New web developer here, and I think I may be missing some very fundamental knowledge. Given the code
> def create
> #post = Post.new(post_params)
> if #post.save
> redirect_to #post
> else
> render "new"
> end
end
after saving the post, it redirects to show page, due to this "redirect_to #post", how can I do the same thing with "redirect_to: action => "show", :id => 5" I have to pass the ID now, how to retrieve the ID from #post object?
so only I can pass the Id to redirect page.
can I stop the compiler here, like debugger in js?
To answer your question of "I may be missing some very fundamental knowledge" yes, you might be. An object in Rails like #post is usually a database record. You can access any of it's columns in the DB by using the column name as a method:
#post.id
returns:
5 #or whatever the post id is.
If your post table has a column of "title" you can access it with
#post.title
returns:
"This is an awesome post"
I would highly recommend you view some Ruby and some Rails tutorials. Everything in Ruby is an object. Rails uses a lot of conventions so you can do things without having to write code for it, it's already there for you. When you get into Rails ActiveRecord Relations you'll see that relations expand this to give you related table information as methods. For Example:
Post.rb
...
belongs_to :user
User.rb
...
has_many :posts
Gives you methods like:
#post.user #returns the user object with all of its info
#post.user.username #returns the value of that column for that user
#post.user.posts #returns an array of Post objects that belong to the owner of that post.
Ruby has a pry-byebug gem for debugging. It's a combination REPL (Pry) and core debugger (byebug) that work very powerfully together.
Getting the id of a successfully saved ActiveRecord model is just #post.id, however the rails methods like redirect_to will take the object itself just fine, as #Beartech has mentioned, above. The documentation shows a variety of ways to use it, for convenience:
redirect_to action: "show", id: 5
redirect_to #post
redirect_to "http://www.rubyonrails.org"
redirect_to "/images/screenshot.jpg"
redirect_to posts_url
redirect_to proc { edit_post_url(#post) }
Related
I am trying to make a column in my Posts table which is an array. I want the array to store the current_user's email (or id/name etc...).
However, for some reason I cannot get the current_user's email to append to the array.
The array column is called claimed_users and the purpose of the column is to store the user_email of all users who have "claimed" the post. This way I can implement code to prevent them from claiming more than one post amongst other things.
I currently have this in my View:
<%= link_to "Claim This Post", { controller: :posts, action: :claim, post_id: #post.id, user_id: current_user.id },{ class: 'btn btn-default'} %>
And This for my action in PostsController:
def claim
#post = Post.find(params[:post_id])
#user = User.find(params[:user_id])
#post.increment!(:claim)
#post.claimed_users << current_user.id
if #post.claim < 99
redirect_to #post, notice: 'You have successfully claimed this post. You have 8 hours to post a response'
else
redirect_to #post, notice: 'Sorry, this post already has enough claims'
end
end
I added "serialize: claimed_users, Array" in my Posts model:
class Post < ActiveRecord::Base
belongs_to :user
has_many :responses
has_many :top_responses
has_many :claims
serialize :claimed_users, Array
end
However, I still have no luck. When I look in the database using the Rails console I still get "claimed_users: nil".
Before, I was getting "claimed_users: "--- []\n"" but that changed when I added some code though I'm not exactly sure where as I have tried a lot of things so far and read a lot of SO questions and google results to no avail.
I explored the idea of creating a new Model/Controller for Claims/Claimed_Users but it doesn't make much sense when I think about it.
Any help is greatly appreciated! I'm still fairly new to programming.
In my Rails app I have an invoices_controller.rb with these actions:
def new
#invoice = current_user.invoices.build(:project_id => params[:project_id])
#invoice.build_item(current_user)
#invoice.set_number(current_user)
end
def create
#invoice = current_user.invoices.build(params[:invoice])
if #invoice.save
flash[:success] = "Invoice created."
redirect_to edit_invoice_path(#invoice)
else
render :new
end
end
Essentially, the new method instantiates a new invoice record plus one associated item record.
Now, what sort of method do I need if I want to duplicate an existing invoice?
I am a big fan of Rails's RESTful approach, so I wonder if I should add a new method like
def duplicate
end
or if I can use the existing new method and pass in the values of the invoice to be duplicated there?
What is the best approach and what might that method look like?
Naturally, you can extend RESTful routes and controllers.
To be rally RESTful, it is important to look exactly, what you want.
i.e. if you want a new invoice and use an existing one as a kind of template, then it is comparable to a new action, and the verb should be GET (get the input form). As is it based on an existing invoice, it should reference that object. After that you would create the new invoice in the usual way.
So in you routes:
resources :invoices do
member do
get 'duplicate'
end
end
giving you a route duplicate_invoice GET /invoices/:id/duplicate(.format) invoices#duplicate
So in your view you can say
<%= link_to 'duplicate this', duplicate_invoice_path(#invoice) %>
and in your controller
def duplicate
template = Invoice.find(params[:id])
#invoice= template.duplicate # define in Invoice.duplicate how to create a dup
render action: 'new'
end
If I understand correctly your question you can:
resources :invoices do
collection do
get 'duplicate'
end
end
and with this you can do:
def duplicate
# #invoice = [get the invoice]
#invoice.clone_invoice
render 'edit' # or 'new', depends on your needs
end
clone_invoice could be a custom method which should have a invoice.clone call in your custom method.
If you question if you can use additional methods except REST, you absolutely can. Google, for example, encourage developers to use something, what they call "extended RESTful" on GoogleIO, http://www.youtube.com/watch?v=nyu5ZxGUfgs
So use additional method duplicate, but don't forget about "Thin controllers, fat models" approach to incapsulate your duplicating logic inside model.
When I look at examples of Rails controllers, I usually see something like this:
class WidgetController < ActionController::Base
def new
#widget = Widget.new
end
def create
#widget = Widget.new(params[:id])
if #widget.save
redirect_to #widget
else
render 'new'
end
end
end
This works, but there's a couple problems:
Routes
If I add widgets to my routes.rb file:
Example::Application.routes.draw do
resources :widgets
end
GET /widgets/new will route to new and POST /widgets will route to create.
If the user enters incorrect information on the new widget page and submits it, their browser will display a URL with /widgets, but the new template will be rendered. If the user bookmarks the page and returns later or refreshes the page, the index action will be called instead of the new action, which isn't what the user expects. If there's no index action or if the user doesn't have permission to view it, the response will be a 404.
Duplication of code
As a contrived example, let's say I had some tricky logic in my new method:
def new
#widget = Widget.new
do_something_tricky()
end
Using the current approach, I'd duplicate that logic in new and create. I could call new from create, but then I'd have to modify new to check if #widget is defined:
def new
#widget ||= Widget.new
do_something_tricky()
end
Plus, this feels wrong because it reduces the orthogonality of the controller actions.
What to do?
So what's the Rails way of resolving this problem? Should I redirect to new instead of rendering the new template? Should I call new inside of create? Should I just live with it? Is there a better way?
I don't think this is a problem in "the rails way" and there is no builtin functionality to allow this without getting your hands dirty. What does a user expects when bookmarking a form they just submitted and had errors? Users don't know better, and they shouldn't bookmark a failed form.
I think redirecting to new_widget_path is the cleanest solution. Yet, you should keep the errors and display them on the form. For this I recommend you keep the params in session (which I expect to be smaller than a serialized Widget object).
def new
#widget = widget_from_session || Widget.new
end
def widget_from_session
Widget.new(session.delete(:widget_params)) if session[:widget_params].present?
end
private :widget_from_session
# Before the redirect
session[:widget_params] = params
The code is self explanatory, Widget.new will only be called when widget_from_session returns nil, this is when session[:widget_params] is present. Calling delete on a hash will return de deleted value and delete it from the original hash.
UPDATE Option 2
What about submitting the form using ajax? Your controller could benefit from:
respond_to :html, :json
...
def create
#widget = Widget.new params[:widget]
#widget
respond_with #widget, location: nil
end
Based on the response code (which is set by Rails: 201 Created or 422 Unprocessable Entity), you could show the errors (available in the body of the response when validations fail) or redirect the user to #widget
This is how StackOverflow does it: https://stackoverflow.com/questions/ask. They submit the form asynchronously.
In general, I think the Rails way of solving the problem would be to put the tricky method onto the model or as a helper method, so the controller stays "thin" and you don't have to make sure to add custom behavior to both #new and #create.
EDIT: For further reading, I'd recommend the "Rails AntiPatterns" book, as they go through a lot of these common design issues and give potential solutions.
you put do_something_tricky() in its own method and call it inside the create action (but only when you're rendering the new template, ie when validation fails).
As for the bookmark issue, I don't know a good way to prevent that but to modify the routes and set the create action to the new action but using POST
get '/users/new' => 'users#new'
post '/users/new' => 'users#create'
UPDATE: using resources
resources :platos, except: :create do
post '/new' => 'plates#create', on: :collection, as: :create
end
then you can use create_platos_path in your forms
You don't need to write same function in two action , use before_filter instead.
If you want to have "widget_new_url" after incorrect submission then in your form add url of new widget path something like :url => widget_new_path .
Rails takes the url from Form .
I have this problem before, so I use edit action instead.
Here is my code.
Routes:
resources :wines do
collection do
get :create_wine, as: :create_wine
end
end
Controller:
def create_wine
#wine = Wine.find_uncomplete_or_create_without_validation(current_user)
redirect_to edit_wine_path(#wine)
end
def edit
#wine = Wine.find(params[:id])
end
def update
#wine = Wine.find(params[:id])
if #wine.update_attributes(params[:wine])
redirect_to #wine, notice: "#{#wine.name} updated"
else
render :edit
end
end
Model:
def self.find_uncomplete_or_create_without_validation(user)
wine = user.wines.uncomplete.first || self.create_without_validation(user)
end
def self.create_without_validation(user)
wine = user.wines.build
wine.save(validate: false)
wine
end
View:
= simple_form_for #wine, html: { class: 'form-horizontal' } do |f|
= f.input :complete, as: :hidden, input_html: { value: 'true' }
What I did is create a new action 'create_wine' with get action.
If user request 'create_wine', it will create a new wine without validation and redirect to edit action with a update form for attributes and a hidden field for compele .
If user has create before but gave up saving the wine it will return the last uncompleted wine.
Which means whether use save it or not, the url will be the same to /wines/:id.
Not really good for RESTful design, but solve my problem. If there is any better solution please let me know.
Perhaps this can even become a Community Wiki, but I would love a detailed description of how the controller works - or rather, how I can get it to do what I want it to do.
I understand the general structure of MVC and how the model stores the db structure, and the controller interacts with the db and passes info to the view.
However, I am puzzled (on a fundamental level) about how to accomplish simple tasks using my controller. I know that if I want to create a new record for a model/object, I just do object = Object.new(:name => "Object Name") in the Rails console.
But how on earth would I do that in the CRUD elements of the controller and why?
Please use a simple example - e.g. showing a user the balance of their bank account (I know there are many complexities surrounding this, but ignore them for the sake of this explanation). What would the model look like (just include: Name, Address, Transaction Type (Deposits/Withdrawals), Balance).
What would a view look like? What would the controller look like? Any choices you make (like using a form) please explain them. Why would you use a form, as opposed to a drop down menu and (in layman terms) how does the form or drop down menu interact with the controller? How do I get the info captured there to the db and why am I doing it that way?
I know this sounds like a lot to ask, but I have done RailsTutorial.org, watched many Railscasts, read the Rails guides, and read many other tutorials and still have some basic gaps in my understanding of the way Rails works and why.
Thanks in advance.
I don't know how much more help I can be, but I understand your pain having just come to rails myself. The article recommended by ghoppe, "Skinny Controller, Fat Model" explains the function of Ms Vs & Cs nicely. Seeing as that does not fully answer your question I will try to explain the mechanics of each structure.
Model
class Account < ActiveRecord::Base
belongs_to :user
validates_presence_of :address
def name # Account does not have a name field, but User does so I will make a name method for Account and feed it name of the user it belongs to.
user = self.user # Account gets the user method with the <belongs_to :user> association
# note: Rails expects Accounts to have a user_id field so it can perform the "magic" to associate Accounts with Users
if user.name
return user.name
else
return nil
end
end
end
The model describes your object. Like an object in any OOP language you want to put all of your object logic here. This includes the rails helpers for association(has_one, belongs_to, ...) and validation, as well as any other method or library you want the object to be able use throughout your Models Views and Controllers.
Controller
class AccountsController < ApplicationController
before_filter :name, :only => :edit, :destroy # #account.name will be executed before the edit or destroy method(action) can be invoked on #account. If the user who has the account has a name the action will execute.
def index # This is a RESTful action and is mapped by Rails by default to an HTTP GET request. Rails expects an index.html.erb or index.haml.erb or index.something in the Accounts view to map this action to.
#accounts = Account.all # #accounts is an instance variable and will be accessible in the view this action is mapped to.
end
def show
#account = Account.find(params[:id]) # params[:id] is passed to the controller from the view. The params hash is the primary tool form moving data from a form or URL into a controller. Anytime you click on the link_to the show or edit action of an object Rails will put that objects id in the params hash and call the appropriate action in that objects controller. If you click the show link on an account it will call this action. Now the instance variable in the view show.html.erb will hold a single account instead of an array
end
def new
#account = Account.new # This initializes a new account with all the fields set to blank unless you specified a default in your migration. This account has not been save to the db yet. It is ready for a user to fill in.
respond_to do |format| # Rails can automatically respond differently to different client request. If a client i.e browser wants HTML rails responds with HTML. If a client e.g. an API want XML Rails responds with XML.
format.html # new.html.erb #
format.xml { render :xml => #account }
end
end
def edit
#account = Account.find(params[:id]) # Same as show, but mapped to a different view
end
def create # Finally we have a POST. All the prior actions were GETs, but now we are saving some data to the db.
#account = Account.new(params[:account]) # The :account key is special. It is a hash of hashes. It is populated by the form fields in new.html.erb. To access a specific field such as address we say <params[:account][:address]> and whatever the user entered in the address field in the View is at out fingers in the Controller.
respond_to do |format|
if #account.save # If the validations pass and the account gets saved redirect to the show page of the new record, otherwise refresh/render the new page (hopefully showing what error caused the record to fail to save).
format.html { redirect_to(#account, :notice => 'Account was successfully created.') }
format.xml { render :xml => #account, :status => :created, :location => #account }
else
format.html { render :action => "new" }
format.xml { render :xml => #account.errors, :status => :unprocessable_entity }
end
end
end
def update # This is another of the seven RESTful Rails actions and results in a PUT request because you are updating an existing record
#account = Account.find(params[:id])
respond_to do |format|
if #account.update_attributes(params[:account])
format.js # Rails can also respond with JavaScript. Look up UJS. Rails 3 has made large improvements here.
format.html { redirect_to(#account, :notice => 'Account was successfully updated.') }
format.xml { head :ok }
else
format.js
format.html { render :action => "edit" }
format.xml { render :xml => #account.errors, :status => :unprocessable_entity }
end
end
end
def destroy # This results in a DELETE
#account = Account.find(params[:id])
#account.destroy # destroy is a more thourough delete and will check the options of this records associations and destroy the associated objects as well if they are dependant on this object. The option <:dependant => :destroy> is not set for this object's only association: User. The user this account belongs to will therefore survive the destruction of this account.
respond_to do |format|
format.html { redirect_to(accounts_url) }
format.xml { head :ok }
end
end
end
View
Hopefully you can draw your own logic from here. The view is designed to render information passed as instance vars from a controller to a client: browser, api, smart phone. As well as to pass information from a client to the controller via the params hash. No complicated logic should get performed in a view even though a view with erb has the capability to execute any ruby code.
If an example view would also be helpful I am happy to oblige.
The best description of what the controller is:
http://edgeguides.rubyonrails.org/action_controller_overview.html
http://edgeguides.rubyonrails.org/routing.html
The controller doesn't communicate with the Database. The controller talks to the model, which then communicate with the database.
When I was starting I found very useful to use scaffolding and just looking at what was created.
Do this:
rails generate scaffold Post name:string title:string content:text
Examine all files under the app/ folder. Examine the file config/routes
Then comment here your specific questions.
At first, I thought this question was far too broad, along the lines of "how do I program?" But after reading your comments, I see what you're getting at. You don't quite grasp how MVC works in Rails and are wondering where your code goes.
What you should strive for is a Skinny Controller and a Fat Model. Keep logic out of views. So in your example, you calculate the account balance in the Model, and pass that information along (using the controller) to the view.
For a concise explanation for beginners with sample code, I recommend this article over here.
I need to display error message on model in rails,
my coding on model is like this,
if my_address.valid?
# I need here the validation error.
return nil
end
I used errors.add("Invalid address") but it is not working
please help to solve this problem ,
You will be able to access the errors via object.errors, i.e. for your case my_address.errors. It will return Error objects, you can check up on it here: http://api.rubyonrails.org/classes/ActiveRecord/Errors.html
I suggest taking a look at how scaffolds (script/generate scaffold my_model) displays validation errors.
Here's a short summary:
def create
#post = Post.new(params[:post])
if #post.save # .save checks .valid?
# Do stuff on successful save
else
render :action => "new"
end
end
In the "new" view, you'll use #post.errors, most likely with <%= error_messages_for :post %>.