Conditionally setting CSS style from ruby controller

Question

I'm trying to dynamically change (if it got clicked) a normal table header (which is a link) to another defined CSS class 'th.hilite'. This link simply sorts this column and the header should got highlighted every time a user sorts the list.

The view where the class in question should be changed, looks like this:

%table#mytable
  %thead
    %tr
      %th= link_to 'Title', mytable_path(:sort => 'title'), :id => 'title_header'

My question is simply: How and where could I dynamically set the class to %th.hilite if the header is clicked?

You don't have to and shouldn't use JavaScript to do this. Besides that you ought do the SaaS homework #2 by yourself. Note: The presented answer is correct. — katox
– katox, Commented Mar 10, 2012 at 19:41
You should not be posting questions directly from the saas-class.org homework 2 assignment here. You should be asking how to do something.. but not for the exact answer to your question. — Ilan
– Ilan, Commented Mar 10, 2012 at 22:01
Most importantly you should NOT have posted the code above that directly shows how to answer part of the question. Its just bad behaviour. — Ilan
– Ilan, Commented Mar 10, 2012 at 22:29
It's pretty disappointing that when I search for information about conditional rendering in haml that this is the first link on google. Everyone who signed up for that course agreed to the honour code, it's just a shame that some people don't have any personal honour anymore. — starskythehutch
– starskythehutch, Commented Jun 5, 2012 at 15:18

Szilard Muzsi · Accepted Answer · 2012-03-10 18:00:00Z

26

You can bind it from the view directly:

%th{:class => ("hilite" if @sort == "title")}= link_to 'Movie Title'...

However, you will also have to declare the @sort instance variable in your controller, and set it to either title or release, according to which column you are sorting. (i.e. @sort = params[:sort])

answered Mar 10, 2012 at 18:00

Szilard Muzsi

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1 Comment

wadkar Over a year ago

actually you dont have to declare an instance variable, you can simply use params[:sort]

krethika · Accepted Answer · 2012-08-07 21:03:04Z

14

Be careful not to put logic (even conditionals) in your views if you can find a way around it. In order to avoid this common mistake, you need to make good use of the params and session hashes and set appropriate variables in controllers

# In your view
%th{:class => @title_header}= link_to 'Title', my_path(:sort => 'title'), :id => 'title_header'

# In your controller
sort = params[:sort] || session[:sort]
if sort == 'title'
  ordering = {:order => :title}
end

edited Aug 7, 2012 at 21:03

answered Aug 7, 2012 at 3:24

krethika

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2 Comments

krethika Over a year ago

If you are wondering why the ||session[:sort], it is because you may click on something other than a sortable column, in which case you do not want sorting to become undone because your params hash has expired. You will also need a little logic in controller like "if params[:sort] != session[:sort] then session[:sort] = sort" type of thing

Alisso Over a year ago

I'm trying to understand this answer. Where in the docs can I read about "what?" to understand how the title_header can have different values for each th?

webstranger · Accepted Answer · 2012-03-12 03:30:41Z

3

BTW as long as values of your param match column name - no need to code each one

def index
    @by=params[:by]
    @movies = Movie.order(params[:by]).all
  end

answered Mar 12, 2012 at 3:30

webstranger

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Comments

Andrew Barber · Accepted Answer · 2012-09-27 02:20:19Z

3

Javascript or jquery is not required..

The following HAML will work

%th{:class=>('title' == @sortby)?'hilite':""}= link_to  'Movie Title', movies_path(:sort => 'title'), :id => 'title_header'

edited Sep 27, 2012 at 2:20

Andrew Barber

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answered Aug 4, 2012 at 2:47

user1575511

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Comments

Ximik · Accepted Answer · 2012-03-10 13:30:06Z

-2

You should use JavaScript to do this. I think it's good idea for you to use jQuery instead of pure JavaScript. Here are some examples

http://api.jquery.com/click/

http://api.jquery.com/css/

answered Mar 10, 2012 at 13:30

Ximik

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1 Comment

jjeaton Over a year ago

Neither JavaScript nor jQuery is required for this.

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