HTML::Field - Generation of HTML form elements
use HTML::Field;
########## Creation of Field objects ##############
# A text field:
my $field1 = HTML::Field->new('Textfield',
name => 'fieldname',
value => 'current value',
default => 'default value',
size => 15,
maxlength => 15 );
# A Pasword field (has the same attributes as 'Textfield'):
my $field2 = HTML::Field->new('Passwd',
name => 'fieldname',
value => 'current value',
default => 'default value',
size => 15,
maxlength => 15 );
# A hidden field:
my $hidden = HTML::Field->new('Hidden',
name => 'sid',
value => 'cgiasf25k',
default => undef );
# A text area:
my $area = HTML::Field->new('Textarea',
name => 'address',
cols => 40,
rows => 4 );
# A 'select' tag. Options are given in an array reference; labels are
# given in a hash keyed by the options:
my $select = HTML::Field->new('Select',
name => 'select_color',
options => [qw(red yellow brown)],
default => 'red',
labels => {red => 'Color of apples',
yellow => 'Color of mangos!',
brown => 'Color of chocolate'},
multiple => undef, # Multiple is either true or false
size => 1 ); # Size of select box
# A radio button. Note that it will generate the HTML for all of its
# options, and those will be named as 'name_option'
my $radio_buttons = HTML::Field->new('Radio',
name => 'Flavors',
options => [qw(Lemon Strawberry Grapefruit)],
default => 'Grapefruit' );
# A single checkbox:
my $checkbox = HTML::Field->new('Checkbox',
name => 'Additional',
option => 'Strawberry',
default => 1,
read_only_tags => { true => 'X', false => 'o'});
# Render editable HTML
my ($key, $value) = $field->editable_html;
# Render read-only value
($key, $value) = $field->readonly_html;
# Render editable HTML for a new element
($key, $value) = $field->creation_html;
# Set a field's value from a CGI object, hash reference or scalar:
my $value = $field->value($cgi);
# or, get the filed's value:
$value = $field->value;
# The 'read_only_tags' attribute sets the representation of a
# check box or of radio buttons for a 'read only' rendering.
# This feature can be used to load different images to represent
# 'checked' radio buttons or check boxes.
# Primary Key text field:
my $field1 = HTML::Field->new('Textfield',
name => 'login',
size => 15,
maxlength => 15,
primary_key => 1 );
# When a text field is marked as 'primary' key, then
# it will not be editable once it has a value. This means that if you
# are displaying an empty form this will be an editable text field,
# but if you are displaying a database record for edition, then this
# field will not be editable and it will also be present as a hidden
# field in order to get sent back to the script.
# Primary key autogenerated by the database:
my $serial = HTML::Field->new('Textfield',
name => 'company_id',
size => 4,
maxlength => 4,
auto => 1 );
# The same as above applies if the field value is generated by the
# database. In that case, the value will never be editable; if the
# field has no value then a place holder will be returned instead.
HTML::Field objects are able to read their values from CGI objects, hash
references or plain scalars and then render those values as HTML fields or
simple read-only HTML. They are meant to ease the interface between CGI,
databases and templates.
IMPORTANT NOTE: This module does not validate the values of any HTML attributes
that you supply.
See HTML::FieldForm for a class that works on sets of HTML::Fields.
There are three
functional attributes for all Field objects:
"name", "value" and "default". By functional, I
mean that these attributes have other uses than solely appearing in HTML.
"value" and "default" have accessor/mutators named after
them; "name" is read-only and must be set during creation.
"name"
Of the three common, functional attributes only "name" is required.
"name" will be used for the following important things:
- 1. To look for the field value in a hash or a CGI object
- 2. As the key in the hashes returned by the html methods
- 3. As the name of the html tags produced
So, if you are using HTML::Template, it is adviceable to name the parameters of
your template the same as the fields you will use to populate it.
"value" and "default"
These two attributes define the value of the Field objects in different stages
of their existance. If you include a "default" for an object, it
will be the value that will be used since object creation until it is
explicitly changed by "value". The "reset_value" method
will set "value" equal to "default".
You can feed "value" with a hash reference, a CGI object or a scalar
value to set the value of a given field:
$field->value($cgi);
$field->value($hash_ref);
$field->value(4);
Several HTML attributes can be used within all field tags. There are two kinds
of HTML attributes: Those which can take a value and those which are just true
or false. For those which can have a value, their value can be any scalar and
it will simply be inculded in the field tag.
All of these attributes may be set during object creation and also using their
accessor/mutator (implemented via AUTOLOAD).
The following HTML attributes may be used with all of the HTML::Field classes:
- accesskey
- id
- title
- class
- style
- lang
- dir
- tabindex
- disabled (Boolean)
- readonly (Boolean)
Each HTML::Field class may have its own, particular attributes. See below.
Besides the accessor/mutator methods explained above, there are three methods
common to every Field object:
- $field->reset_values
- Makes "value" equal to "default".
- %hash = $field->editable_html
- The returned hash will have the field's name as key and its HTML field tag
as value. It returns a hash because this way it is simpler to include it
in a template (think HTML::Template). In this case, you can use it like
this:
$template->param($field->editable_html);
- %hash = $field->readonly_html
- Same as above, except that the HTML will not be a form tag but only a
read-only HTML representation of the field's value. Usually this read-only
HTML is simply the value of the field.
For the checkboxes and radio buttons, it is possible to have images or any
other mark up to display 'true' and 'false' states for reading via the
"readonly_tags" attribute; you can see it in the SYNOPSIS. This
attribute has its accessor/mutator of the same name.
- %hash = $field->creation_html
- This method will return an empty HTML field for edition. Normally this
method should be used when creating a new record in a database, as it will
allow for the edition of fields marked as 'primary_key' (not for 'auto').
See the next section for an extended explanation.
If a form is displayed for the entry of a new record, then there are two
scenarios regarding primary keys:
- "auto" -- Primary key is generated by the database or
application
- In this case the system generates a value for the primary key prior to its
insertion in the database. This value will not exist when the empty form
is served to the client for the first time, so it should not be included.
However, it will exist and is needed if the record is requested for
updating. In this case it will be sent in a non-editable form, followed by
a hidden field (in the case of text fields). Think of using a hidden field
for this case.
- "primary_key" -- Primary key is entered by the user
- If the primary key of a record will be supplied by the user, then the
field must be empty and editable when the form is first displayed. Once
the record exists the primary key will be sent in a read-only form
followed by a hidden field. This way the primary key will be present in
the data sent back to the server for updating the database.
Note that because the field needs to be editable for record creation, a
hidden field cannot be marked as primary key.
In summary, calling "creation_html" on a field marked as
"primary_key" will display an editable field. Calling
"editable_html" will return a read-only value followed with a hidden
field.
Calling "creation_html" on a field marked as "auto" will
only display an HTML comment as a marker. Calling "editable_html"
will display a hidden field instead, and in the case of a text field, it will
also display its value.
You can only mark text fields as 'primary_key'; text and hidden fields support
'auto'.
ATTRIBUTES
These attributes are optional. They have accessor/mutator methods (via
AUTOLOAD).
- size
- maxlength
- primary_key (Not an HTML attribute; see explanation above)
- auto (Not an HTML attribute; see explanation above)
Fields of this class must have a value when issueing editable HTML or they will
raise an exception.
These fields may be marked as "auto", but not as
"primary_key".
- auto (Not an HTML attribute; see explanation above)
ATTRIBUTES
These attributes are optional. They have accessor/mutator methods (via
AUTOLOAD).
- size
- maxlength
ATTRIBUTES
These attributes are optional. They have accessor/mutator methods (via
AUTOLOAD).
- cols
- rows
- wrap
This class is useful to implement single checkboxes; in other words, checkboxes
that have their own name.
ATTRIBUTES
These attributes are optional. They have accessor/mutator methods (via
AUTOLOAD).
- readonly_tags
- This attribute can take a hash with the keys 'true' and 'false', which
should point to read-only representations of checked (true) or not checked
(false) fields. For example:
$field->readonly_tags(
true => '<img src="checked.png" alt="Checked"/>',
false => '<img src="not_checked.png" alt="Not checked"/>',
);
Default is '+' for true and '-' for false.
ATTRIBUTES
These attributes have accessor/mutator methods (via AUTOLOAD).
- size -- Optional
- multiple -- Optional (true or false only)
- options -- Required
- Array reference of options.
- labels -- Required
- "labels" will accept a hash of labels keyed by option.
Class to create radio button fields. A single object will generate as many radio
buttons as options it has. These buttons will be named like this:
field_option
So, following the example in the synopsis, we would have:
Flavors_Lemon,
Flavors_Strawberry, and
Flavors_Grapefruit.
ATTRIBUTES
These attributes have accessor/mutator methods (via AUTOLOAD).
- options -- Required
- Array reference of options.
- readonly_tags
- See HTML::Field::Checkbox for an explanation.
HTML::FieldForm is a module that manages sets of HTML::Field objects.
Julio Fraire, <julio.fraire@gmail.com<gt>
Copyright (C) 2009 by Julio Fraire
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself, either Perl version 5.8.8 or, at your option,
any later version of Perl 5 you may have available.