General ways to create a filterable search

Rails
1

Ive done a lot of searching on this and found lots of topics on what
search tools to use but couldnt find something re: how you generally
implement search into your project regardless of the choice of tool
(ferret etc).

I want users to be able to do a basic search and if they want supply
some extra conditions. I return the results and the user can further
filter those results by checking boxes, entering min max values etc. The
results are filtered instantly as happens instantly via ajax like
kayak.com without reloading the page(great site for airtickets by the
way) does. Im just wondering generally how i go about this. As you will
find out I dont have the vaguest of ideas on how.

Assuming i have a products model

Do I create a search model with no db attached (im expecting a lot of
searches and encouraging users to use the refine function - i dont
expect saving searches to be useful as per a railscast i saw)? within
this i create some methods such as (excuse the semi pseudo code cant
remember exact syntax)

class Search

def self.search(some_conditions)
Product.find(:all with some_conditions)
end

end

I assume ill have a form_tag for my search field and optional condition
fields. This will be on my products index view.

Where should the form_tag url link to? To products controller? cretae a
search method over there?

##Products controller
def search
@search_results_of_products = Search.search(params[:search_query]
end

What about when i wnat users to be able refine the results even further.
Do I need to another form for this use? Would it link back to the search
function i defined earlier and ammend the code or would i create a new
method called refine? Would I basically just hit the db again but with
the new “more refined” terms or do I use ruby to just get rid of the
unwanted results from the ones i found previously.

Lots of questions. Im sorry. If you know of a good primer on this Id be
greatful. Id like to see how code is organised.

2

You are asking about some basic programming issues, so this is
targeted that way.

You will do well to implement session variables here. You will need to
capture the user’s selected options in the session and reflect those
choices back to the form when the page is redrawn. You can use the
same form as the original search. You can have separate session
variables for each parameter or collect them in a hash. It may be
easier to work with separate variables, depending on your experience.

Use whatever controller you want to analyze the selected options and
build or select which query to use.

For those who have never done this, suppose one of the options was an
integer for size. You would pass params[:option_a] or params[:search]
[:option_a] to your controller. In the target action, you would set:

 # setting a session variable from form input; since all

parameters are of the form string,
# you need to convert it if you want an integer. This is done for
illustrative purposes here,
# as a string data type could just as well be used in the
database unless you were doing some math
# operation in the database. If you were passing an id, you would
need
# to make sure it was an integer when passed to the query
session[:option_a] = params[:search][:option_a].to_i

Then you would run the appropriate query such as:

 # using '?' makes SQL injection attacks more difficult
 @filter = Product.find_by_sql(["SELECT * FROM products WHERE

size=?",session[:option_a]])

In the view containing the form, you would make session[:option_a]
available to the appropriate input:

<% size = ‘’
unless nil == session[:option_a]
size = session[:option_a].to_s # it would typically work here
without the conversion method
end %>
<input type=text name=‘option_a’ value=<%= size -%> > …or the
rails form_helper equivalent.

This allows you to use the same form and to remember the previous
input through each iteration.

You will also want to be familiar with input validation techniques to
handle mistakes and input from users who might try to use your site in
unintended ways. You will need to use HTMLEntities for text values,
even if you use an option list to submit data:

 def search_me
 # the name for the session variable and the parameter don't have

to match, but it makes programming easier
session[:color] => HTMLEntities.encode_entities(params[:product]
[:color], :basic, :named)
…code
end

and in the form:

<% user_text = ‘’
unless nil == session[:color]
user_text = HTMLEntities.decode_entities(session[:color])
end %>
… etc

You can define searches in your model or controller (or view), but
searches should be called from the controller. If you try to define a
search in the model using session[:option_a], it will not work.

model
self.find_tea_and_crumpets(flavor)

controller
def breakfast
find_tea_and_crumpets(session[:flavor])

This does not answer all your questions, but maybe will help someone.

One of the big problems for programmers new to the MVC model is “what
goes where?”. There are various opinions, but much of it is up to you.
As you experiment, you will need tools to expose the state of your
application and what variables are being passed. To make the most of
the framework, you will need to follow rails idioms as closely as
possible, but it is not always possible with complex scenarios.

You can view the form variables being passed in the logger and you can
use session/console to test your queries. Here is a handy accessory
for this type of work:

http://snippets.dzone.com/posts/show/697

There is also the TextMate Footnotes plugin. Either of these may
require some ‘advanced’ tinkering to work satisfactorily.

You should also be familiar with logger.debug(). There is a RailsCast
on using bindings with logger.debug - very handy.

If there are any advanced programmers reading this, please feel free
to offer corrections or better ideas.

On Apr 4, 3:07 am, Adam A. [email protected]