when I render an partial for my model I'm using:
<%= partial #my_model %>
Automatically it looks for the file ..view/my_models/_my_model.html.erb
I really like this notation because it feels the right way!
My Problem:
Now I want a notation to automatically look up for the edit partial.
Is there a way? Until now I used
<%= partial 'edit' %>
This is ok, but I have a lot of subclasses for my model and I liked the way that it automatically looks up in the right subclasses view folder for the template.
Until know I have to look for the class for my model and then call
<% if #my_model.class == FirstSubClass %>
<%= partial 'firstsubclasses/_edit.html.erb' %>
<% elsif #my_model.class == SecondSubClass %>
<%= partial 'secondsubclasses/_edit.html.erb' %>
<% end %>
I prefer one line :) Any ideas?
Try:
<%= partial '#{#my_model.class.name.tableize}/_edit.html.erb' %>
tableize is a method of ActiveSupport::Inflector, which includes some other cool naming manipulation methods.
Related
I am new to caching and I'm not sure what my best course of action is.
I want to cache a part of my view that relies on a complex query. The query looks something like:
#sessions_next_week = group_by_wday(LittleClassSession.location_only([1,2]).age_range_only(age_from, age_to).supports_dropins_only(support).approved_users_only.next_week)
Above you'll see a number of scopes and methods called. The view renders an instance variable named #sessions_next_week like so:
<% #sessions_next_week.each do |wday, lcs| %>
<h3><%= wday %></h3>
<%= render partial: 'table_head' %>
<% lcs.each do |s| %>
<%= render partial: 'table_row', :locals => {:s => s, :show_day => true} %>
<% end %>
<%= render partial: 'table_foot' %>
<% end %>
As you can see, #sessions_next_week is iterated through, and its children are iterated through. Given this, and given the nature of the query results in the instance variable, I'm not sure where to implement the caching. In the model? In the view?
So my questions are:
Do I need model caching or can I do this in the view?
What's the correct implementation?
The solution is to simply add two character:
#sessions_next_week ||= group_by_wday(LittleClassSession.location_only([1,2]).age_range_only(age_from, age_to).supports_dropins_only(support).approved_users_only.next_week)
This is called memoization, and you can look it up. Here's one source: http://www.justinweiss.com/articles/4-simple-memoization-patterns-in-ruby-and-one-gem/
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 have a resource called Exercises in my application. I currently have a partial called _exercise.html.erb that I use to render them. I have an outlying case where I'd like to render them in a much different way. Can I make another partial for exercises that has this other format and still be able to use <%= render #exercises %>?
If not what is the best approach? Should I out a variable in the controller that tells the partial which layout to use, this would have both layout in one file and one if to decide. Or is there some better way?
If you'd like to use business logic to determine when to show what partial for your #exercises collection you should use the to_partial_path method in the Exercise model to define that. See #4 in this post: http://blog.plataformatec.com.br/2012/01/my-five-favorite-hidden-features-in-rails-3-2/
Or, if this is more of a view-related decision (i.e. one view will always use the regular _exercises.html.erb and another view would always use e.g. _alternate_exercises.html.erb) then you can specify as such:
<%= render partial: 'alternate_exercises', collection: #exercises, as: :exercise %>
This will render the _alternate_exercises.html.erb partial once for each item in #execrises passing the item in to the partial via a local_assign called exercise.
In this case, I suppose you have two options:
1) Put the conditional code inside of _exercises.html.erb
eg.
<% if #exercise.meets_some_condition %>
you see this stuff
<% else %>
you see other stuff
<% end %>
This way, you can still make use of <%= render #exercises %>
2) Otherwise, your other option is to have separate partials and render them outside.
eg.
<% #exercises.each do |exercise| %>
<% if exercise.meets_some_condition %>
<%= render "exercises/some_condition_exercise" %>
<% else %>
<%= render "exercises/exercise" %>
<% end %>
<% end %>
This is the best approach for rendering partial. You can wrap that partial with if else statement in your code. Here is my example
rendering with form called _victim.html.erb
<%= render :partial => "victim", :locals => {:f => f }%>
rendering without form
<%= render :partial => "victim"%>
I have a partial that I'm rendering twice on the same page, but in two different locations (one is shown during standard layout, one is shown during mobile/tablet layout).
The partial is rendered exactly the same in both places, so I'd like to speed it up by storing it as a variable if possible; the partial makes an API call each time, and the 2nd call is completely unnecessary since it's a duplicate of the first API call.
Is there any way to store the HTML from the returned partial as a variable and then use that for both renders?
Edit: I'm hoping to do this without caching, as it is a very simple need and I'm looking to keep the codebase lean and readable. Is it possible to store the partial as a string variable and then reference that twice?
<% content_for :example do %>
<%= render :your_partial %>
<%end%>
then call <%= yield :example %> or <%= content_for :example %> wherever you want your partial called.
One option would be to use fragment caching. After you wrap the partial with a cache block, the second call should show the cached version of the first. For example:
<% cache do %>
<%= render(:partial => 'my_partial') %>
<% end %>
... later in the same view ...
<% cache do %>
<%= render(:partial => 'my_partial') %>
<% end %>
To store the result of the render to a string, you could try the render_to_string method of AbstractController. The arguments are the same as for render.
partial_string = render_to_string(:partial => 'my_partial')
I'm adding an answer to this old question because it topped Google for a search I just made.
There's another way to do this now (for quite a while), the capture helper.
<% reuse_my_partial = capture do %>
<%= render partial: "your_partial" %>
<% end %>
<div class="visible-on-desktop"
<%= reuse_my_partial %>
</div>
<div class="visible-on-mobile"
<%= reuse_my_partial %>
</div>
This is simpler and slightly safer than using content_for because there is no global storage involved that something else might modify.
The rails docs linked to use instance #vars instead of local vars because they want it to be available to their layout template. That's a detail you do not need to worry about, because you're using it in the same template file.
Problem
My app manages ProjElements, which are subclassed into:
Milestone
Task
Decision
... etc
For a given ProjElement's show.html.erb, you can comment on that project element instance (e.g. you can add a comment on Milestone XYZ or Decision ABC). Like this:
// display project element specific stuff
// - e.g. show.html.erb for Milestone has milestone-specific stuff
// - e.g. show.html.erb for Decision has decision-specific stuff
// provide comment functionality
// - e.g. for Milestone's show.html.erb, code looks like
<%= form_for [#milestone, Comment.new] do |f| %>
<% if #milestone.comments.size > 0 %>
...
<% end %>
<% f.submit %>
<% end %>
Proposed approach
I plan to use a partial for the comment code and use it across the various show.html.erb views for different project elements, as per DRY. But ...
How do I write generic code for the partial, the Rails way, so that the partial can deal with different project elements?
You can pass the element's subclass instance through the locals hash. In app/views/milestones/show.html.erb
render :partial => 'shared/comments', :locals => { :element => #milestone }
In app/views/shared/_comments.html.erb
<% form_for [element, Comment.new] do |f| %>