On each text_area on my site, I have a select_box for selecting the language. It often uses certain default languages, but sometimes checks for custom options. I initially had the array setup in the controller:
#language_array = [ ["english", 1], ["french", 2], ["spanish", 3] ]
#language_array = get_custom_array if custom_language?
And it would then be accessed by the view:
<%= select_tag(:language, options_for_select(language_array, default_language) )%>
This worked fine, and the text_area would display the language and pass on the number. However, I would now like to add multiple text_areas to each page, so I moved the code into a helper, and access the helper from every text_area in the view:
language_array = get_language_array(thing.id)
<%= select_tag(:language, options_for_select(language_array, default_language) )%>
However, now the text_area comes out messed up, and displays the array instead of just the language:
["english", 1]
How can I fix it (without changing the currently stored arrays)? I also want variables from the helper to be available to javascript on the page. Is there a better way to deal with multiple "things" than to move everything from the controller to the helpers?
You could have them inside the model as a hash like this
user.rb
def User
def self.language
{
'English' => '1',
'French' => '2',
....
}
end
end
and in the controller obtain the hash into a variable and it will be accessible in both the html.erb and the js.erb
users_controller.rb
#language = User.language
Then while building the form you can do it as
<%= talent_field.select(:language, #language, {}, {:class => 'language-select'} %>
Related
I want to make an Navigation with specific Tags.
These Tags are for example: HTML, CSS and Javascript.
So when i click on one of them it will show all posts with these tag.
How can i achieve that?
My code for the Navigation right now looks like this (it's in the Application.html.erb)
<%= link_to "Computer", tag_list.Computer %>
I get this Error:
undefined local variable or method `tag_list' for #<#:0x007feec764ff88>
tag_list is a local variable or method, so unless you've created it in a helper that's your first issue. The second is that called .Computer on it doesn't work because tag_list is a method that created by the gem to list all an objects tags, and calling the . (also knowing as chaining) is attempting to call a method named Computer, which doesn't exist, that should just be a string and strings have to be quoted.
So, in your layout view, you can do
= link_to "Computer", tagged_posts_url(tag: "Computer")
Then in your posts_controller.rb add an action called tagged
def tagged
if params[:tag].present?
#posts = Post.tagged_with(params[:tag])
else
#posts = Post.all
end
end
To maintain a DRY set of views, you can even tell it to render the index view since you most likely already have a list of posts, now it will look exactly the same but only contain posts with that tag. e.g.
def tagged
if params[:tag].present?
#posts = Post.tagged_with(params[:tag])
else
#posts = Post.all
end
render "index"
end
Then in your config/routes.rb add a route for your new controller action under your existing post route
resources :posts do
collection do
get "/posts/tagged", as: :tagged
end
I got it myself.
Here is the Code:
<%= link_to 'Computer', { :controller => 'posts', :action => 'index', :tag => 'Computer'} %>
The controller looks like this:
def index
if params[:tag]
#posts = Post.tagged_with(params[:tag]).order('created_at DESC')
else
#posts = Post.all.order('created_at DESC')
end
end
This must be a common need but I can't seem to find a definitive answer on the most rubyesque way. I need to create a fairly complex algorithm to dynamically calculate course grades in a rails 4.1 app.
Specifically, I have a model, "course", and whenever an instance of it is displayed in the view, I want to dynamically calculate the current grade (a decimal value, calculated from many course.field values) and display it as a letter value using a switch/case. My assumption was that I could do this in the controller (but it almost seems like it's complex enough to warrant it's own -- module? In C++ I would create a class). At the same time, since it is created dynamically, it seemed like bad form to create a current_grade field for it in the model, so it's not one I can pass back and forth as one of the allowable params (that I know of-- can one pass a variable in the params that is not represented in the db?).
In my initial research I see suggestions of hidden_field_tags and helper_methods and all_helpers and modules and global modules and more. Under time pressure, I dread beginning down the wrong path. Which is the better approach? Or a good high level doc for reference?
As an example, here is one view in which I would like to calculate current grade, compare it to desired grade, and display accordingly.
# index.html.erb
<% #courses.each do |course| %>
<li>
<%= my_algorithm_to_calculate_curr_grade(many course.fields used to caluculate)
<= course.desired_grade ? "set li to <Color: red>" : "set li to <Color: green>" %>
<%= course.course_name %>
Current Calculation: <%= display_results_of_previous_calculation %>
(Goal: <%= course.desired_grade %>)
<%= link_to 'Show', course %>
<%= link_to 'Edit', edit_course_path(course) %>
<%= link_to 'Drop Course Without Penalty', course, method: :delete, data: { confirm: 'Are you sure?' } %>
</li>
<% end %>
It's hard to tell from your question if course.fields are attributes of Course or different model(s). If all the fields are Course attributes, I would put it as an instance method on Course.
class Course < ActiveRecord::Base
def calculated_grade
# fun algorithm
end
end
If course.fields need to be loaded from the database, I'd probably go with a Plain Old Ruby Object (PORO), maybe call it CourseGradeCalculator (put it in app/models, why not? It's business logic)
class CourseGradeCalculator
attr_reader :course, :fields, :grade
def initialize(course, fields)
#course = course
#fields = fields
#grade = calculate_grade
end
private
def calculate_grade
# fun algorithm
end
end
# controller
#course = Course.preload(:fields).find(params[:id]
# view
CourseGradeCalculator.new(#course, #course.fields)
I'm trying to have a drop down list but when i try it it give me
undefined method `collect' for nil:NilClass
the controller:
def existing
#courses = Course.all
end
def duplicate
course = Course.find_by_id(permitd_up[:id])
new_course = course.dup
if new_course.save
redirect_to :action => 'show'
else
redirect_to :back
end
end
the view:
<h3>Choose a Course</h3>
<%= form_for :course , url: {:action => "duplicate" , method: "post"} do |f|%>
<%= f.select :id , #courses.collect{|c| [c.id , c.name]} %>
<br><br>
<%= f.submit%>
<%end%>
You will receive the following error
undefined method `collect' for nil:NilClass
on
<%= f.select :id , #courses.collect{|c| [c.id , c.name]} %>
Only when #courses instance variable was not set in the action that rendered this particular view.
I see that #courses variable is set in the existing method. If you are using existing as an action which renders this view then your view name must be existing.html.erb.
Or if you are rendering the view from a different action then in that case you should set #courses value in that particular action by either directly setting the value within action OR by calling existing method from there.
If you have your courses as a database table, you might want to try using rails' built in field helper collection_select. It will populate your select field with all of the data available in your model. If you want a drop-down like the one you are describing, I believe using collection select is the best way to handle it.
You can read up on it here: http://api.rubyonrails.org/classes/ActionView/Helpers/FormOptionsHelper.html
Alternatively, if you have a ton of courses, maybe try looking into using a text field with autocomplete. Jquery UI has a plugin that makes this very easy. You can check out the railscasts for it here: http://railscasts.com/episodes/102-auto-complete-association-revised.
It requires a pro account but if you do a lot of rails developing it will be the best $9 you spend every month.
If you would like to continue to do it this way, make sure that you are defining
#courses = Courses(:all) in the correct controller action, otherwise you will have nothing to render.
i'm having a bit of trouble with adding a certain feature. i'm working on a buy/sell site and i want to be able to compare posts. here's what i have so far:
in the posts view:
<%= button_to "Add to Compare", :action => "addCompare" %>
in the corresponding controller:
##a = Array.new()
def addCompare
##a << Post.id
end
so, all i want to do is add the post's id to the array ##a. when i test this, i click on the "Add to Compare" button and I'm welcomed with this:
Template is missing
Missing template posts/addCompare with {:locale=>[:en, :en], :formats=>[:html], :handlers=>[:rxml, :rjs, :builder, :rhtml, :erb]} in view paths "/home/mja32/470repo/traders/app/views", "/var/lib/gems/1.8/gems/devise-1.4.2/app/views"
So I guess it's trying to redirect to a view. How do I prevent it from doing this? All I want this button to do is to add the post's id to the array and nothing more.
Thanks in advance,
Matt
First of all, storing persistent data in a controller's class variable isn't going to work the way you want it to. There's no guarantee that ##a will be the same array on your next addCompare call; for example, your next addCompare call could be handled by a different process. Also, what happens if two different clients call addCompare? Do you really want to mix their data together in one pile? Probably not. Your first task is to replace ##a with a real per-user persistent store.
If you want to return nothing at all from your controller, just do this at the end of your controller method:
render :nothing => true, :status => :ok
That will tell Rails that something has already been rendered so it doesn't need to try the default rendering action (which is to render the posts/addCompare view) and returns nothing more than a 200 status code to the client.
Once that's in place, you'll probably want to AJAXify your button with :remote => true:
:remote - If set to true, will allow the Unobtrusive JavaScript drivers to control the submit behaviour. By default this behaviour is an ajax submit.
So this:
<%= button_to "Add to Compare", { :action => "addCompare" }, { :remote => true } %>
Note that button_to looks like this:
button_to(name, options = {}, html_options = {})
and that :action is for options but :remote is for html_options so you have to explicitly set up the hashes with {}; you could just wrap the options in braces:
<%= button_to "Add to Compare", { :action => "addCompare" }, :remote => true %>
but I prefer the consistency of wrapping them both by hand.
It's obvious from the documentation (and google) how to generate a link with a segment e.g. podcast/5#comments. You just pass a value for :anchor to link_to.
My concern is about the much simpler task of generating the <a name="comments">Comments</a> tag i.e. the destination of the first link.
I've tried the following, and although they seemed to work, the markup was not what I expected:
link_to "Comments", :name => "comments"
link_to "Comments", :anchor => "comments"
I think I'm missing something obvious. Thanks.
You are getting confused by Ruby's syntactic sugar (which Rails uses profusely). Let me explain this briefly before answering your question.
When a ruby function takes a single parameter that is a hash:
def foo(options)
#options is a hash with parameters inside
end
You can 'forget' to put the parenthesis/brackets, and call it like this:
foo :param => value, :param2 => value
Ruby will fill out the blanks and understand that what you are trying to accomplish is this:
foo({:param => value, :param2 => value})
Now, to your question: link_to takes two optional hashes - one is called options and the other html_options. You can imagine it defined like this (this is an approximation, it is much more complex)
def link_to(name, options, html_options)
...
end
Now, if you invoke it this way:
link_to 'Comments', :name => 'Comments'
Ruby will get a little confused. It will try to "fill out the blanks" for you, but incorrectly:
link_to('Comments', {:name => 'Comments'}, {}) # incorrect
It will think that name => 'Comments' part belongs to options, not to html_options!
You have to help ruby by filling up the blanks yourself. Put all the parenthesis in place and it will behave as expected:
link_to('Comments', {}, {:name => 'Comments'}) # correct
You can actually remove the last set of brackets if you want:
link_to("Comments", {}, :name => "comments") # also correct
In order to use html_options, you must leave the first set of brackets, though. For example, you will need to do this for a link with confirmation message and name:
link_to("Comments", {:confirm => 'Sure?'}, :name => "comments")
Other rails helpers have a similar construction (i.e. form_for, collection_select) so you should learn this technique. In doubt, just add all the parenthesis.
If you want to go through rails, I suggest content_tag (docs).
Example:
content_tag(:a, 'Comments', :name => 'comments')
<%= link_to('new button', action: 'login' , class: "text-center") %>
created an anchor tag for login.html i.g
new button
and for
new button
use
<%= link_to('new button', controller: 'admin',
action: 'login' , class: "text-center") %>