Reverse linking Child model to Parent model in Rails 4 - ruby-on-rails

Im not sure how to name this question, but Im stucked with kind of an reverse relations in Rails 4. Let me explain it on a real-life example
Order has_many OrderFiles and OrderFile belongs_to Order
My app logic is like this (marketplace like):
User upload some file on the /create_new_order/ page. OrderFile object is saved to the database using form_for OrderFile.new
User searching for the Performer of the Order, apply filters, etc..
User click "Make order" and on certain person. Order object is created
But, how do I link OrderFile to the Order?
It's quite simple when the Order is created first. But when the File is first, how may rails know which order_id link to?

Related

how to continue after the nested model forms railscasts?

I followed the railscasts nested model form part 1, making some changes to have it work in rails 4. Basically, I created 3 models: Quiz, Question, and Answer, and they all belong_to the model intuitively above them. A form in the new action is used to create the quiz itself.
However, I'm at a bit of loss on how to proceed now. After creating the quiz, the show view looks like this:
done by iterating through #quiz.questions and #quiz.questions.answers and just displaying them on the page with their respective content attributes.
That's great for displaying just the questions and answers, but it doesn't accept user input at all. How do I make it so the user can use radio buttons to select an answer, and have it submit SOMEWHERE to save the results for grading and future reference for the user?
I've actually tried to create a form simply within the show action and have it save to another model but I got stuck extremely quickly. I'm finding it really difficult to both display the results AND accept user input for the displayed results. I also can't figure out a good way to save this data. Making another 3 models with the equivalent of Questions having something like a user_answer attribute seems difficult to implement and messy. I'm a beginner of the grandest caliber so any help would be great!
Nachime, your data model is good so far from what I can tell. Now you will want to link the answers to the users via many-to-many relationship. Note: this assumes that users will only take each quiz once.
Your next data model version will have a users_answers table containing user_id and answer_id. You can access the relative models using the has_many :through association so that each user has_many :answers, through: :users_answers.
The quiz will essentially just link the logged in user to the array of answers selected.

Ruby on Rails Model Relationships

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

In a single form, linking two instances of two models with habtm

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

Multiple non-related models in one Rails form

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.

Live Search / auto_complete + HABTM = possible?

I am attempting to add in a form field that should allow me to add a record into a join table. The table name contains the ids of the following:
log_id
node_id
So naturally, my models is setup as follows:
class Log
has_and_belongs_to_many :nodes
end
class Node
has_and_belongs_to_many :nodes
end
The objective is that when I create a log, I should be able to associate it with an number of nodes (ergo, servers). And since there is a lot of nodes on hand, it seems to make sense to have a textfield where when you enter a node name, it will pop-up a list of nodes to choose from. However, I am having some difficulty getting that accomplished.
I know how to use the autocomplete plugin, (that had came with Rails), but it seems to only accept a string and not with the id - and apparently not across models. I know how to do an AJAX search (though I am not that familiar with Javascript), but again, getting that ID becomes an issue.
I think that in either case, I may be able to figure how to get that value and put that in - the uncertainty is whether one or the other is the correct approach to getting that value. Which one should I concentrate on? Or is HABTM even appropriate in this?

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