I'm having trouble figuring out how to display an index.
In my organisation requests view folder, I have a file called index.html.erb.
In that file, I'm trying to list each organisation request. I've tried each of the following formulations:
<% OrganisationRequest.each do |OrgReq| %>
<% organisation_request.each do |OrgReq| %>
<% #organisation_request.each do |OrgReq| %>
<% #organisation_requests.each do |OrgReq| %>
In each case, I get an error that says:
formal argument cannot be a constant
I thought a constant meant something beginning with a capital letter. 3 of the above attempts don't begin with a capital letter.
It's also confusing to me since in my user index, I have <% User.each %> and I don't get an error message.
Can anyone see what's gone wrong? How do I ask for a list of objects?
If you have your data and view right, you should be able to fix with:
<% #organisation_requests.each do |org_req| %>
...
<% end %>
If we stick Rails conventions, we'd say that, you have a OrganisationRequests controller, has such content.
class OrganisationRequestsController < ApplicationController
...
def index
#your_local_variable = OrganisationRequest.find(...)
end
...
end
That is to say, you need to use, #your_local_variable inside view file.
<% #your_local_variable.each do |o| %>
....
<% end %>
If the variable inside index action is #organisation_requests, use that.
Related
I'm in the process of refactoring some code. I'm trying to use arrays in my view as part of a for loop that makes columns in a table.
I have defined the arrays in my controller:
subjects_controller.rb
def index
...
#CRFS_TO_VIEW = [Baseline, TreatmentCompletion]
#CRF_PATH = {Baseline => 'baseline_path', TreatmentCompletion => tc_path}
end
So my goal; as the function iterates over #CRFS_TO_VIEW, the correct path is selected from #CRF_PATH and appended to the link_to function.
indext.html.erb
<% #CRFS_TO_VIEW.each do |crf| %>
<% path = #CRF_PATH[crf] %>
<%= link_to "edit", path(crf.where(subject_id: sub.subject_id).first %>
<% end %>
I also tried :
<%= link_to "edit", #CRF_PATH[crf](crf.where(subject_id: sub.subject_id).first %>
Which didn't work. I feel I must be getting close, any help or insight would be greatly appreciated.
Thanks.
A few things:
a. You should save yourself some time and loop through the dictionary instead of the array:
<% #CRF_PATH.each do |crf, path| %>
...
<% end %>
b. You are getting a string from the loop - you can invoke the equivalent method with send:
<%= send(path, ...) %>
c. You can simplify your retrieval of the objects using:
crf.find_by(subject_id: sub.subject_id)
That said - this seems like a pretty bad way of doing things. I'd recommend instead adding a view helper:
def crf_path(crf)
case crf
when Baseline then baseline_path(crf)
...
end
With something like this you could use (notice changed the find_by to find_by! for safety as well):
<% #CRFS_TO_VIEW.each do |crf| %>
<%= link_to "edit", crf_path(crf.find_by!(subject_id: sub.subject_id) %>
<% end %>
Finally instance variables should NOT be named upper case. If you want to use a constant define it as a constant (otherwise use lower case names).
I'd like to answer what I'm doing wrong. So, I'm trying to list all products that belong to the category, on the category's page. Here is the code:
<% #product = Product.all%>
<% #product.where("category_id = ?", params[:#category_id]).each do |product| %>
<%= product.title %>
<%end%>
But there is nothing showing up on my page. So, what's wrong?
There is a whole bunch of problems with your code.
1) Read guides for starters.
2) You have to define an instance variable in controller's action, and then in view just use this variable in your loop. I assume, it is index action you have view for. If so,
def index
# this variable will be used in view
#products = Product.where(category_id: params[:id])
end
and then in view
#products.where(category_id: params[:category_id]).each..
Also, Make sure you have in params what you expect (inspect the params if not sure).
3) You do not execute code, so nothing is being output.
In erb to make things being evaluated you either use - or =. You used none of these. Here is how it should look like:
# notice dash at the beginning of the line
<%- #products.each do |product| %>
<%= product.category_id %>
<% end %>
probably you want read :category_id from params, not :#category_id (so it should be params[:category_id], not params[:#category_id]).
I want to display a random assortment of 6 tools from my database on my home page. I have created a Pages controller with a home action.
This is my Pages controller:
class PagesController < ApplicationController
def home
#tools = Tool.all
end
end
Then in my home.html.erb view I use the .sample method to grab random tools from my database as such(I repeat this 6 times using tool1, tool2, tool3, etc variables for each):
<% tool1 = #tools.sample %>
<%= image_tag tool1.tool_image.url(:medium) %>
<%= tool1.name %>
<%= tool1.description %>
I am wondering if there is a better way to do this. It seems that I have logic in my view and there must be a way to move that logic somewhere else? My model, controller, etc. How would one go about cleaning this code up so that it's good rails code? Or maybe this is good rails code and I just don't know it since I am a beginner.
Your controller doesn't need to extract everything from the tools_table, so I'd first remove the .all. Your example makes it seem like you just need 6 random objects from the database, here's one way to do that:
class PagesController < ApplicationController
def home
#tools = Tool.order("RANDOM()").first(6)
end
end
Then in your view you can just loop through those:
<% #tools.each do |tool| %>
<%= image_tag tool.tool_image.url(:medium) %>
<%= tool.name %>
<%= tool.description %>
<% end %>
In addition to Anthony's answer.
To clear up the view with some rails magic you can also add a partial to your app/views/tools called:
_tool.html.erb
Looking like:
<%= image_tag tool.tool_image.url(:medium) %>
<%= tool.name %>
<%= tool.description %>
And then change your view to
<%= render #tools %>
And Rails will know what to do if #tools is a collection of tools 😄
I'm trying to experiment with blocks and how to iterate over collections in ERB. I have a models in a one-to-many relatinship (Channel and their corresponding types).
controller
class HomePageController < ActionController
def index
#channels = Channel.all
end
end
Then in the view, I iterate over all the attributes belonging to a Channel. When I want to print all types, this code gives me the desired output:
view
<% #channels.each do |channel| %>
<% #types.each do |type| %>
<%= Type.find(type).name %>
<% end %>
<% end %>
At first I tried to achieve this by using the yield keyword in a neat one-liner but I couldn't manage to print anything to the browser, only to the console
<% #types.each {|type| yield Type.find(type).name } %>
Is there an equivalent one-liner?
First of all this method is so inefficient, you are doing n-queries, to find each record of type Type instead convert those into an array of types by using a single query in the controller, assume that that array is in type_ids
# controller
#channels = Channel.includes(:types) # avoiding n+1 queries
# view
<% #channels.each do |channel| %>
# some channel info output
<% channel.types.each do |type| %>
<%= type.name %>
<% end %> # types loop
<% end %> # channel loop
As #Almaron mentioned, you could render a partial for more simplification, if you have a partial called _type.html.erb you can call render directly
# view
<%= render channel.types %>
Rails will do all the iterating and rendering.
First of all, this kind of code does not belong to the view. Don't tackle the database from the view (in your case Type.find()). Move it to the controller where it belongs.
The second thing to note is the difference between <%= and <% tags. The first one outputs the returned result, while the second one doesn't. The problem with .each is that it returns the object it has been used on, so in your case if you just go <%= #types.each {|type| Type.find(type).name } %> you'll get the #types array printed out.
If you want to simplify that code, you can use a helper method for iterating and a partial for rendering each item. That way you get something like this
<% collection_iterate #items, 'item_partial' %>
I have an isolated issue.
I have a table that populates from several different models, it creates links to follow to each respective view.
The code that I have made for each link should be the same, but for some reason, the link isn't showing up under 'Baseline'. I've checked the :create methods for each model, and they mimic each other, and the code from the view is also just a copy - so I'm at a loss as to where to look next. I'm sure that the problem is that the create method is failing, but I don't know where/how.
Here is the code from my view (I'm also pasting the code from FollowUp3Week, because it works):
<% 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) %> #I left the equal for the screenshot.
<% end %>
</td>
<td>
<% if FollowUp3Week.where(subject_id: sub.subject_id).first != nil %>
<%= link_to "edit", follow_up3_week_path([FollowUp3Week.where(subject_id: sub.subject_id).first]) %>
<% else %>
<% FollowUp3Week.create(subject_id: sub.subject_id) %>
<% end %>
</td>
And here is the create method from baselines_controller.rb
def create
#baseline = Baseline.new(params[:baseline])
if #baseline.save
flash[:success] = "Baseline added from create method"
redirect_to baselines_url
else
render 'new'
end
end
I'm also attaching an image of what it looks like. If I remove the equal sign from <%=, the cell will be blank.
EDIT. I'm in the process of removing all of my database queries from the view. Thank you for your comments.
You should really get that Baseline.where out of your view and into the model. AR scopes from the view is a serious no-no in Rails.
In your baseline mode you could do something like:
def empty_subject(subject_id)
where(subject_id: subject_id).first != nil
end
Also, it looks like you're passing arrays into baseline_path and follow_up3_week_path.
Ditch the square brackets.
on Baseline model, put this
def display_name
"#{name}" #whatever you like to show including link
end