I have two models Users and Roles. I have setup a many to many relationship between the two models and I have a joint table called roles_users.
I have a form on a page with a list of roles which the user checks a checkbox and it posts to the controller which then updates the roles_users table.
At the moment in my update method I am doing this because I am not sure of a better way:
role_ids = params[:role_ids]
user.roles.clear
role_ids.each do |role|
user.roles << Role.find(role)
end unless role_ids.nil?
So I am clearing all the entries out then looping threw all the role ids sent from the form via post, I also noticed that if all the checkboxes are checked and the form posted it keeps adding duplicate records, could anyone give some advice on a more efficent way of doing this?
You can do a direct assignment, as that handles the dirty work for you:
user.roles = params[:role_ids].present? ? Role.find_all_by_id(params[:role_ids]) : [ ]
ActiveRecord should take care of creating new associations or removing those that are no longer listed. If anything precludes your join model from saving, such as a failed validation, you may have issues, but in most situations this should work as expected.
I hope you're using a has_many ..., :through for this one and not the deprecated has_and_belongs_to_many that keeps haunting so many Rails apps because of old example code.
Related
How do I associate two entries in a database that are connected through a many-to-many relationship in Rails?
I'm trying to associate Users and Issues for an issue tracker. I'm using has_and_belongs_to_many, not :through. I have a :user_id and :issue_id available to me, but there doesn't seem to be User.issues.find(id) or Issue.users.find(id) available to me. I have a route post "/", to: "home#create". I'm trying to make a create method in home_controller.rb.
From the look of it you're calling the method on the User class and not an instance.
If you want to get the issues connected to a user you need to fetch the user first:
User.find(id).issues
If you want to add a record to the association you can use the shovel method or any of the methods generated by the association macro:
User.find(id).issues << Issue.find(3)
User.find(id).issues.push(Issue.find(3))
User.find(id).issue_ids = [1, 2, 3]
Besides that you have a smattering of naming issues in your schema. Use snake_case everywhere in your database schema unless you have a good reason why you want to break the conventions and feel like explicitly configuring table and foreign key names.
I would also really question if you really want to use has_and_belongs_to_many. It should only really be used if you can't foresee that you ever will need to add additional attributes to the join table or never need to query the table directly - it seems pretty unrealistic that that would be true in an issue tracker. You want has_many through: - pretty much always.
I have a route post "/", to: "home#create". I'm trying to make a
create method in home_controller.rb.
Don't throw everything into a junk drawer controller. Think about your app in terms of resources that can be CRUD:ed and create controllers that handle just that resource. You should think about what the relation between a user and an issue is in your domain and how you can model it as an actual entity in the domain logic instead of just plumbing.
Maybe all I need to do is direct you to Rails Guides: Active Record Associations.
There is neither of these
User.issues.find(id)
Issue.users.find(id)
because when you are finding an issue or user by id, you don't use the association. Instead use these:
Issues.find(id)
Users.find(id)
Since the :id is unique this will work and should be what you want.
The only time you want to query issues or users using the association will be when you have the data for the other end of the relationship.
user = User.find(user_id)
issue = user.issues.where(id: issue_id)
Since the :id field is unique, this is the same as Issues.find(id). However if you want to get a collection of a user's issues with some other data, you can put the condition for that data in the where.
You can create an issue for a user this way:
user = User.find(user_id)
issue = User.issues.create( ... )
I am trying to create a Rails app and I have a database consisting of author and a quotation by that author.
Now different users can choose to destroy or kill quotations from the database however it must only be deleted for that particular user i.e other users should still be able to see quotes that they didn't delete even if another user did.
I know that I would need to implement cookies but other than that I am unsure how to proceed. Can anyone point me to a tutorial or give me some pointers to get started on this complex task?
You surely have a User model in your application - one 'Rails-like' way to go about this would be to add a has_and_belongs_to_many relationship between User and Quotation.
This creates a relationship between each individual user and 'their' quotations. This relationship can be deleted without actually deleting a quotation, so all quotations would still be available to other users. If you want each user to be able to see all quotations by default, you would need to set up the relationship in advance.
Assuming you are using Devise to log your users in, all you'd need to do then is to replace Quotation.all with current_user.quotations in whichever controller you are using to display quotations.
The Rails guide linked above is quite helpful but basically you just need to add something like the following:
class User
has_and_belongs_to_many :quotations
before_create :add_quotations
def add_quotations
self.quotations << Quotation.all
end
#etc...
end
class Quotation
has_and_belongs_to_many :users
#etc...
end
and then run a migration adding a new table called users_quotations with the columns user_id and quotation_id.
EDIT
As #Yule pointed out this wouldn't let users see any quotations that were created after they were, and it would be quite annoying to have to set up the join tables in advance, so a more efficient way would be to have an excluded_quotations join table instead. So users can see all quotations except the ones that they have excluded.
I am very new to Ruby on Rails.
I am trying to set up a relationship between a user model and a model of ten different items.
My goal is to have users be able to check off items in the items model and then have the ones that have been checked off display on their profile.
I have used the Michael Hartl Ruby on Rails tutorial up to
the point of creating microposts.
Any tips on tutorials that will help me complete this would be greatly appreciated.
Thanks!
Basically, what you want is:
A User has_and_belongs_to_many :items
Also, an Item has_and_belongs_to_many :users
This is many to many relationship. Since, a user can has many items, and an item can belong to many users too. In rails, here has_and_belongs_to_many will implicitly create a table items_users which will contain id's of both, establishing the relationship.
Read more about this association here - http://guides.rubyonrails.org/association_basics.html#the-has_and_belongs_to_many-association
Use checkbox tag for showing checkboxes for all the items. Documentation - http://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html#method-i-check_box
Based on whatever checkboxes are checked, save the records, establishing the relationship.
Done. :)
I don't know about other tutorials, if you've completed Hatel's then you have a very very good understanding of the rails framework as a whole. I would have an items_list model. Which had a user_id foreign key to associate itself with a user. Then I could have an items model which had an items_list foreign key to associate them to a list. Then items model could have a boolean field "active" or "checked" or whatever. Using these, and the associated relations, and some scopes, you can get what you want.
Just make sure to use the includes helper when you request this data, otherwise you'll easily get a N+1 problem.
http://guides.rubyonrails.org/active_record_querying.html#eager-loading-associations
I am using Rails 3.
I have a Product model and a Group model (a group has_many users, through membership).
I would like to build the new.html.erb form for the product model, and at the end of the form, I would like the user to be able to choose members from which group(s) can have access to the product he wants to add.
So, my goal is to list the groups to which the user belongs to, adding a checkbox for each of them. Then, create the associations between the product inserted and the different groups the user selected when the form is submitted, but I really do not understand how to achieve this, as all the documentation I have read use the BUILD or CREATE method that defines a new instance of group, instead of an existing one.
Is it possible with a nested form, and a HABTM relationship between product and group ? Or should I use a nested form with a has_many_through association using new model product_group_relationship ? Or should I use something else than a nested form ?
I'm quite new in Rails and a little bit lost here, so if some experienced guy could guide me a little bit, it would be very much appreciated!
The form_for helper comes with a nice package of extra methods like: fields_for wich makes you able to add nested attributes for has_many_through relations.
I suggest reading these:
http://apidock.com/rails/ActionView/Helpers/FormHelper/fields_for
And make sure you set your model validations accordingly
I am building a blog-style application in Rails 3 where multiple users are able to post some news. After the login (which is realized with "Authlogic") the user values are stored in a own model called e.g. "UserSession". The form for the post contains title, content etc. and the username should be stored with a hidden form.
I think that the two models don't need to be related to each other (by that I mean a :has_many - :belongs_to relationship) because there isn't any further usage for that information.
Do I really not need this relation? And how could I realize the form?
For Authlogic is it important to remember that the 'UserSession' does not correspond to any database tables (i.e. you would never use a has_many or has_one 'UserSession'). I think the relationship you are looking for is:
User has many Posts
Blog belongs to User
The reason? It is always a good idea to associate a record with the 'owner' so that the owner can later modify or delete the record. I hope this helps.