Question

I have several questions regarding CI application design.

Q. When creating a new form and your using CI’s form_helper I’m creating arrays in the controller and passing it to the view/form_input() method. Should I be doing this in the controller, the view, or a separate file?

Q. In my controller, I create a method for my form i.e., new_user() and in my view/form_open() I specify a different method in my controller to handle the action (i.e., add(), edit(), delete() ..etc) & that method handles the validation. This is the way that I perfer; however, I’ve had a lot of difficulty passing the data around if the validation fails. Any suggestions?

Q. I have an instance or two that when I perform form validation I need to validate against two $_POST variables. An example would be, on validation I need to query the database to determine if the entered business already exists (based off business name and zip code) then redirect back to the view and persist the post variables. So far I haven’t been able to find a way to create a custom callback function to do this because you can only pass in one parameter. The only way that I’ve been able to get this to work is if validation passes, I then perform the database check and if the business exists I put the $_post in session/flashdata and use redirect to load the view again. The array that defines the form_input attributes calls set_value for that is where it pulls the flashdata for each record in the array.

$data['name'] = array(
    'name'     => 'name',
    'id'       =>  'name',
    'value'    =>   set_value('name', $this->session->flashdata('name')),
    'maxlength'   =>  '200',
    'size'     =>  '79',
    'class'    =>  'text'

I realize that this really comes down to preferences; however, I’m really wanting to gain some insight on what pitfalls I can expect and how others are designing their applications. I’ve downloaded sample applications and I’ve dome a good amount of searching but I really haven’t found much discussion. Any suggestions are greatly appreciated.

Thank you!

Answer 1

I’ll share my approach using CI

1. I create Controller as slim as possible. The controller main job will only get parameter through URI, _GET, and _POST. Then controller will pass required parameter to models, and get the result. After that, view file will be loaded and all variables required by the view will be passed.
2. All process logic, related with database, email sending, etc, is handled in the model. Model will get parameter, do query, process query result if needed, then return an array, resultset, boolean, or integer. Controller that get the returned value pass it directly to view, without reprocessing it.
3. In view, it will process the variable in order to displaying it. There will be loop to display list of data, get the column field from array then display it as a form default value, etc. View and model often developed in pair, because all needed field in view must be provided by the query in the Model.

The only ‘fat’ processing in Controller is the form_validation. I have answer it in your other question, how I wrote my form_validation rules and how to use it.

Below is my answers for your question above:

Q. When creating a new form and your
using CI’s form_helper I’m creating
arrays in the controller and passing
it to the view/form_input() method.
Should I be doing this in the
controller, the view, or a separate
file?

I rarely using form_helper. This is because most of my view is came from fellow designer or provided by client as the HTML file. I only use form_dropdown because it’s allow me to pass options as an array, instead of do foreach. For the other form element, I just use the one presented in the template file.

Q. In my controller, I create a method
for my form i.e., new_user() and in
my view/form_open() I specify a
different method in my controller to
handle the action (i.e., add(),
edit(), delete() ..etc) & that method
handles the validation. This is the
way that I perfer; however, I’ve had a
lot of difficulty passing the data
around if the validation fails. Any
suggestions?

When I create my application, I often only have 2 main methods in controller. admin is for displaying list and handle delete, and form to display and handle add and edit. Let me give example with a product module.

I will have product controller with these methods:

class Product extends MY_Controller {

  function index()
  {
    //for front page, display list of product
  }

  function detail()
  {
    //for front page, display single product detail
    //product id is passed as 3rd URI segment
    $id = intval($this->uri->rsegment(3));
  }

  function admin()
  {
    //for admin, display product list
    //receive id in _POST then do delete
    //after delete, do redirect to self, best practise
  }

  function form()
  {
    //for admin, handle add and edit
    $id = intval($this->uri->rsegment(3));
    //if id given and product detail data can be loaded, then it in 'edit' mode
    //else it in 'add' mode
    //after validation success, and insert/update success, redirect to product/admin
  }

}

Using this approach, I can avoid duplicate code and can maintain all code to always up to date. Almost all add & edit have same view and form field. In case add & edit form differ (such as edit user, do not allow changing username), by have $mode variable set to either add or edit, I can put simple if and display correct form, validation rules, and call appropriate model metods.

Q. I have an instance or two that when
I perform form validation I need to
validate against two $_POST variables.
An example would be, on validation I
need to query the database to
determine if the entered business
already exists (based off business
name and zip code) then redirect back
to the view and persist the post
variables. So far I haven’t been able
to find a way to create a custom
callback function to do this because
you can only pass in one parameter.
The only way that I’ve been able to
get this to work is if validation
passes, I then perform the database
check and if the business exists I put
the $_post in session/flashdata and
use redirect to load the view again.
The array that defines the form_input
attributes calls set_value for that is
where it pulls the flashdata for each
record in the array.

You can create your own validation rules. To pass more than one parameter, you can open the file system/libraries/Form_validation.php then see the function matches($str, $field) code. Your callback can have more than 1 parameter, and function matches($str, $field) code will show you how to read and use the second parameter.

I hope this will help you in learning and using CI. Waiting great web application from you 😉