key ids. I think I am using group_by wrong or even perhaps i need an association in the other direction. I am just baffled at the moment.

    Any ideas?

    You might want to look at this blog post (kind of old, but it might help): Rails: Group results by week (using group_by) · devroom.io

    You might also want to read through the Rails Guide on Associations, and see if you can parse out what's missing in your relationships. Make sure that each has_many is balanced on the other side by a belongs_to.

    Walter