I'm still very new to rails programming, and it's my first question at stackoverflow.
I have models Group and Product like so:
class Group < ActiveRecord::Base
has_many :products
end
class Products < ActiveRecord::Base
belongs_to :Group
end
Now, I have some data filled with multiple products in multiple groups. What should I do when I want to move one of the product from one group to another?
-Should I be using has_many :through relationship (and is that the only suggested way)? (Because I think that dealing with 3 tables are more complicated and calculation-intensive than just 2 tables.)
-Is there a preferred way for doing this?
Here's the things I've tried:
-Setting nil to group_id in products and updating it to remove the association which worked. I'm just not sure if this is the right way of disassociating an object.
-I tried creating a custom function in groups_controller.rb like below. (and I know that this may not be the right way of doing it, but I'm a bit desperate)
in the /view/groups/show.html.erb I have
<% form_tag group_add_reference_path(#group.id), :method => 'put' do %>
<%= hidden_field_tag 'params[group_id]', "#{#group.id}" %>
<div class="field">
<%= collection_select('params', 'product_id', Product.where(:group_id => nil), :id, :name) %>
</div>
<div class="actions">
<%= submit_tag "assign", :name => nil %>
</div>
<% end %>
and in the groups_controller.rb I have
def add_reference
#group = Group.find(params[:group_id])
#product = Product.find(params["product_id"])
#group.products << #product
end
-I've read Detailed Association Reference chapter of association_basics in railsguides, and since it has collection<<(object) function added, I though I should be able to do something close to above. (which is not working because #product seems to be nil for some reason, and even if I set it to a valid ID and hardcode it, it fails on the line after that)
I think you may have answered this yourself :
If they can only be associate with one group at a time, do this :
def add_reference
#product = Product.find(params[:product_id])
#product.update_attribute("group_id", params[:group_id])
end
Moving a product from one group to another requires just one simple thing: Changing the product's group_id to "point" to the new group, that is, the group_id column should contain the new group's id after the change. Mr Trip's answer shows you the actual code.
I found out why it wasn't working.
in the above code that I wrote, the collection_select returns a hash itself.
therefore:
#product = Product.find(params[:product_id])
doesn't work (because all request parameters also come in a hash).
What I had to do was to access the recursive hash (not sure if the word is correct) like:
#product = Product.find(params[:params][:product_id])
Or, use where instead of find like:
#product = Product.where(params[:params]).limit(1)
and it works!!
Thank you for all of the comments. That kept me working on it.
Related
is a little project and I try to associate patient model with consultations. one patient has_many :consultations, in my form I have:
<%= f.association :patient %>
I pass the id parameter from the patient to the action 'new' in this way:
<%= link_to new_consultum_path(:id => #patient.id) %>
And in the view I have:
How can I make that the f.association field take the correspondent patient_id automatically?
How can I be sure that the patient_id is the current patient?
If I want to hide this field is that ok if I put
instead of
Is a better way to do this?
And why in the view shows me # patient:0x007f4e7c32cbd0 ?
thanks for your help.
And why in the view shows me # patient:0x007f4e7c32cbd0
This is a Patient object.
It means you need to call an attribute of this object - EG #patient.name.
--
f.association field take the correspondent patient_id automatically
This might help:
It looks like Organization model doesn't have any of these fields: [
:to_label, :name, :title, :to_s ] so SimpleForm can't detect a default
label and value methods for collection. I think you should pass it
manually.
#app/models/patient.rb
class Patient < ActiveRecord::Base
def to_label
"#{name}"
end
end
Apparently, you need to have either title, name or to_label methods in your model in order for f.association to populate the data.
-
How can I be sure that the patient_id is the current patient?
If you're having to verify this, it suggests inconsistencies with your code's structure. If you need the patient_id to be set as the current patient, surely you could set it in the controller:
#app/controllers/consultations_controller.rb
class ConultationsController < ApplicationController
def create
#consultation = Constultation.new
#consultation.patient = current_patient
#consultation.save
end
end
I can provide more context if required.
You want to associate consultations to patients using fields_for, which is similar to form_for, but does not build the form tags.
It you start with your patient object, you can iterate through the consultation associations binding it to form fields as you go.
it would look something like this
<%= form_for #patient do |patient_form| %>
<% patient_form.text_field :any_attribute_on_patient %>
<% #patient.consultations.each do |consultation| %>
<%= patient_form.fields_for consultation do |consultation_fields| %>
<% consultation_fields.text_field :any_attribute_on_consulatation %>
<% end %>
<% end %>
<% end %>
Sorry, the code may not be exactly right.
Check out the docs for field_for here
You will also have to set accepts_nested_attributes_for consultations on patient. When you set accepts_nested_forms_for, Rails will automatically update the associated consultations object to the patient and save any edits you have made. You DEFINITELY want to use accepts_nested_attributes_for most nested form handling of this type.
I'm adding a new model to my equasion and I'm wondering if there is a way to associate two models into one model then display any/all results within a view. For example, here is what I've currently have;
#tweet_category.order("position").each do |tweet|
<%= tweet.title %>
end
just a short example... now what if I added facebook into this. I was first thinking of creating a model thats named stuff then associate it to tweet_category and facebook_category like so;
class Stuff < ActiveRecord::Base
attr_accessible :title
belongs_to :user
has_many :tweet_category
has_many :facebook_category
end
Now in my controller I'm guessing I would do the following;
class StuffController < ApplicationController
def index
#stuff_list = Stuff.find(:all)
end
end
and in my view I would just simply do the following from above view;
#stuff_list.order("position").each do |stuff|
<%= stuff.title %>
end
am I understanding the logic here??? would that work having two models / two tables db.. etc..
First of all, I don't understand why you would need that "stuff" model. It belongs to users and has_many tweet_category and facebook_category, and just does nothing but offering a "title", when your User model could do the job ( I mean, each user could have many tweets and fb category, instead of having one or several "stuff" which has/have many of them ).
Anyway, if you want to make links between your models and then display everything in a view, first in your User model you just have to do :
class User < ActiveRecord::Base
...
has_many :facebook_categories #( I don't know how rails would pluralize it, btw, I'm just making an assumption )
has_many :tweeter_categories
end
and
class Facebook_category
...
belongs_to :user
end
and do the same fot the tweeter category
Then in your controller :
def show_everything #Here it's a custom action, but you can call it wherever you want
#users = User.all
end
And finally in your view :
<% #users.each do |user| %>
<% user.facebook_categories.all.each do |fb_c| %>
<%= fb_c.title %>
<% end %>
<% user.tweeter_categories.all.each do |t_c| %>
<%= t_c.title %>
<% end %>
<% end %>
Maybe just try to grab a better name for your models, so the pluralization doesn't get messy ( and I saw that the ".all" method is deprecated, so maybe replace it with something
Hope it helps !
Edit :
Basically, when you're doing
#users = User.all
What rails' doing is putting every hash defining every "User" in an array. So, if you want to mix two tables' arrays inside a single array, you can do something like this :
#categories = [] << Facebook_category.all, Tweeter_category.all
You will then have an array ( #category ), filled with 2 arrays ( one ActiveRecord relation for Facebook_category and one for Tweeter_category ). Themselves filled with hashes of their model. So, what you need to do is :
#categories.flatten!
Here's the API for what flatten does ( basically removing all your nested arrays inside your first tarray )
Now, you got a single array of hashes, being the informations from both your model's instances. And, if these informations can be ordered, in your view, you just have to :
<% #categories.order("updated_at").each do |i| %>
<%= i.title %>
<% end %>
I'm building a martial arts related database, currently I have the following associations set up:
Student has_and_belongs_to_many :styles
Style has_many :ranks
Student has_many :ranks, through: :gradings (and vice versa)
I'm generating a form as follows, depending on the student's styles:
So the headings are generated by the Style model (Tai Chi, Karate...), then their rankings listed below (taken from the Rank model), and the "Dojo" and "Date" fields should belong to the Grading model once created.
The question: I know how to build a form that creates one association (or one association + its children), but how do I build a form that creates multiple associations at once?
Also, what would be a clean way to implement the following:
Only lines which are ticked become associations
Dojo and date must be filled in for ticked lines to save successfully
If a line is unticked it will destroy any previously created associations
This is what I've currently implemented to retrieve the correct records:
class GradingsController < ApplicationController
before_filter :authenticate_sensei!
def index
#student = Student.includes(:styles).find(params[:student_id])
#ranks = Rank.for_student_styles(#student)
split_ranks_by_style
end
private
def split_ranks_by_style
#karate = #ranks.select_style("Karate")
#tai_chi = #ranks.select_style("Tai Chi")
#weaponry = #ranks.select_style("Weaponry")
end
end
# Rank model
def self.for_student_styles(student)
includes(:style).where("styles.id in (?)", student.styles.map(&:id))
end
def self.select_style(style)
all.map { |r| r if r.style.name == style }.compact
end
Complicated forms like this are best handled in a service object initiated in the primary resource's create or update action. This allows you to easily find where the logic is happening afterwards. In this case it looks like you can kick off your service object in your GradingsController. I also prefer formatting a lot of the data in the markup, to make the handling easier in the service object. This can be done a'la rails, by passing a name like "grade[style]" and "grade[rank]". This will format your params coming in as a convenient hash: {grade: {style: "karate", rank: "3"}}. That hash can be passed to your service object to be parsed through.
Without really grasping the full extent of your specific requirements, let's put together an example form:
<%= form_for :grading, url: gradings_path do |f| %>
<h1><%= #rank.name %></h1>
<%- #grades.each do |grade| %>
<div>
<%= hidden_field_tag "grade[#{grade.id}][id]", grade.id %>
<%= check_box_tag "grade[#{grade.id}][active]" %>
...
<%= text_field_tag "grade[#{grade.id}][date]" %>
</div>
<%- end %>
<%= submit_tag %>
<%- end %>
With a form like this, you get your params coming into the controller looking something like this:
"grade"=>{
"1"=>{"id"=>"1", "active"=>"1", "date"=>"2013-06-21"},
"3"=>{"id"=>"3", "date"=>"2013-07-01"}
}
Nicely formatted for us to hand off to our service object. Keeping our controller nice and clean:
class GradingsController < ApplicationController
def index
# ...
end
def create
builder = GradeBuilder.new(current_user, params['grade'])
if builder.run
redirect_to gradings_path
else
flash[:error] = 'Something went wrong!' # maybe even builder.error_message
render :action => :index
end
end
end
So now we just need to put any custom logic into our builder, I'd probably recommend just making a simple ruby class in your /lib directory. It could look something like this:
class GradeBuilder
attr_reader :data, :user
def self.initialize(user, params={})
#user = user
#data = params.values.select{|param| param['active'].present? }
end
def run
grades = data.each{|entry| build_grade(entry)}
return false if grades.empty?
end
private
def build_grade(entry)
grade = Grade.find(entry['id'])
rank = grade.rankings.create(student_id: user, date: entry['date'])
end
end
There will obviously need a lot more work to pass all the specific data you need from the form, and extra logic in the GradeBuilder to handle edge cases, but this will give you a framework to handle this problem in a maintainable and extensible way.
I'm not familiar on how forms work.
Example Scenario
Lets say users can create surveys but after they are created cannot edit them but only add questions to them. This is done by using the edit action on the Survey.
class Survey < ActiveRecord::Base
has_many :questions
accepts_nested_attributes_for :questions
end
class Question < ActiveRecord::Base
belongs_to :survey
belongs_to :user
end
# QuestionsController
def edit
#survey = Survey.find(params[:id])
#survey.questions.build
end
def update
#survey = Survey.find(params[:id])
#survey.update_attributes(params[:survey])
redirect_to ...
end
Then the form should be:
<%= form_for #survey do |f| %>
# No surveys fields on this form!
<% f.fields_for :questions do |builder| %>
<%= render "question_fields", :f => builder %>
<% end %>
<%= f.submit "Submit" %>
<% end %>
Now does this leave the Survey's values vulnerable or open to hacking even if I want the survey's fields to be unusable after creation?
What about in general? Can model values still be edited when their not on the form? What's the logic behind this and how would I know they couldn't?
Thanks, just a newbie trying to learn.
Yes, those attributes can still be edited by submitting them as parameters to your form, even if you don't provide fields for them.
To protect against that, you can protect the attributes explicitly (in later versions of Rails, this is the default). In your Survey model, add
attr_protected :name # or whatever other attributes that model has
This prevents mass assignments for those attributes, both for create and update. To allow creating, you'll have to assign those attributes explicitly in the create action of your SurveyController:
def create
#survey = Survey.new # instead of Survey.new(params[:survey])
#survey.name = params[:survey][:name]
#survey.save
# etc
end
EDIT:
As blackbird07 points out, the better approach is to whitelist those attributes that you want to allow mass-assignment for, instead of the blacklist approach described here.
In short: Yes, they can be edited with a well-crafted POST request using either a tool like curl or by editing the HTML form with browser developer tools. The reason is that you use update_attributes for doing the update, which will update all attributes supplied in the params parameter. This is called mass-assignment.
It is recommended that you whitelist the attributes you want to be editable: http://guides.rubyonrails.org/security.html#mass-assignment
Also, it is highly recommended that your read this article about "Strong parameters: Dealing with mass assignment in the controller instead of the model"
You can also protect against mass assignment by putting
config.active_record.whitelist_attributes = true
in your config/application.rb
Now all atttrbitues must be explicitly labeled accessible. It does this by creating an empty whitelist of attributes for all models in your app.
To simplify things, I have 3 tables :
Person
has_many :abilities, through => :stats
Ability
has_many :people, through => :stats
Stats
belongs_to :people
belongs_to :abilities
Stats has an extra attribute called 'rating'.
What I'd like to do is make an edit person form that always lists all the abilities currently in the database, and lets me assign each one a rating.
For the life of me, I can't figure out how to do this. I managed to get it to work when creating a new user with something like this:
(from the people controller)
def new
#character = Character.new
#abilities = Ability.all
#abilities.each do |ability|
#person.stats.build(:ability_id => ability.id )
end
end
From the people form:
<% for #ability in #abilities do %>
<%= fields_for "person[stats_attributes]" do |t| %>
<div class="field">
<%= t.label #ability.name %>
<%= t.hidden_field :ability_id, :value => #ability.id, :index => nil %>
<%= t.text_field :rating, :index => nil %>
</div>
<% end %>
<% end %>
This successfully gives me a list of abilities with ratings boxes next to them, and lets me save them if i'm making a new user.
The problem is that if I then load up the edit form (using the same form partial), it doesn't bring back the ratings, and if I save, even with the exact same ratings, it creates duplicate entries in the stats table, instead of updating it.
I realize I'm a terrible programmer and I'm probably doing this the wrong way, but how do I get the edit form to recall the current ratings assigned to each ability for that user, and secondly how do i get it to update the rating instead of duplicating it if the combination of person and ability already exists?
Shouldn't that be
Character
has_many :stats
has_many :abilities, through => :stats
Ability
has_many :stats
has_many :characters, through => :stats
Stat
belongs_to :character
belongs_to :ability
?
Also, is it Person or Character? You refer variously to both. (I'm going to go with Character in my answer)
I think you've fallen foul of the "I'll try to make a simplified version of my schema in order to attempt to illustrate a problem but instead make things more complex and muddle the issue by screwing it up so it doesn't make sense" syndrome. Anyway, there's a couple of issues i can see:
1) first thing is that you're adding all the possible abilities to a character as soon as they're created. This is silly - they should start out with no abilities by default and then you create join table records (stats) for the ones they do have (by ticking checkboxes in the form).
2) A simple way to manipulate join records like this is to leverage the "ability_ids=" method that the has_many :abilities macro gives you - referred to as "collection_ids=" in the api http://railsbrain.com/api/rails-2.3.2/doc/index.html?a=M001885&name=has_many
In other words, if you say
#character.ability_ids = [1,12,30]
then that will make joins between that character and abilities 1, 12 and 30 and delete any other joins between that character and abilities not in the above list. Combine this with the fact that form field names ending in [] put their values into an array, and you can do the following:
#controller
def new
#character = Character.new
#abilities = Ability.all
end
#form
<% #abilities.each do |ability| %>
<div class="field">
<%= t.label #ability.name %>
<%= check_box_tag "character[ability_ids][]" %>
</div>
<% end %>
#subsequent controller (create action)
#character = Character.new(params[:character]) #totally standard code
Notice that there's no mention of stats here at all. We specify the associations we want between characters and abilities and let rails handle the joins.
Railscasts episodes 196 and 197 show how to edit several models in one form. Example shown there looks similar to what you're trying to do so it might help you out (same episodes on ascicasts: 196, 197).