How to set-up jquery-ui autocomplete in Rails

Question

I need some help on how to implement a jquery-ui autocomplete in my Rails app.

I want to add autocompletion to a text field where the user can enter in a customer name. As there can be hundreds of customers, I will need to pull the suggested auto-completion values 'remotely', as in, from a table (at least this is what I understand).

The main point I am failing to understand is how to provide the suggested values to the autocompletion textbox. I have read the jquery-ui docs, but I seem to be a bit dense on this matter.

So what I am really after is an example of how I can get this to work in a Rails app, not necessarily a full description of how the javascript is built (that's what the jquery-ui team has done for me =) ).

For example, how do I prepare the data for the autocompletion, and how do I attach the autocompletion functionality to a textbox.

Answer 1

Well I never got an answer to my question above so I ended up having to figure it out for myself. I thought I should post the solution I came up with in case there are any other guys out there who are wondering the same thing.

First thing you should know is that this is my first experience with javascript, and I am just getting the hang of Rails. So by all means, feel free to edit, comment anywhere you feel I have gone wrong with this. Right or wrong at least I know that it functions the way I wanted it to.

I think the best way to show this is by example. So the following is how I got the autocomplete widget to work in my app. You can go ahead and put the following code in your app even if you don't understand what is happening, then we can go over how each part is working by example. After this you should have a grasp on how to modify it for your use or refractor it.

INCLUDE JQUERY UI IN YOUR RAILS APP.

Download a copy of the jQuery UI and place jquery-ui-1.8.2.custom.min.js inside your /public/javascript directory. Also make sure you have a copy of jQuery itself and that this is also in the same folder.

Include the jQuery UI file and the jQuery file in your application.html.erb file like this.
(you can name the files as you please as long as they match)

<%= javascript_include_tag 'jquery.min', 'jquery-ui-1.8.2.custom.min.js' %>

In your download of jQuery UI, you will have a folder that contains all of your CSS data. The name will vary based on the theme you chose, for example I chose the theme 'cupertino'. Place the entire folder containing your CSS data into '/public/stylesheets/'. Then include the CSS file in your application.html.erb like this.

<%= stylesheet_link_tag 'cupertino/jquery-ui-1.8.2.custom' %>

EXAMPLE AUTOCOMPLETE JAVASCRIPT

Now take the following chunk of code and place it in one of your 'new' views. You can use this in any view, but realize that I have literally taken it from an existing view belonging to a controller called 'links_controller', and it is pulling data from a 'people_controller'. Hopefully you know enough about Rails to work out what you need to change so this works for you.

-- Begin big chunk of code --

    <script type="text/javascript">
    $(function() {

 // Below is the name of the textfield that will be autocomplete    
    $('#select_origin').autocomplete({
 // This shows the min length of charcters that must be typed before the autocomplete looks for a match.
            minLength: 2,
 // This is the source of the auocomplete suggestions. In this case a list of names from the people controller, in JSON format.
            source: '<%= people_path(:json) %>',
  // This updates the textfield when you move the updown the suggestions list, with your keyboard. In our case it will reflect the same value that you see in the suggestions which is the person.given_name.
            focus: function(event, ui) {
                $('#select_origin').val(ui.item.person.given_name);
                return false;
            },
 // Once a value in the drop down list is selected, do the following:
            select: function(event, ui) {
 // place the person.given_name value into the textfield called 'select_origin'...
                $('#select_origin').val(ui.item.person.given_name);
 // and place the person.id into the hidden textfield called 'link_origin_id'. 
        $('#link_origin_id').val(ui.item.person.id);
                return false;
            }
        })
 // The below code is straight from the jQuery example. It formats what data is displayed in the dropdown box, and can be customized.
        .data( "autocomplete" )._renderItem = function( ul, item ) {
            return $( "<li></li>" )
                .data( "item.autocomplete", item )
 // For now which just want to show the person.given_name in the list.
                .append( "<a>" + item.person.given_name + "</a>" )
                .appendTo( ul );
        };
    });
    </script>



<h1>New link</h1>

<% form_for(@link) do |f| %>
  <%= f.error_messages %>

<!-- Place the following text fields in your form, the names are not important. What is important is that they match the names in your javascript above -->
  <p>
        Select which person you want to link:<br /> 
<!-- This is the textfield that will autocomplete. What is displayed here is for the user to see but the data will not go anywhere -->
        <input id="select_origin"/>
<!-- This is the hidden textfield that will be given the Persons ID based on who is selected. This value will be sent as a parameter -->
      <input id="link_origin_id" name="link[origin_id]" type="hidden"/>
  </p>
<!-- end of notes -->
  <p>
    <%= f.label :rcvd_id %><br />
    <%= f.text_field :rcvd_id %>
  </p>
  <p>
    <%= f.label :link_type %><br />
    <%= f.text_field :link_type %>
  </p>
  <p>
    <%= f.label :summary %><br />
    <%= f.text_area :summary %>
  </p>
  <p>
    <%= f.label :active %><br />
    <%= f.check_box :active %>
  </p>
  <p>
    <%= f.submit 'Create' %>
  </p>
<% end %>

-- End Big Chunk of Code --

Okay now to connect the dots.

PROVIDE DATA FOR AUTOCOMPLETE TO USE AS SUGGESTIONS

Lets start by connecting up some data that the autocomplete textfield can display in the drop down suggestions. The format we will be using is JSON, but don't worry if you are not familiar with it ... neither am I =). It is good enough to know that it is a way to format text so that other parts of yours/other applications can use it.

The data the textfield will need for the autocomplete is specified in the 'source:' option. Because we want to send a list of peoples names and their ID to the autocomplete we will put the following as the source.

source: '<%= people_path(:json) %>'  

The rails helper above will translate to a string "/people.json". You do not need to create a page at "/people.json". What you do need to do is tell your people_controller what to do when it receives a request for /people with the .json format. Put the following into your people_controller:

def index  
# I will explain this part in a moment.
  if params[:term]
    @people = Person.find(:all,:conditions => ['given_name LIKE ?', "#{params[:term]}%"])
  else
    @people = Person.all
  end

  respond_to do |format|  
    format.html # index.html.erb  
# Here is where you can specify how to handle the request for "/people.json"
    format.json { render :json => @people.to_json }
    end
end

Now we have all the people in @people being sent to the autocomplete textfield. This brings up the very next point.

FILTER DATA USED FOR AUTOCOMPLETE SUGGESTION, BASED ON INPUT

How does the autocomplete textfield know how to filter the results based on what you type?

The autocomplete widget assigned to the textfield will send whatever you type into the textfield as a parameter to your source:. The parameter being sent is "term". So if you were to type "Joe" into the textfield, we would be doing the following:

/people.json?term=joe

That is why we have the following in the controller:

# If the autocomplete is used, it will send a parameter 'term', so we catch that here
    if params[:term]
# Then we limit the number of records assigned to @people, by using the term value as a filter.
      @people = Person.find(:all,:conditions => ['given_name LIKE ?', "#{params[:term]}%"])
# In my example, I still need to access all records when I first render the page, so for normal use I assign all. This has nothing to do with the autocomplete, just showing you how I used it in my situation.
    else
      @people = Person.all
    end

Now that we have limited the number of records assigned to @people based on what is typed into the autocomplete textfield, we can now turn that into JSON format for the autocomplete suggestions.

respond_to do |format|  
      format.html # index.html.erb  
      format.json { render :json => @people.to_json }
    end 

Now, just review the comments inside the "Big Chunk of Code" which should explain the rest of how this ties together.

At the end you should have a textfield on your page that acts as the autocomplete and a hidden field that will send the ID in a parameter to your controller.

CUSTOMIZE YOUR OWN AUTOCOMPLETE

Once you understand the above and you want to modify it for your use, you should know that the format JSON returned from your controller looks like this:

[{"person":{"id":1,"given_name":"joe","middle_name":"smith","family_name":"jones","nationality":"australian"}}]

The way to access the different values from the JSON string in your javascript in this case would be:

ui.item.person.name_of_some_attribute_such_as_given_name

Pretty, simple. A lot like accessing an ActiveRecord attribute in Rails.

One last note. I spent a lot of time looking for a different way to supply the hidden value, as I thought this function should have been built into the jquery widget. However, this is not the case. It is clearly shown in the official jQuery example that the way to send a different value then selected as a parameter, is to use a hidden field.

Well I hope that helps somebody.

Dale