SciWerks.com » auto_complete http://www.sciwerks.com/blog Software for scientists, by scientists Fri, 24 Oct 2008 01:02:08 +0000 http://wordpress.org/?v=2.8.4 en hourly 1 How to use an auto_complete to validate passwords http://www.sciwerks.com/blog/2007/01/31/how-to-use-an-auto_complete-to-validate-passwords/ http://www.sciwerks.com/blog/2007/01/31/how-to-use-an-auto_complete-to-validate-passwords/#comments Thu, 01 Feb 2007 02:04:20 +0000 Kevin Olbrich http://www.sciwerks.com/blog/2007/01/31/how-to-use-an-auto_complete-to-validate-passwords/ As a follow up to my previous article about using auto_completes to ensure unique filenames, I’ve put together a bit of code that does essentially the same thing except that it checks a password field to ensure that it meets certain criteria.

  1. # view file
  2. <%= text_field_with_auto_complete :user, :password %><div id=login_error></div>
  3.  
  4. # model file
  5.  
  6. def User < ActiveRecord::Base
  7.   validates_length_of :password, :in=>3..20
  8. end
  9.  
  10. # controller file
  11.  
  12. def auto_complete_for_user_password
  13.   @user = User.new(params[:user])
  14.   @user.valid?  # ensures the errors array is populated
  15.   password_errors = @user.errors.on(‘password’)
  16.   render :update do |page|
  17.      page.replace_html ‘login_error’, (password_errors.empty? ? "" : password_errors)
  18.    end
  19. end

This will indicate when a password does not meet the validation criteria defined in the model. You can add custom validations to check the strength of the password itself.

]]> http://www.sciwerks.com/blog/2007/01/31/how-to-use-an-auto_complete-to-validate-passwords/feed/ 0 Passing extra data with an auto_complete http://www.sciwerks.com/blog/2006/11/21/passing-extra-data-with-an-auto_complete/ http://www.sciwerks.com/blog/2006/11/21/passing-extra-data-with-an-auto_complete/#comments Tue, 21 Nov 2006 19:23:43 +0000 Kevin Olbrich http://www.sciwerks.com/blog/2006/11/21/passing-extra-data-with-an-auto_complete/ I recently found myself trying to use an auto_complete field to allow the user to select an object from a list of possible objects. That’s all fine and dandy, but I wanted to exclude certain values depending on which object I was editing. There are at least two ways to do this, the first is to stuff the extra data into the session and then read that value from the auto_complete_for method and act appropriately.

I don’t really like this approach because I don’t want to clutter up the session with various form parameters. Thankfully, there is a simple way to do this by once again abusing the built in text_field_with_auto_complete function…

  1. # View
  2. <%= text_field_with_auto_complete ‘new_object’, ‘name’, { :tabindex=>1 }, {:url=>{:action=>’auto_complete_for_object_name’, :extra=>@object.extra} %>

[In my case, I used the :extra data to exclude certain objects from the auto_complete_for response]

By passing the :url option, you rewrite the URL that the AJAX actions call, enabling you to add extra parameters that can be acted on by the method. Also note that you can change the name of the action called (in fact, you need to specify it or it will default to the name of the action for the current view… probably not what you want). This is handy because it lets you assign the response to a variable with a different name without writing a separate auto_complete_for handler. In this case, the submitted form will have a ‘new_object[name]‘ in the params, even though the action called was ‘auto_complete_for_object_name’.

Needless to say, you need to write a custom ‘auto_complete_for’ method to handle the extra data. Note that you could also use this method to handle multiple auto_complete fields.

]]> http://www.sciwerks.com/blog/2006/11/21/passing-extra-data-with-an-auto_complete/feed/ 2 Using an auto_complete to ensure uniqueness http://www.sciwerks.com/blog/2006/10/09/using-an-auto_complete-to-ensure-uniqueness/ http://www.sciwerks.com/blog/2006/10/09/using-an-auto_complete-to-ensure-uniqueness/#comments Mon, 09 Oct 2006 16:33:52 +0000 Kevin Olbrich http://www.sciwerks.com/blog/2006/10/09/using-an-auto_complete-to-ensure-uniqueness/ nefarious purposes.]]> The Problem

Occasionally there is a need to have a user enter a unique string. For example, if you want to ensure that a new user’s login id is not used by someone else. The traditional rails way of doing this is to set up a ‘validates_uniqueness_of’ validation on the model and then catch the error when you try to save the record.

From the user’s point of view, this can be a horrendously painful experience that can be akin to trying to outsmart the Sphinx.

Form: “please enter a unique login id’
User: “john smith”
Form: “Wrong, guess again!”
User: “jsmith”
Form: “Nope, getting warmer”
User: “jsmith1″
Form: “You wish! Keep trying!”
User: “as;ldfkjasd;flkajsdf;lakjsd”
Form: “Ha! your id must be only numbers and letters!”
User: “!@!$!@!#!@#!@#!@#%*(#^($!!!!!!!”
Form: “Sorry, wrong again!”
* user navigates to youtube *

The biggest problem here is that there is no feedback to the user if the value they selected is valid until they submit. Some forms will also force you to retype your new password everytime this fails as well. Double ouch!

Solutions

  1. offer suggestions for valid responses when it fails the first time. Not exactly the best, you might as well autogenerate their id for them and hope they don’t forget it.
  2. provide feedback with AJAX to let them know if the value is ok.

As you might have guessed from the title of the article, I’m going to show you how to do this with a standard rails auto_complete text field.

  1. # view file
  2. <%= text_field_with_auto_complete :user, :login_id %><div id=login_error></div>
  3.  
  4. # controller file
  5.  
  6. def auto_complete_for_user_user_name
  7.   @user = User.find_by_user_name(params[:user][:user_name])
  8.    render :update do |page|
  9.      page.replace_html ‘login_error’, (@user ? "Login id already in use" : "")
  10.    end
  11. end

That’s it. Anytime the auto_complete matches a record, it will change the ‘login_error’ div to indicate there’s a problem.

Net result…. a much better user interface experience and much happier users.

]]> http://www.sciwerks.com/blog/2006/10/09/using-an-auto_complete-to-ensure-uniqueness/feed/ 6 multiple_auto_complete plugin http://www.sciwerks.com/blog/2006/09/25/multiple_auto_complete_plugin/ http://www.sciwerks.com/blog/2006/09/25/multiple_auto_complete_plugin/#comments Mon, 25 Sep 2006 17:59:45 +0000 Kevin Olbrich http://www.sciwerks.com/blog/2006/09/25/16/ Rails’ auto_complete control can be a really handy way to allow users to select an object or string from a list of pre-existing values, however, one big limitation to its use is the fact that you can’t have more than one of them on a single page.

UPDATE: just to clarify this a bit. If you have more than one auto_complete that tries to access the same model/field combo, you get into trouble. You can have multiple auto_completes so long as they access different model/field combinations.

I tried a couple of hacks around this problem (some involving method_missing), and finally found a method that works pretty well and doesn’t mess up your controllers.

The approach I ended up using was to rewrite the ‘auto_complete_for’ and ‘text_field_with_auto_complete’ functions so that they ignore trailing numbers on a dom_id. Once you install the plugin (see below), you simply use it like this…

  1. # View file
  2. <%= text_field_with_auto_complete ‘object_1′, ‘name’ %>
  3. <%= text_field_with_auto_complete ‘object_2′, ‘name’ %>

  1. # controller file
  2. auto_complete_for :object, :name

All the auto_complete fields named /object[-_]d+/ will call the ‘auto_complete_for_object_name’ function in the controller now. The default response function will pull out the correct information and respond as usual.

When you submit the form, the values will be passed in the params hash as

  1. params = { ‘object_1′ => {‘name’=>’name1′}, ‘object_2′=>{‘name’=>’name2′ }}

Installation

script/plugin install svn://sciwerks.com/home/sciwerks/public_svn/multiple_auto_complete/
]]> http://www.sciwerks.com/blog/2006/09/25/multiple_auto_complete_plugin/feed/ 7 Cascading selects vs. auto_complete http://www.sciwerks.com/blog/2006/09/13/cascading-selects-vs-auto_complete/ http://www.sciwerks.com/blog/2006/09/13/cascading-selects-vs-auto_complete/#comments Wed, 13 Sep 2006 19:41:03 +0000 Kevin Olbrich http://www.sciwerks.com/blog/2006/09/13/cascading-selects-vs-auto_complete/ I have lately come to dislike cascading selects (where the value from one select populates a second select with some values). These beasties have their purpose in life, but for the most part they are unnecessary evils.

If you have a ‘Really Long List’ to select from, then using a cascading select makes a lot of sense (unless you want your users to hate you). The problem is that they are a pain to code (well, not so bad if you use the KRJS plugin ), and they are still a pain to use if you actually know what you are looking for (then you have to remember what ‘category’ if falls in).

Lately I have been getting around this little problem using auto-complete boxes.
In Rails you can have an auto_complete box act like a select like this…

  1. # model
  2.  
  3. # id              :integer
  4. # name         :string
  5. # category_id :integer
  6. # full_name   :string
  7.  
  8. class Model < ActiveRecord::Base
  9.   belongs_to :category
  10.   validates_uniqueness_of :full_name
  11.  
  12.   def before_save
  13.     self.full_name = "#{self.category.name} – #{self.name}"
  14.   end
  15. end
  1. # Controller
  2. class ModelController < ActionController::Base
  3.  
  4.   auto_complete_for :model, :full_name
  5.  
  6.   def action
  7.     if request.post?
  8.        @model = Model.find_by_full_name(params[:model][:full_name])
  9.        # do some error handling here if item does not exist… or you could create a new one
  10.     else
  11.       @model = Model.new
  12.    end
  13.  
  14. end
  1. # view for ‘action’
  2. <%= start_form_tag :action=>’action’ %>
  3. <%= text_field_with_auto_complete ‘model’, ‘full_name’ %>
  4. <%= submit_tag ‘Submit’ %>
  5. <%= end_form_tag %>

Now when the user starts typing in the auto_complete field, they will get records that match against both the name and the category of the record. The enterprising reader could also replace certain characters (like space) with the SQL wildcard ‘%’ to get more flexible search results.

A user might be able to just type: ‘f mus’ to find ‘Ford – Mustang’.
(It’s not well known, but ‘f%mus’ will match ‘Ford – Mustang’ using the standard auto_complete box that ships with rails).

This type of entry is really fast and quite intuitive once users get the hang of it.

I find that this system works best when
1. There are a ton of choices
2. The user already has a pretty good idea which choice they want to select, but don’t really want to spend 15 minutes scrolling to find it.

It’s not particularly good if the user has no idea what to enter. In those cases, the standard cascading select may help walk them through the selection process.

Notes: You can avoid using the ‘full_name’ column if you properly design your own custom auto_complete_for function

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