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Produce HTML form elements for database columns

Maypole::Model:CDBI::AsForm - Produce HTML form elements for database columns


Maypole::Model:CDBI::AsForm - Produce HTML form elements for database columns


    package Music::CD;

    use Maypole::Model::CDBI::AsForm;

    use base 'Class::DBI';

    use CGI;


    sub create_or_edit {

        my $self = shift;

        my %cgi_field = $self->to_cgi;

        return start_form,

               (map { "<b>$_</b>: ". $cgi_field{$_}->as_HTML." <br>" } 




   . . .

    # Somewhere else in a Maypole application about beer...

   $beer->to_field('brewery', 'textfield', { 

                name => 'brewery_id', value => $beer->brewery,

                # however, no need to set value since $beer is object


   # Rate a beer

   $beer->to_field(rating =>  select => {

                items => [1 , 2, 3, 4, 5],


   # Select a Brewery to visit in the UK

   Brewery->to_field(brewery_id => {

                items => [ Brewery->search_like(location => 'UK') ],


  # Make a select for a boolean field

  $Pub->to_field('open' , { items => [ {'Open' => 1, 'Closed' => 0 } ] });

   $beer->to_field('brewery', {

                selected => $beer->brewery, # again not necessary since caller is obj.


    $beer->to_field('brewery', 'link_hidden', {r => $r, uri => ''.$beer->brewery});

    # an html link that is also a hidden input to the object. R is required to

    # make the uri  unless you  pass a  uri


    # Templates Usage

    <form ..>



     <span class="field"> [% classmetadata.colnames.$col %] : </span>

     [% object.to_field(col).as_XML %]


    . . .


     <span class="field"> Brewery : </span>

     [% object.to_field('brewery', { selected => 23} ).as_XML %]


    . . .



    # Advanced Usage

    # has_many select

    package Job;

    __PACKAGE__->has_a('job_employer' => 'Employer');

    __PACKAGE__->has_a('contact'  => 'Contact')

    package Contact;

    __PACKAGE__->has_a('cont_employer' => 'Employer');

    __PACKAGE__->has_many('jobs'  => 'Job',

                          { join => { job_employer => 'cont_employer' },

                            constraint => { 'finshed' => 0  },

                            order_by   => "created ASC",



    package Employer;

    __PACKAGE__->has_many('jobs'  => 'Job',);

    __PACKAGE__->has_many('contacts'  => 'Contact',

                          order_by => 'name DESC',


  # Choose some jobs to add to a contact (has multiple attribute).

  my $job_sel = Contact->to_field('jobs'); # Uses constraint and order by

  # Choose a job from $contact->jobs 

  my $job_sel = $contact->to_field('jobs');



This module helps to generate HTML forms for creating new database rows or editing existing rows. It maps column names in a database table to HTML form elements which fit the schema. Large text fields are turned into textareas, and fields with a has-a relationship to other Class::DBI tables are turned into select drop-downs populated with objects from the joined class.


This provides a convenient way to tweak AsForm's behavior in exceptional or not so exceptional instances. Below describes the arguments hash and example usages.

  $beer->to_field($col, $how, $args); 

  $beer->to_field($col, $args);

Not all _to_* methods pay attention to all arguments. For example, '_to_textfield' does not look in $args->{'items'} at all.

name -- the name the element will have , this trumps the derived name.

  $beer->to_field('brewery', 'readonly', {

                name => 'brewery_id'

value -- the initial value the element will have, trumps derived value

  $beer->to_field('brewery', 'textfield', { 

                name => 'brewery_id', value => $beer->brewery,

                # however, no need to set value since $beer is object

items -- array of items generally used to make select box options
Can be array of objects, hashes, arrays, or strings, or just a hash.

   # Rate a beer

   $beer->to_field(rating =>  select => {

                items => [1 , 2, 3, 4, 5],


   # Select a Brewery to visit in the UK

   Brewery->to_field(brewery_id => {

                items => [ Brewery->search_like(location => 'UK') ],


  # Make a select for a boolean field

  $Pub->to_field('open' , { items => [ {'Open' => 1, 'Closed' => 0 } ] });

selected -- something representing which item is selected in a select box

   $beer->to_field('brewery', {

                selected => $beer->brewery, # again not necessary since caller is obj.


Can be an simple scalar id, an object, or an array of either

class -- the class for which the input being made for field pertains to.
This in almost always derived in cases where it may be difficult to derive, -- # Select beers to serve on handpump Pub->to_field(handpumps => select => { class => 'Beer', order_by => 'name ASC', multiple => 1, });

column_type -- a string representing column type

  $pub->to_field('open', 'bool_select', {

                column_type => "bool('Closed', 'Open'),

column_nullable -- flag saying if column is nullable or not
Generally this can be set to get or not get a null/empty option added to a select box. AsForm attempts to call ``$class->column_nullable'' to set this and it defaults to true if there is no shuch method.

  $beer->to_field('brewery', { column_nullable => 1 });

r or request -- the Mapyole request object
uri -- uri for a link , used in methods such as _to_link_hidden

 $beer->to_field('brewery', 'link_hidden', 

          {r => $r, uri => ''.$beer->brewery}); 

 # an html link that is also a hidden input to the object. R is required to

 # make the uri  unless you  pass a  uri
order_by, constraint, join
These are used in making select boxes. order_by is a simple order by clause and constraint and join are hashes used to limit the rows selected. The difference is that join uses methods of the object and constraint uses static values. You can also specify these in the relationship definitions. See the relationships documentation of how to set arbitrayr meta info.

  BeerDB::LondonBeer->has_a('brewery', 'BeerDB::Brewery', 

                   order_by     => 'brewery_name ASC',

           constraint   => {location  => 'London'},

           'join'       => {'brewery_tablecolumn  => 'beer_obj_column'}, 


no_hidden_constraints --
Tell AsForm not to make hidden inputs for relationship constraints. It does this sometimes when making foreign inputs. However, i think it should not do this and that the FromCGI 's _create_related method should do it.


  $self->to_cgi([@columns, $args]);

This returns a hash mapping all the column names to HTML::Element objects representing form widgets. It takes two opitonal arguments -- a list of columns and a hashref of hashes of arguments for each column. If called with an object like for editing, the inputs will have the object's values.

  $self->to_cgi(); # uses $self->columns;  # most used

  $self->to_cgi(qw/brewery style rating/); # sometimes

  # and on rare occassions this is desireable if you have a lot of fields

  # and dont want to call to_field a bunch of times just to tweak one or 

  # two of them.

  $self->to_cgi(@cols, {brewery => {  

                                                                         how => 'textfield' # too big for select 


                                                style   => { 

                                                                         column_nullable => 0, 

                                                                         how => 'select', 

                                                                         items => ['Ale', 'Lager']



to_field($field [, $how][, $args])

This maps an individual column to a form element. The how argument can be used to force the field type into any you want. All that you need is a method named ``_to_$how'' in your class. Your class inherits many from AsForm already.

If how is specified but the class cannot call the method it maps to, then AsForm will issue a warning and the default input will be made. You can write your own ``_to_$how'' methods and AsForm comes with many. See HOW Methods. You can also pass this argument in $args->{how}.


  my $cgi = $class->search_inputs ([$args]); # optional $args

Returns hash or hashref of search inputs elements for a class making sure the inputs are empty of any initial values. You can specify what columns you want inputs for in $args->{columns} or by the method ``search_columns''. The default is ``display_columns''. If you want to te search on columns in related classes you can do that by specifying a one element hashref in place of the column name where the key is the related ``column'' (has_a or has_many method for example) and the value is a list ref of columns to search on in the related class.

Example: sub BeerDB::Beer::search_columns { return ( 'name' , 'rating', { brewery => [ 'name', 'location'] } ); }

  # Now foreign inputs are made for Brewery name and location and the

  # there will be no name clashing and processing can be automated.


  unselect any selected elements in a HTML::Element select list widget

_field_from_how($field, $how,$args)

Returns an input element based the ``how'' parameter or nothing at all. Override at will.

_field_from_relationship($field, $args)

Returns an input based on the relationship associated with the field or nothing. Override at will.

For has_a it will give select box

_field_from_column($field, $args)

Returns an input based on the column's characteristics, namely type, or nothing. Override at will.

recognized arguments

  selected => $object|$id,

  name     => $name,

  value    => $value,

  where    => SQL 'WHERE' clause,

  order_by => SQL 'ORDER BY' clause,

  constraint => hash of constraints to search

  limit    => SQL 'LIMIT' clause,

  items    => [ @items_of_same_type_to_select_from ],

  class => $class_we_are_selecting_from

  stringify => $stringify_coderef|$method_name

1. a select box out of a has_a or has_many related class. # For has_a the default behavior is to make a select box of every element in # related class and you choose one. #Or explicitly you can create one and pass options like where and order BeerDB::Beer->to_field('brewery','select', {where => ``location = 'Germany''');

  # For has_many the default is to get a multiple select box with all objects.

  # If called as an object method, the objects existing ones will be selected. 

  Brewery::BeerDB->to_field('beers','select', {where => "rating > 5"});

2. a select box for objects of arbitrary class -- say BeerDB::Beer for fun. # general BeerDB::Beer->to_field('', 'select', $options)

  BeerDB::Beer->to_field('', 'select'); # Select box of all the rows in class

                                                                  # with PK as ID, $Class->to_field() same.

  BeerDB::Beer->to_field('','select',{ where => "rating > 3 AND class like 'Ale'", order_by => 'rating DESC, beer_id ASC' , limit => 10});

  # specify exact where clause

3. If you already have a list of objects to select from --

  BeerDB:;Beer->to_field($col, 'select' , {items => $objects});

# 3. a select box for arbitrary set of objects # Pass array ref of objects as first arg rather than field $any_class_or_obj->to_field([BeerDB::Beer->search(favorite => 1)], 'select',);


Returns a select box for the an enum column type.


Returns a ``No/Yes'' select box for a boolean column type.

_to_hidden($field, $args)

This makes a hidden html element input. It uses the ``name'' and ``value'' arguments. If one or both are not there, it will look for an object in ``items->[0]'' or the caller. Then it will use $field or the primary key for name and the value of the column by the derived name.

_to_link_hidden($col, $args)

Makes a link with a hidden input with the id of $obj as the value and name. Name defaults to the objects primary key. The object defaults to self.


Creates inputs for a foreign class, usually related to the calling class or object. In names them so they do not clash with other names and so they can be processed generically. See _rename_foreign_inputs below and Maypole::Model::CDBI::FromCGI::classify_foreign_inputs.

Arguments this recognizes are :

        related_meta -- if you have this, great, othervise it will determine or die

        columns  -- list of columns to make inputs for 

        request (r) -- TODO the Maypole request so we can see what action


*Function* to make sense out of the ``selected'' argument which has values of the options that should be selected by default when making a select box. It can be in a number formats. This method returns a map of which options to select with the values being the keys in the map ( {val1 => 1, val2 = 1} ).

Currently this method handles the following formats for the ``selected'' argument and in the following ways

  Object                                -- uses the id method  to get the value

  Scalar                                -- assumes it *is* the value

  Array ref of objects  -- same as Object

  Arrays of data                -- uses the 0th element in each

  Hashes of data                -- uses key named 'id'


Internal api method to make the actual select box form elements. the data.

Items to make options out of can be Hash, Array, Array of CDBI objects. Array of scalars , Array or Array refs with cols from class, Array of hashes

_options_from_objects ( $objects, $args);

Private method to makes a options out of objects. It attempts to call each objects stringify method specified in $args->{stringify} as the content. Otherwise the default stringification prevails.

*Note only single primary keys supported


Makes a checkbox element -- TODO


Makes a radio button element -- TODO


_rename_foreign_input($html_el_or_hash_of_them); # changes made by reference

Recursively renames the foreign inputs made by _to_foreign_inputs so they can be processed generically. It uses foreign_input_delimiter.

So if an Employee is a Person who has_many Addresses and you call and the method 'foreign_input_delimiter' returns '__AF__' then



will get inputs for the Person as well as their Address (by default,

override _field_from_relationship to change logic) named like this:





And the processor would know to create this address, put the address id in person->{address} data slot, insert the person and put the person id in the employee->{person} data slot and then insert the employee with that data.


This tells AsForm what to use to delmit forieign input names. This is important to avoid name clashes as well as automating processing of forms.


This functions computes the dimensions of a textarea based on the value or the defaults.


1.0 15-07-2004 -- Initial version =head1 MAINTAINER

Maypole Developers


Peter Speltz, Aaron Trevena


Simon Cozens, Tony Bowden


  Testing - lots

  checkbox generalization

  radio generalization

  Make link_hidden use standard make_url stuff when it gets in Maypole

  How do you tell AF --" I want a has_many select box for this every time so,

     when you call "to_field($this_hasmany)" you get a select box


Please direct all correspondence regarding this module to: Maypole list.


Copyright 2003-2004 by Simon Cozens / Tony Bowden

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


the Class::DBI manpage, the Class::DBI::FromCGI manpage, the HTML::Element manpage.