I followed several tutorial to make this work, but I can't get draggable items.
Here's what i did:
added gem 'acts_as_list' in my GemFile and did a bundle install
added <%= javascript_include_tag :defaults %> to my application.html.erb
added an :integer column named position to my facilities;
added acts_as_list in my facility model;
added the sort method in my facility model:
def sort
#facilities = Facility.all
#facilities.each do |f|
f.position = params['f'].index(f.id.to_s) + 1
f.save
end
end
added this in my view:
<ul id="facilities">
<% for facility in Facility.all %>
<% content_tag_for :li, facility do %>
<span class="handle">[drag]</span>
<%= link_to h(facility.name), facility %>
<% end %>
<% end %>
</ul>
<%= sortable_element("facilities", :url => sort_facilities_path, :handle => "handle") %>
added this to the routes:
resources :facilities do
collection do
post :sort
end
end
But in the end i have only a normal list, not draggable!
What am i missing?
Thanks!
As far as I remember does acts_as_list only deal with lists in Rails' models which means the server side of things. In order to make a list element draggable you'll have to include a client side library or plugin such as jQuery UI. The gem itself doesn't (or at least didn't use to) include the functionality you're describing.
This library or solution will then
make your elements draggable and
provide you with a callback to update the order in the DB (usually using an AJAX call)
Related
I have a model called Language, with just two columns: language and link, and would like to be able to loop through each link for each language and display in the view. i.e. (obviously this isn't code, it's just to illustrate the desired pattern)
Language 1
Link 1
Link 2
Link 3
Language 2
Link 1
Language 3
Link 1
Link 2
Language 4
etc
What is the 'rails way' of extracting this data, and then presenting in the view? (note: I would know how to do this easily if the data were in two different models, but it isn't)
So, a Railsy way would be to use the following in your controller:
#languages = Language.all.group_by(&:language)
This will give you a hash of languages grouped by the (erm...) language's language (<- perhaps rename the column to name to avoid this ambiguity?):
# { 'English' => [language_1, language_2, etc...],
# 'French' => [language_3, language_4],
# etc... }
And then this in your view:
<% #languages.each do |language_name, languages| %>
<h1>
<%= language_name %>
</h1>
<% languages.each do |language| %>
<p>
<%= language.link %>
</p>
<% end %>
<% end %>
Obviously the HTML tags can be whatever you'd like, though I hope that gives a useful example.
However, there's a caveat here - as your database grows, this might not prove an efficient way of working. You'll likely be better off setting up a separate model for links, with a one-to-many relationship between languages and links.
For example:
# langage.rb
has_many :links
# link.rb
belongs_to :language
# your controller
#languages = Language.includes(:links)
And then something like the following in the view:
<% #languages.each do |language| %>
<h1>
<%= language.language %>
</h1>
<% language.links.each do |link| %>
<p>
<%= link.url %>
</p>
<% end %>
<% end %>
I'm creating a application using ruby on rails, but currently i'm suffering a problem like db relation, below my code:
Company
has_many :posts, :foreign_key => :company_id
Post
belongs_to :companies, :foreign_key => :company_id
controller
#post = current_user.companies.all
view
<% #post.each do |p| %>
<%= p.posts.post_title %>
<% end %>
Showing error above code.
If I debug like use <%= debug p.posts %> then showing all posts, which is under my companies but when I use <%= debug p.posts.post_title %> then showing ActiveRecord_Associations_CollectionProxy:0x0000000e490b98
Thanks
I think the problem here is that you are trying to call the method :post_title on p.posts, which is an ActiveRecord::Associations::CollectionProxy object.
In your example, p is a Company object, which has a method posts, which returns to you a CollectionProxy object that acts a lot like a list of posts. That list will not have a method post_title, but each element of that list will have a method post_title
So, instead of
<% #post.each do |p| %>
<%= p.posts.post_title %>
<% end %>
You will want something like:
<% #post.each do |company| %>
<% company.posts.each do |post| %>
<%= post.post_title %>
<% end %>
<% end %>
Two additional things to note:
1) The variable #post is inaccurately named. Inaccurate variable names will lead to confusion when trying to understand what is happening. current_user.companies.all returns a list of companies, and therefore, it should read:
#companies = current_user.companies.all
not
#post = current_user.companies.all
2) The actual error that is being shown to you likely says something like
Undefined Method 'post_title' for ActiveRecord_Associations_CollectionProxy:0x0000000e490b98
Not just
ActiveRecord_Associations_CollectionProxy:0x0000000e490b98
When debugging and asking for help, it's very important to note the entire message of the exception being raised.
Because companiy has_many :posts........ posts are objects you need a loop to show all posts e.g
p.posts.each do |post|
Let's say I have a comment model:
class Comment < ActiveRecord::Base
has_many :replies, class: "Comment", foreign_key: "reply_id"
end
I can show a comment instance`s replies in a view like so:
comment.replies do |reply|
reply.content
end
However, how do I loop through the replies of the reply? And its reply? And its reply ad infitum? I'm feeling we need to make a multidimensional array of the replies via class method and then loop through this array in the view.
I don't want to use a gem, I want to learn
It seems like what you have is one short step away from what you want. You just need to use recursion to call the same code for each reply as you're calling for the original comments. E.g.
<!-- view -->
<div id="comments">
<%= render partial: "comment", collection: #comments %>
</div>
<!-- _comment partial -->
<div class="comment">
<p><%= comment.content %></p>
<%= render partial: "comment", collection: comment.replies %>
</div>
NB: this isn't the most efficient way of doing things. Each time you call comment.replies active record will run another database query. There's definitely room for improvement but that's the basic idea anyway.
Would using a nested set still count as 'from scratch'?
The short description of a nested set is a database-specific strategy of querying hierarchies by storing/querying pre- and post-order tree traversal counts.
A picture is worth a thousand words (see also, the wikipedia page on nested sets).
There are a bunch of nested set gems, and I can personally speak for the quality of Awesome Nested Set and Ancestry
Then, Awesome Nested Set (I know from experience, presumably Ancestry too) provide helpers to do a single query to pull up all records under a tree, and iterate through the tree in sorted depth-first order, passing in the level while you go.
The view code for Awesome Nested Set would be something like:
<% Comment.each_with_level(#post.comments.self_and_descendants) do |comment, level| %>
<div style="margin-left: <%= level * 50 %>px">
<%= comment.body %>
<%# etc %>
</div>
<% end %>
I just made that up from vague memories, and it's been a while, so this is where it can be "an exercise for the reader"
My approach is to make this done as efficient as possible.
First lets address how to do that:
DRY solution.
Least Number of queries to retrieve the comments.
Thinking about that, I have found that most of the people address the first but not the second.So lets start with the easy one.
we have to have partial for the comments so referencing the answer of jeanaux
we can use his approach to display the comments and will update it later in the answer
<!-- view -->
<div id="comments">
<%= render partial: "comment", collection: #comments %>
</div>
<!-- _comment partial -->
<div class="comment">
<p><%= comment.content %></p>
<%= render partial: "comment", collection: comment.replies %>
</div>
We must now retrieve those comments in one query if possible so we can just do this in the controller. to be able to do this all comments and replies should have a commentable_id (and type if polymorphic) so that when we query we can get all comments then group them the way we want.
So if we have a post for example and we want to get all its comments we will say in the controller.
#comments = #post.comments.group_by {|c| c.reply_id}
by this we have comments in one query processed to be displayed directly
Now we can do this to display them instead of what we previously did
All the comments that are not replies are now in the #comments[nil] as they had no reply_id
(NB: I don like the #comments[nil] if anyone has any other suggestion please comment or edit)
<!-- view -->
<div id="comments">
<%= render partial: "comment", collection: #comments[nil] %>
</div>
All the replies for each comment will be in the has under the parent comment id
<!-- _comment partial -->
<div class="comment">
<p><%= comment.content %></p>
<%= render partial: "comment", collection: #comments[comment.id] %>
</div>
To wrap up:
We added an object_id in the comment model to be able to retrieve
them( if not already there)
We added grouping by reply_id to
retrieve the comments with one query and process them for the view.
We added a partial that recursively displays the comments (as
proposed by jeanaux).
It seems like you need a self-referential association. Check out the following railscast: http://railscasts.com/episodes/163-self-referential-association
We've done this:
We used the ancestry gem to create a hierarchy-centric dataset, and then outputted with a partial outputting an ordered list:
#app/views/categories/index.html.erb
<% # collection = ancestry object %>
<%= render partial: "category", locals: { collection: collection } %>
#app/views/categories/_category.html.erb
<ol class="categories">
<% collection.arrange.each do |category, sub_item| %>
<li>
<!-- Category -->
<div class="category">
<%= link_to category.title, edit_admin_category_path(category) %>
<%= link_to "+", admin_category_new_path(category), title: "New Categorgy", data: {placement: "bottom"} %>
<% if category.prime? %>
<%= link_to "", admin_category_path(category), title: "Delete", data: {placement: "bottom", confirm: "Really?"}, method: :delete, class: "icon ion-ios7-close-outline" %>
<% end %>
<!-- Page -->
<%= link_to "", new_admin_category_page_path(category), title: "New Page", data: {placement: "bottom"}, class: "icon ion-compose" %>
</div>
<!-- Pages -->
<%= render partial: "pages", locals: { id: category.name } %>
<!-- Children -->
<% if category.has_children? %>
<%= render partial: "category", locals: { collection: category.children } %>
<% end %>
</li>
<% end %>
</ol>
We also made a nested dropdown:
#app/helpers/application_helper.rb
def nested_dropdown(items)
result = []
items.map do |item, sub_items|
result << [('- ' * item.depth) + item.name, item.id]
result += nested_dropdown(sub_items) unless sub_items.blank?
end
result
end
That can be solved with resursion or with a special data structure. Recursion is simpler to implement, whereas a datastructure like the one used by the nested_set gem is more performant.
Recursion
First an example how it works in pure Ruby.
class Comment < Struct.new(:content, :replies);
def print_nested(level = 0)
puts "#{' ' * level}#{content}" # handle current comment
if replies
replies.each do |reply|
# here is the list of all nested replies generated, do not care
# about how deep the subtree is, cause recursion...
reply.print_nested(level + 1)
end
end
end
end
Example
comments = [ Comment.new(:c_1, [ Comment.new(:c_1a) ]),
Comment.new(:c_2, [ Comment.new(:c_2a),
Comment.new(:c_2b, [ Comment.new(:c_2bi),
Comment.new(:c_2bii) ]),
Comment.new(:c_2c) ]),
Comment.new(:c_3),
Comment.new(:c_4) ]
comments.each(&:print_nested)
# Output
#
# c_1
# c_1a
# c_2
# c_2a
# c_2b
# c_2bi
# c_2bii
# c_2c
# c_3
# c_4
And now with recursive calls of Rails view partials:
# in your comment show view
<%= render :partial => 'nested_comment', :collection => #comment.replies %>
# recursion in a comments/_nested_comment.html.erb partial
<%= nested_comment.content %>
<%= render :partial => 'nested_comment', :collection => nested_comment.replies %>
Nested Set
Setup your database structure, see the docs: http://rubydoc.info/gems/nested_set/1.7.1/frames That add the something like following (untested) to your app.
# in model
acts_as_nested_set
# in controller
def index
#comment = Comment.root # `root` is provided by the gem
end
# in helper
module NestedSetHelper
def root_node(node, &block)
content_tag(:li, :id => "node_#{node.id}") do
node_tag(node) +
with_output_buffer(&block)
end
end
def render_tree(hash, options = {}, &block)
if hash.present?
content_tag :ul, options do
hash.each do |node, child|
block.call node, render_tree(child, &block)
end
end
end
end
def node_tag(node)
content_tag(:div, node.content)
end
end
# in index view
<ul>
<%= render 'tree', :root => #comment %>
</ul>
# in _tree view
<%= root_node(root) do %>
<%= render_tree root.descendants.arrange do |node, child| %>
<%= content_tag :li, :id => "node_#{node.id}" do %>
<%= node_tag(node) %>
<%= child %>
<% end %>
<% end %>
<% end %>
This code is from an old Rails 3.0 app, slightly change and untested. Therefore it will probably not work out of the box, but should illustrate the idea.
This will be my approach:
I have a Comment Model and a Reply model.
Comment has_many association with Reply
Reply has belongs_to association with Comment
Reply has self referential HABTM
class Reply < ActiveRecord::Base
belongs_to :comment
has_and_belongs_to_many :sub_replies,
class_name: 'Reply',
join_table: :replies_sub_replies,
foreign_key: :reply_id,
association_foreign_key: :sub_reply_id
def all_replies(reply = self,all_replies = [])
sub_replies = reply.sub_replies
all_replies << sub_replies
return if sub_replies.count == 0
sub_replies.each do |sr|
if sr.sub_replies.count > 0
all_replies(sr,all_replies)
end
end
return all_replies
end
end
Now to get a reply from a comment etc:
Getting all replies from a comment: #comment.replies
Getting the Comment from any reply: #reply.comment
Getting the intermediate level of replies from a reply: #reply.sub_replies
Getting all levels of replies from a reply: #reply.all_replies
I've had various generally bad experience with the different hierarchy gems available for ActiveRecord. Typically you do not want to do this yourself as your queries will end up being very inefficient.
The Ancestry gem was ok, but I had to move away from it because 'children' is a scope and NOT an association. This means you CANNOT use nested attributes with it because nested attributes only work with associations, not scopes. That may or may not be a problem depending on what you are doing, such as ordering or updating siblings through the parent or updating entire subtrees/graphs in a single operation.
The most efficient ActiveRecord gem for this is the Closure Tree gem and I had good results with it, with the caveat that splatting/ mutating entire sub-trees was diabolical because of the way ActiveRecord works. If you don't need to compute things over a tree when doing updates then it is the way to go.
I've since moved away from ActiveRecord to Sequel and it has recursive common table expression (RCTE) support which is used by its built-in tree plugin. An RCTE tree is as fast as is theoretically possible to update (just modify a single parent_id as in a naive implementation) and querying is also typically orders of magnitude faster than other approaches because of the SQL RCTE feature it uses. It is also the most space efficient approach since there is just parent_id to maintain. I am not aware of any ActiveRecord solutions that support RCTE trees because ActiveRecord doesn't cover nearly as much of the SQL spectrum that Sequel does.
If you're not wedded to ActiveRecord then Sequel and Postgres is a formidable combination IMO. You will find out the deficiencies in AR when your queries become ever so slightly complex. There is always pain moving to another ORM as its not the out of the box stock rails approach but I have been able to express queries that I couldn't do with ActiveRecord or ARel (even though they were pretty simple), and generally improved query performance across the board 10-20 times over what I was getting with ActiveRecord. In my use case with maintaining trees of data its hundreds of times faster. That means tens to hundreds times less server infrastructure I need for the same load. Think about it.
You'd collect the reply's replies within each Reply iteration.
<% comment.replies do |reply| %>
<%= reply.content %>
<% reply_replies = Post.where("reply_id = #{reply.id}").all %>
<% reply_replies .each do |p| %>
<%= p.post %>
<% end
<% end %>
Though im not sure if it'd be the most conventional way cost-wise.
I'm trying to use RABL to build JSON output for the following index.html.erb file:
<% #halls.each do |hall| %>
<%= hall.name.capitalize %><br><br>
<% hall.days.each do |day| %>
<%= day.date.capitalize %>
<br><br>
<% day.meals.each do |meal| %>
<%= meal.name.capitalize %><br><br>
<% meal.foods.each do |food| %>
<%= food.name %> <br>
<% end %>
<br>
<% end %>
<% end %>
<% end %>
At this point, I've tried it a million different ways, and I was hoping someone could help me generate the code for the index.json.rabl file, as I'm completely and utterly stuck.
If you want to do "deep-nesting" of the child nodes, try this out:
collection #halls
# Use a custom node to get capitalized name
node :name do |hall|
hall.name.capitalize
end
# Child list of days
child :days do
node :date do |day|
day.date.capitalize
end
child :meals do
node :name do |meal|
meal.name.capitalize
end
child :foods do
# No need to use custom node because we don't need to do extra processing on the value (i.e capitalization is not required) and 'name' is a simple attribute on the model.
attribute :name
end
end
end
Otherwise, if you want all the child nodes all at the same level, then don't nest the do blocks.
Also, check out the RailsCast on RABL. One of the biggest concepts that took me a while to get is which object is in "scope" for the various RABL blocks (i.e. child block, node block, etc.) The RailsCast does a decent job of explaining the scoping of the object.
I want to edit multiple items of my model photo in one form. I am unsure of how to correctly present and POST this with a form, as well as how to gather the items in the update action in the controller.
This is what I want:
<form>
<input name="photos[1][title]" value="Photo with id 1" />
<input name="photos[2][title]" value="Photo with id 2" />
<input name="photos[3][title]" value="Custom title" />
</form>
The parameters are just an example, like I stated above: I am not sure of the best way to POST these values in this form.
In the controller I want to something like this:
#photos = Photo.find( params[photos] )
#photos.each do |photo|
photo.update_attributes!(params[:photos][photo] )
end
In Rails 4, just this
<%= form_tag photos_update_path do %>
<% #photos.each do |photo| %>
<%= fields_for "photos[]", photo do |pf| %>
<%= pf.text_field :caption %>
... other photo fields
UPDATE: This answer applies to Rails 2, or if you have special constraints that require custom logic. The easy cases are well addressed using fields_for as discussed elsewhere.
Rails isn't going to help you out a lot to do this. It goes against the standard view conventions, so you'll have to do workarounds in the view, the controller, even the routes. That's no fun.
The key resources on dealing with multi-model forms the Rails way are Stephen Chu's params-foo series, or if you're on Rails 2.3, check out Nested Object Forms
It becomes much easier if you define some kind of singular resource that you are editing, like a Photoset. A Photoset could be a real, ActiveRecord type of model or it can just be a facade that accepts data and throws errors as if it were an ActiveRecord model.
Now you can write a view form somewhat like this:
<%= form_for :photoset do |f|%>
<% f.object.photos.each do |photo| %>
<%= f.fields_for photo do |photo_form| %>
<%= photo_form.text_field :caption %>
<%= photo_form.label :caption %>
<%= photo_form.file_field :attached %>
<% end %>
<% end %>
<% end %>
Your model should validate each child Photo that comes in and aggregate their errors. You may want to check out a good article on how to include Validations in any class. It could look something like this:
class Photoset
include ActiveRecord::Validations
attr_accessor :photos
validate :all_photos_okay
def all_photos_okay
photos.each do |photo|
errors.add photo.errors unless photo.valid?
end
end
def save
photos.all?(&:save)
end
def photos=(incoming_data)
incoming_data.each do |incoming|
if incoming.respond_to? :attributes
#photos << incoming unless #photos.include? incoming
else
if incoming[:id]
target = #photos.select { |t| t.id == incoming[:id] }
end
if target
target.attributes = incoming
else
#photos << Photo.new incoming
end
end
end
end
def photos
# your photo-find logic here
#photos || Photo.find :all
end
end
By using a facade model for the Photoset, you can keep your controller and view logic simple and straightforward, reserving the most complex code for a dedicated model. This code probably won't run out of the box, but hopefully it will give you some ideas and point you in the right direction to resolve your question.
Rails does have a way to do this - I don't know when it was introduced, but it's basically described here: http://guides.rubyonrails.org/form_helpers.html#using-form-helpers
It took a bit of fiddling to alter the configuration properly for the case where there's no parent object, but this seems to be correct (it's basically the same as gamov's answer, but cleaner and doesn't allow for "new" records mixed in with the "update" records):
<%= form_tag photos_update_path do %>
<% #photos.each do |photo| %>
<%= fields_for "photos[#{photo.id}]", photo do |pf| %>
<%= pf.text_field :caption %>
... [other fields]
<% end %>
<% end %>
<% end %>
In your controller, you'll end up with a hash in params[:photos], where the keys are photo IDs, and the values are attribute hashes.
You can use "model name[]" syntax to represent multiple objects.
In view, use "photo[]" as a model name.
<% form_for "photo[]", :url => photos_update_path do |f| %>
<% for #photo in #photos %>
<%= render :partial => "photo_form", :locals => {f => f} %>
<%= submit_tag "Save"%>
<% end %>
<% end %>
This will populate input fields just like you described.
In your controller, you can do bulk updates.
def update
Photo.update(params[:photo].keys, params[:photo].values)
...
end
Indeed, as Turadg mentioned, Rack (Rails 3.0.5) fails if you mix new & existing records in Glen's answer.
You can work around this by making fields_for work manually:
<%= form_tag photos_update_path do %>
<% #photos.each_with_index do |photo,i| %>
<%= fields_for 'photos[#{i}]', photo do |pf| %>
<%= pf.hidden_field :id %>
... [other photo fields]
<% end %>
<% end %>
This is pretty ugly if you ask me, but it's the only way I found to edit multiple records while mixing new and existing records.
The trick here is that instead of having an array of records, the params hash gets a array of hashes (numbered with i, 0,1,2, etc) AND the id in the record hash. Rails will update the existing records accordingly and create the new ones.
One more note: You still need to process the new and existing records in the controller separately (check if :id.present?)