Dave Rolsky > Chloro-0.06 > Chloro::Manual::Groups

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NAME ^

Chloro::Manual::Groups - Repeatable groups in forms

VERSION ^

version 0.06

WHAT'S A REPEATABLE GROUP? ^

Chloro provide a feature called "repeatable groups", or just "groups", in forms.

The idea is simple. It's quite common to have a group of fields in your form that you want to repeat. Maybe you want to offer a fixed number of repetitions, or you might let the user add additional groups through Javascript.

A good example would be phone numbers. The group might consist of a select field for phone numbers types (Home, Mobile, Work) and a text input for the phone number itself.

Processing this sort of data can be tricky. You need to associate each group with a specific phone number, and you need to distinguish new phone numbers from updates to existing numbers.

Chloro supports all of this through the use of groups.

GROUP DEFINITION ^

A group consists of a "repetition field" and a set of repeatable fields. The repetition field is a field that contains the keys that define each group. Typically, this will be some combination of database ids and identifiers for new fields.

Here's a group definition for our phone number group:

    group phone_number => (
        repetition_key => 'phone_number_id',
        (
            field phone_number_type => (
                isa      => 'Int',
                required => 1,
            ),
        ),
        (
            field phone_number => (
                isa      => 'NonEmptyStr',
                required => 1,
            ),
        ),
    );

The extra parentheses around the field definition are simply there so that the first field() subroutine call doesn't consume everything that comes after it.

The corresponding HTML for phone number group might look something like this:

    <div class="phone-number">
      <input name="phone_number_id" type="hidden" value="42" />

      <select name="phone_number.42.phone_number_type">
        <option value="1">Home</option>
        <option value="2">Mobile</option>
      </select>

      <input name="phone_number.42.phone_number" type="text" />
    </div>

    <div class="phone-number">
      <input name="phone_number_id" type="hidden" value="59" />

      <select name="phone_number.59.phone_number_type">
        <option value="1">Home</option>
        <option value="2">Mobile</option>
      </select>

      <input name="phone_number.59.phone_number" type="text" />
    </div>

If we provided Javascript to add new phone numbers, it could repeat all of these fields, replacing the phone_number_id with something like "new1", "new2", etc.

EMPTY GROUPS ^

If you provide a Javascript mechanism to add or delete groups, it's possible that you'll end up with groups that don't actually have any useful data.

By default, a group is empty if all of its fields are empty. However, you can define a custom is_empty_checker to decide if a group has data or not.

In our example above, it would be possible to have a group that just contains a type, but no phone number. In that case, we want to check for a phone number to determine whether a group is empty:

    package MyApp::Form::Contact;

    group phone_number => (
        ...,
        is_empty_checker => '_phone_number_is_empty',
    );

    sub _phone_number_is_empty {
        my $self   = shift;
        my $params = shift;
        my $prefix = shift;
        my $group  = shift;

        my $key = "$prefix.phone_number";

        return defined $params->{$key} && length $params->{$key};
    }

The is_empty_checker is called as a method on the form object. It receives three arguments.

The first argument are the parameters passed to the $form->process() method.

The second is the group's prefix, which is a combination of the group name and one of the values in the repetition_key, something like "phone_number.42".

The third argument is the Chloro::Group object for this group.

GROUP RESULTS ^

Grouped field data is handled differently from regular fields when generating results. When you call $resultset->results_as_hash(), you'll get a data structure back like this:

    {
        phone_number_id => [ 42, 59 ],
        phone_number => {
            42 => {
                phone_number_type => 1,
                phone_number      => '783-555-1236',
            },
            59 => {
                phone_number_type => 2,
                phone_number      => '524-555-5619',
            },
    }

No matter how many phone numbers are present, the phone_number_id field (our repetition_key) will always contain an array reference. The values for the repetition_key field will not include keys for empty groups.

AUTHOR ^

Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE ^

This software is Copyright (c) 2011 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)
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