I've been stuck on this problem for days. First off, I now know this code is horribly wrong. I've been trying to fix it, but it's way more important in the short term that this link is created. In my view (I'm so sorry), I call the create method like this, if a certain condition is met:
index.html.erb (controller: subjects_controller)
<%= Baseline.create(subject_id: sub.subject_id) %>
I do this several times on the page, from several controllers (i.e., FollowUp3Week.create(subject_id: sub.subject_id) works). All of the other controllers work. I've checked, and double checked, every controller action and compared them to each other, and they appear the same.
So instead of creating the record, it leaves something like this instead:
#<Baseline:0x007f944c4f7f80>
I'm at a bit of a trouble shooting loss. Once again, I know how wrong it is to have these database actions in the view. But I didn't know that when I made the page, and I really need this to function before I can take the time to learn how to rearrange everything through the MVC.
Any advice would be greatly appreciated. Let me know what other code you might want to look at.
EDIT 1.
link Creation:
<% if Baseline.where(subject_id: sub.subject_id).first != nil %>
<%= link_to "edit", baseline_path(Baseline.where(subject_id: sub.subject_id).first) %>
<% else %>
<%= Baseline.create(subject_id: sub.subject_id) %>
<% end %>
First of all, making DB calls in views is a big NO! NO!
Secondly, to answer why you see the output as
#<Baseline:0x007f944c4f7f80>
for
<%= Baseline.create(subject_id: sub.subject_id) %>
You are trying to render an instance of Baseline model. Its just how the instance would be displayed. If you want to display a particular attribute's value in view then just do
<%= Baseline.create(subject_id: sub.subject_id).subject_id %>
Also, this code will not create a link. To create a link you would have to call link_to helper in your view.
What you need to do is, move the Baseline.create call in the controller. Set an instance variable in the action which renders this particular view as below:
def action_name
#baseline = Baseline.create(subject_id: sub.subject_id)
end
After this in you view you can easily access all the attributes of #baseline instance.
For example:
To access subject_id
<%= #baseline.subject_id %>
To create a link for show page of #baseline, provided you have a RESTful route to show action for baselines
<%= link_to "Some Link", #baseline %>
Related
I'm currently going through Michael Hartl's railstutorial.org, and have run into a question that Google/Stackoverflow don't seem to be answering: The tutorial has us display user information in the view by putting <%= #user.name %>, <%= #user.email %> in show.html.erb. In the controller, it has us define a show method: #user = User.find(params[:id]).
I understand why this works, but what I don't understand is why the following code does not produce the same result (I removed the show method from the controller and tried to place all the code in the view). These are my editions to show.html.erb:
<%= #user.find(params[:id]).name %>, <%= #user.find(params[:id]).email %>
It returns "undefined method `find' for nil:NilClass".
I'm sure you understand by now from the other answers and probably the tutorial that you should not have this logic in the view, HOWEVER, to answer your question:
The reason why <%= #user.find(params[:id]).name %> generates the error
undefined method 'find' for nil:NilClass is because #user is an instance variable which you deleted from the show method in the controller. So now, #user is nil and doesn't exist. Also, when you want to query the database you must use the class (model) name which is User instead of #user.
So whiles its bad practice to do this, if you wanted to, you could do <%= User.find(params[:id]).name %> (as long as its a correct id) and that would work. Your params are available in the view as they are in the controller too.
Finally, if you intend to use the show view, you cannot completely delete the show method, you must have at least:
def show
end
in order for it to work.
params is probably not available in the view, and it shouldn't.
Your problem is the main reason why you should do your data preparation in the controller: to catch issues with the data. That's the reason a controller exists.
Your code would make two requests to the database instead of one, if it wouldn't be for rails side query caching.
Prepare your #user in the controller and access it in the view. It will make testing and refactoring your code way easier and greatly improve readability.
Compare
<%= User.find(params[:id]).name %>, <%= User.find(params[:id]).email %>
VS.
<%= #user.name %>, <%= #user.email %>
You really shouldn't have a lot of logic in the views, but I think the code you are looking for is:
<%= User.find(params[:id]).name %>, <%= User.find(params[:id]).email %>
Messages are displayed green if sent by the current user, and blue otherwise. Following Rails convention, where does that logic belong?
Introdution
The user will visit /group/:id to see the list of messages, so the corresponding view is views/groups/show.html.erb and the corresponding controller is controllers/groups_controller.rb.
The message we want to display are in an array in #group, as #group.messages. The array is sorted by timestamp.
The code to style the color of the message is not important, but for simplicity purposes we will say there are two class selectors (one for from and one for to) and we can simply add a class attribute to the div that a message is within to change its color.
Both the user's sent and received messages are held in the array #group.messages.
If we have an individual message stored in message, we can test if it was sent by the current user with:
if session[:user_id] == message.user_id
Problem
Messages are ordered by timestamp and will need to be displayed in that order. For this reason, I can't see any clean way of handling the logic in the controller.
I would like to keep as much logic as possible out of the views and especially out of the partials, but after considering the options for rendering sent and received messages in different ways, the cleanest option I've found is to put the logic in the message partial.
Handling the logic in the message partial:
<% if message.user.id == session[:user_id] %>
<div class="to">
<p> <%= message.body %> </p>
</div>
<% else %>
<div class="from">
<p> <%= message.body %> </p>
</div>
<% end %>
Pros:
This method handles the logic with one if statement that is clean and simple
It allows us to make the code DRY because we won't have to use the logic anywhere else if we want it on other pages
Since every message only has a body, we don't have to make another partial to display messages without this formatting
Cons:
The logic is in the partial! I think people I'm working with or other programmers or even myself would first look in the controller then in the view then in the partial to make any changes or see the code
This doesn't feel like normal Rails convention
Handling the logic in the view:
Possibly two clean solutions -
1) Style the messages inside the logic or
2) Render a different partial for sent/received messages
Styling inside the logic:
<% #group.messages.each do |message| %>
<% if message.user.id == session[:user_id] %>
<div class="to">
<p> message.body </p>
</div>
<% else %>
<div class="from">
<p> message.body </p>
</div>
<% end %>
<% end %>
Rendering different partials:
<% #group.messages.each do |message| %>
<% if message.user.id == session[:user_id] %>
<%= render :partial => '/messages/sent_message', :message => message %>
<% else %>
<%= render :partial => '/messages/received_message', :message => message %>
<% end %>
<% end %>
Pros:
Either view solution keeps the logic out of the partial
It makes sense that showing something as one color or another is decided in the view
The view solution using two partials is clean and allows us to avoid styling within logic which also means that we can change the style within the partials and affect the look of messages everywhere.
Cons:
Both view options mean that our code is no longer DRY. Using these methods will mean that if we want the same functionality on 3 other pages, we will have to write the same code 3 more times
It makes sense that a view shouldn't be deciding anything
The view solution using two partials means that we will crowd the views/messages folder with partials, and still not have a default partial for rendering messages
Both of the view solutions just feel dirty in my opinion
My main points about my solutions -
No option allows for the logic to be held within the controller
Placing the logic inside the view means that to provide the same functionality on multiple pages, the same code will be written in more than one place
The option that looks the cleanest and makes the most sense to me means putting logic inside a partial, and there must be a better way.. right?
None of the solutions seem like they follow Rails convention
Which of the three options I coded best follow Rails convention?
Is it possible to place the logic in the controller?
Is there a better way to design this so that there is a clear solution following Rails convention?
What you probably have realized is that each of the three versions you described is either not DRY or not scalable. You've done a great job analyzing pros and cons of each option, so there is very little for me to add there. :)
To add presentation functionality to your models, Rails community uses Presenters. There is a great article on Presenters here that explains more about them.
Basically, you'll want to have one partial for message:
<div class=<%=#presenter.css_class%>>
<p> <%= message.body %> </p>
</div>
Then Presenter:
class MessagesPresenter
def initialize(message, current_user)
#message = message
#current_user = current_user
end
def css_class
message.user == current_user ? 'to' : 'from'
end
private
attr_reader :message, :current_user
end
And controller:
#presenter = MessagesPresenter.new(#message, current_user)
Voila! The presenter is available in both views and partials and is a great place to stash all presentation logic.
Since the only difference in these examples in the CSS class, you're repeating yourself quite a bit. Can't you add or remove a class on the tag depending on whether the tag belongs to the current_user or not?
This is really a presentation issue, and you can handle this simple logic for displaying the correct CSS tag using decorators (http://johnotander.com/rails/2014/03/07/decorators-on-rails/). I recommend using Draper (https://github.com/drapergem/draper).
First, for simplicity, add a current_user helper method to application_controller.rb to return the authenticated user.
Add a Decorator:
MessageDecorator.rb
def recipient_class
user_id == current_user.id ? "to" : "from" # (user_id delegates to message object)
end
Now your views can have much cleaner logic
Views
Message Partial:
<div class="<%= message.recipient_class %>">
<p><%= message.body %></p>
</div>
collection partial in the main view:
<%= render partial: "message", collection: #messages, as: :message %>
Finally, call decorate on messages in your controller action:
#messages = #group.messages.decorate
EDIT
You can also use a simple helper method rather than a decorator:
def css_class_for_message(message)
message.user_id == current_user.id ? "to" : "from"
end
In Rails, I have a "notifications" class, one field of which is "link". The links contained within this class are formatted like: exchange_path(6), where that is the path to the show action in the exchange controller.
I'm now trying to output this link as such:
<%= link_to "View Exchange", notification.link %>
This line is in a loop which begins as such:
<% #notifications.each do |notification| %>
When I click this link, it takes me to localhost:3000/users/exchange_path(6) instead of localhost:3000/exchanges/6 like I would expect. (The loop generating the faulty link is on localhost:3000/users/2)
this could be scary...
<%= link_to "View Exchange", eval(notification.link) %>
should evaluate and use the path helpers. but you need to be 100% sure that nothing bad gets put in the link field..
You could do this:
<%= link_to("View Exchange", "/#{notification.link.gsub('(', '/').gsub(')', '').gsub('_path', 's')}") %>
or set up a method in your model that formats it for you:
def format_link
link.gsub('(', '/').gsub(')', '').gsub('_path', 's')
end
and just call that in your link_to:
link_to("View Exchanges", notification.format_link)
This will only work if all the links are formatted exactly as the example in the question
When calling all posts for a user Posts.find(creator: current_user:_id), and the user hasn't made any...rails spits a "NoMethodError" for it...
What I want to do is have a pretty output for the user of "Why, no. You haven't posted anything, you lazy slob." instead of this scary error.
What's the best way to handle things like this?
You need to use where instead of find. By design, find method expect to actually find an existing thing you're looking for. Consult docs about querying here.
Also, you can try and use try method. Basically it's equal to the following:
object.try(:something_scary)
# is equal to
object && object.something_scary
This is how I handle nil entities. If you want to show some kind of message to user (about being slobby) you make a check inside of your template and render different partials. Example:
<% if #posts.present? %>
<%= render 'posts' %>
<% else %>
<%= render 'no_posts' %>
<% end %>
Then you can put your message inside of that no_posts partial.
I'm working on a small picture application. That I'm trying to do is build a counter to track how many times each image is clicked.
Right now I have in my view:
<% #galleries.each do |g| %>
<% for image in g.images %>
<div id="picture">
<%= render 'top_nav'%>
<%= link_to g.source, :target => true do %>
<%= image_tag image.file_url(:preview) %>
<% g.vote %>
<% end %>
<%= will_paginate(#galleries, :next_label => "Forward", :previous_label => "Previous") %>
</div>
Obviously this doesn't work, as the g.vote executes every time it's rendered, not clicked. Here's the vote method in my model:
def vote
self.increment!(:score)
end
I'm looking for a solution to run the vote method only when the image above is clicked. The links are to external resources only, not to a show action. Should I be building a controller action that's accepts a post, executes the vote, then redirects to the source?
Anyway, looking for some ideas, thanks.
I've done something similar, but keeping a count of how many times a Download link was clicked. This was awhile ago and I didn't know about Ajax at the time, but now I would recommend using jQuery (a great library in my opinion, but you could use something else) and do an Ajax call when the image is clicked that would execute some controller action which would increment that vote.
The other way, which is what I did in my scenario, and is what you talked about there, is creating a custom action in the controller that accepts a post. But I have to ask as well, does clicking on the image do something else in the behaviour of your website? For example, if when you click the picture, another random image is supposed to come up, that means you'll already have an action to load a new image and it be easy to stick the vote up in there before showing a new image. Otherwise you'd have to create the new controller action. If that's the case, the Ajax would be more efficient as the user wouldn't see a momentary flash as the page was refreshed (especially bad if the refresh time is long).