HTML::FormHandler::Manual::Database(3p)

NAME
HTML::FormHandler::Manual::Database - FormHandler use recipes

VERSION
version 0.40068

SYNOPSIS
Manual Index

Information on interfacing FormHandler forms and fields with a database. Also see HTML::FormHandler::TraitFor::Model::DBIC.

Form Models
For a database form, use a model base class that interfaces with the database, such as HTML::FormHandler::Model::DBIC, which needs to be installed as a separate package. There's also a sample 'object' model in HTML::FormHandler::Model::Object, which will update a simple object.

When using a database model, form field values for the row are retrieved from the database using the field 'accessor' attributes (defaults to field name) as database class accessors.

FormHandler will use relationships to populate single and multiple selection lists, and validate input. A 'single' relationship is processed by HTML::FormHandler::Field::Compound. A 'has_many' relationship is processed by HTML::FormHandler::Field::Repeatable.

Do not use database row method names, such as 'delete', as field names in a database form.

You can pass in either the primary key or a row object to the form. If a primary key (item_id) is passed in, you must also provide the schema. The model will use the item_class (DBIC source name) to fetch the row from the database. If you pass in a row object (item), the schema, item_class, and item_id will be set from the row.

Executing "$form->process( item => $row, params => $params );" will validate the parameters and then update or create the database row object.

Fields that map to database relationships

  Select
A select field will automatically retrieve a select list from the database, if the proper column names are provided. Single selects handle 'belongs_to' relationships, where the related table is used to construct a selection list from the database.

See also HTML::FormHandler::Field::Select and 'lookup_options' in HTML::FormHandler::TraitFor::Model::DBIC.

  Multiple Select
A multiple select is either a 'Select' with multiple => 1 set, or a field of the 'Multiple' type. The name of a Multiple select which pulls options from the database automatically should be the name of the 'many_to_many' relationship. The 'value' of the field is derived from the 'has_many' part of the relationship.

The primary key is used for the 'id' of the select. The 'label' column of the select is assumed to be 'name'. If the label column has a different name, it must be specified with 'label_column'.

Pertinent attributes:

   label_column
   active_column
   sort_column

See also HTML::FormHandler::Field::Select and HTML::FormHandler::Model::DBIC.

  Compound fields
A compound field represents a single relationship to another table. Although most compound relations can be handled without providing a primary key, in some circumstances you may need to provide a PrimaryKey field, or add extra values in update_model.

See also HTML::FormHandler::Field::Compound.

The default for compound fields is that if all subfields are empty, the value of the compound field is set to undef (null). For some types of relations, you may want to set the 'not_nullable' flag to force the field to contain all subfields anyway, such as when the related rows are not deleted when empty. See test t/compound/empty.t for a demonstration of the difference in output.

  Repeatable fields
The 'Repeatable' field type allows you to update arrays of columns from related tables easily. You will need to provide a 'PrimaryKey' hidden field in the compound field contained in the Repeatable.

  has_field 'addresses' => ( type => 'Repeatable' );
  has_field 'addresses.address_id' => ( type => 'PrimaryKey' );
  has_field 'addresses.street';
  has_field 'addresses.city';
  has_field 'addresses.state';

There are some complications with creating Repeatable elements (with the PrimaryKey field set to undef) in a database and re-presenting the form. See HTML::FormHandler::Field::Repeatable for more info.

Flags

  writeonly
Do not read the value from the 'item' when populating the form.

  noupdate
Do not update the database with this field, i.e. do not include it in "$form->value".

Form generator
A DBIC form generator is installed with the HTML::FormHandler::Model::DBIC package. See HTML::FormHandler::Generator::DBIC.

There's also a role, HTML::FormHandler::TraitFor::DBICFields, that allows simple form fields to be auto-generated from a DBIC result class.

    my $form = HTML::FormHandler::Model::DBIC->new_with_traits(
        traits => ['HTML::FormHandler::TraitFor::DBICFields'],
        includes => ['title', 'author' ],
        field_list => [ 'submit' => { type => 'Submit', value => 'Save', order => 99 } ],
        item => $book );

AUTHOR
FormHandler Contributors - see HTML::FormHandler

COPYRIGHT AND LICENSE
This software is copyright (c) 2017 by Gerda Shank.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.