---
name: "Jifty::Param::Schema"
section: "3pm"
platform: "linux"
package: "libjifty-perl"
version: "1.10518+dfsg-2"
release: "Debian 7 (Wheezy)"
platforms: ["linux"]
url: "https://new.carta.tech/Jifty::Param::Schema"
---

# Jifty::Param::Schema(3pm)

Declare parameters of a Jifty action with ease.

## NAME

Jifty::Param::Schema - Declare parameters of a Jifty action with ease.

## SYNOPSIS

```
    package MyApp::Action::Login;
    use Jifty::Param::Schema;
    use Jifty::Action schema {
    param email =>
        label is 'Email address',
        is mandatory,
        ajax validates;
    param password =>
        type is 'password',
        label is 'Password',
        is mandatory;
    param remember =>
        type is 'checkbox',
        label is 'Remember me?',
        hints is 'If you want, your browser can remember your login for you',
        default is 0;
    };
```

## DESCRIPTION

This module provides a simple syntax to declare action parameters.

It re-exports `"defer"` and `"lazy"` from Scalar::Defer, for setting parameter fields that must be recomputed at request-time:

```
    param name =>
        default is defer { Jifty->web->current_user->name };
```

See Scalar::Defer for more information about `"defer"`.

### schema

The `"schema"` block from a Jifty::Action subclass describes an action for a Jifty application.

Within the `"schema"` block, the localization function `"_"` is redefined with `"defer"`, so that it resolves into a dynamic value that will be recalculated upon each request, according to the user's current language preference.

### param

Each `"param"` statement inside the `"schema"` block sets out the name and attributes used to describe one named parameter, which is then used to build a Jifty::Param object.  That class defines possible field names to use in the declarative syntax here.

The `"param"` function is not available outside the `"schema"` block.

## ALIASES

In addition to the labels provided by Jifty::Web::Form::Field and Jifty::Param, this module offers the following aliases:

```
    ajax validates,             # ajax_validates is 1
    ajax canonicalizes,         # ajax_canonicalizes is 1
    order is -1,                # sort_order is -1
    default is 0,               # default_value is 0
    valid are qw( 1 2 3 ),      # valid_values are qw( 1 2 3 )
    available are qw( 1 2 3 ),  # available_values are qw( 1 2 3 )
    render as 'select',         # render_as is 'select'
```

## SEE ALSO

Object::Declare, Scalar::Defer

### merge\_params HASHREF HASHREF

Takes two hashrefs. Merges them together and returns the merged hashref.

```
    - Empty fields in subclasses don't override nonempty fields in superclass anymore.
    - Arrays don't merge; e.g. if parent class's valid_values is [1,2,3,4], and
      subclass's valid_values() is [1,2], they don't somehow become [1,2,3,4,1,2].
```

BUG: This should either be a private routine or factored out into Jifty::Util