Has_and_belongs_to_many - help?

I know it has been asked many times, but i could not find any working
examples even after 2 days for googling. So, i thought let me ask here.
How do I save in HABTM

Its a simple application where users should be able to post recipes and
that recipe HABTM categories. Multiple categories are selected through
multi select list box.

  1. I have 2 models: Recipe and Category
  2. I have one join table: categories_recipes (category_id, recipe_id)

Now this is in my controller:

class RecipesController < ApplicationController
def new
@recipe = Recipe.new
@categories = Category.find(:all)
end

def create
@recipe = Recipe.new(params[:recipe])
@recipe.category_recipe_ids[]<<(params[:category_recipe_ids])
@recipe.save
redirect_to :action=>‘show’, :id=>@recipe.id
end

def show
@recipe=Recipe.find(params[:id])
end
end

My new.html.erb

<% form_for :recipe, @recipe, :url => { :action => “create” } do |f| %>
<%= f.text_field :title, :maxlength => 100 %>

<%= f.text_area :description, :rows=>‘xx’, :cols=>‘yy’ %>

<%= select_tag ‘category_recipe_ids[]’,
options_from_collection_for_select(@categories, :id, :title), {
:multiple => true, :size =>5, :id => “categories_recipes_id” } %>


<%= submit_tag ‘save’,
:style=>‘font-size:14px;font-weight:bold;width:100px’ %>

<% end %>

Any help is much appreciated.

I’m new to rails and will be interested how this works out, so I’ll be
watching this thread.

What errors are you getting?

On Wed, Jul 15, 2009 at 6:12 AM, Rails L. <
[email protected]> wrote:

  1. I have one join table: categories_recipes (category_id, recipe_id)
    @recipe = Recipe.new(params[:recipe])
    My new.html.erb

Any help is much appreciated.

Posted via http://www.ruby-forum.com/.


Rick R

Could you also paste your models and migrations?

On Wed, Jul 15, 2009 at 3:30 PM, Rick [email protected] wrote:

I know it has been asked many times, but i could not find any working
Now this is in my controller:
@recipe.save
<% form_for :recipe, @recipe, :url => { :action => “create” } do |f| %>

Posted via http://www.ruby-forum.com/.


Rick R


Rick R

Have you looked this tutorial
http://www.buildingwebapps.com/podcasts/6789-resources-page-links-categories-and-habtm/show_notes(download
the second link source code.)

Again, I’m new, so take this for what its worth…

Notice in their create method for pages and links (the two that have the
habtm relationship) there is no need to add the collection to the main
object. It looks like you shouldn’t need:

@recipe.category_recipe_ids[]<<(params[:category_recipe_ids])

You should just be able to use

@recipe = Recipe.new

And it should pull in the selected categories from your select options.

Not sure if it matters but in the example posted they are using a
different
select tag than you’re using:

<%= f.collection_select :category_ids, Category.find(:all, :order =>
‘title’), :id, :title, {}, :multiple => true %>

Actually looking at your select tag I’m not sure how something like
“recipe_ids” would be set the way you have it:

<%= select_tag ‘category_recipe_ids[]’,
options_from_collection_for_select(@categories, :id, :title), {
:multiple => true, :size =>5, :id => “categories_recipes_id” }
%>
Why not try something like have shown:

<%= f.collection_select :category_ids, Recipe.find(:all), :id, :title,
{},
:multiple => true %>

Also if you were going to be setting the categories in recipes (which I
don’t think you need to do anyway), wouldn’t it be something like

@recipe.category_ids <<(params[:category_ids])

I don’t think you’d set the category_recipe_id ? (Again, I’m new so I
could
be way off here.)

On Wed, Jul 15, 2009 at 6:12 AM, Rails L. <
[email protected]> wrote:

  1. I have one join table: categories_recipes (category_id, recipe_id)
    @recipe = Recipe.new(params[:recipe])
    My new.html.erb

Any help is much appreciated.

Posted via http://www.ruby-forum.com/.


Rick R

Forgot to include the joining table which is

categories_recipes(category_id, recipe_id)

You will have to create this table manually without id column.

Riiiick, you are a star. Atlast we have a working example for HABTM. I
have given here the complete code if anyone needs it.

Problem: A recipe can have many categories and a Category can have many
recipes.

Model: Recipe

class Recipe < ActiveRecord::Base
has_and_belongs_to_many :categories
end

Model: Category

class Category < ActiveRecord::Base
has_and_belongs_to_many :recipes
end

Controller: recipes_controller

class RecipesController < ApplicationController
def new
@recipe = Recipe.new
@categories = Category.find(:all)
end

def create
@recipe = Recipe.new(params[:recipe])
@recipe.save
redirect_to :action=>‘show’, :id=>@recipe.id
end

def show
@recipe=Recipe.find(params[:id])
end
end

View: New.html.erb

<% form_for :recipe, @recipe, :url => { :action => “create” } do |f| %>
<%= f.text_field :title, :maxlength => 100 %>
<%= f.collection_select :category_ids, @categories, :id, :title, {},
:multiple => true %>
<%= submit_tag ‘save’,
:style=>‘font-size:14px;font-weight:bold;width:100px’ %>

<% end %>

View: Show.html.erb

<%= @recipe.title %>
<% @recipe.categories.each do |c|%>
<%= c.title %>
<% end %>

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