# Creating Forms Using Zend_Form

The Zend_Form class is used to aggregate form elements, display groups, and subforms. It can then perform the following actions on those items:

- Validation, including retrieving error codes and messages

- Value aggregation, including populating items and retrieving both filtered and unfiltered values from all items

- Iteration over all items, in the order in which they are entered or based on the order hints retrieved from each item

- Rendering of the entire form, either via a single decorator that performs custom rendering or by iterating over each item in the form

While forms created with Zend_Form may be complex, probably the best use case is for simple forms; its best use is for Rapid Application Development (RAD) and prototyping.

At its most basic, you simply instantiate a form object:

    // Generic form object:
    $form = new Zend_Form();

    // Custom form object:
    $form = new My_Form()

You can optionally pass in a instance of Zend_Config or an array, which will be used to set object state and potentially create new elements:

    // Passing in configuration options:
    $form = new Zend_Form($config);

Zend_Form is iterable, and will iterate over elements, display groups, and subforms, using the order they were registered and any order index each may have. This is useful in cases where you wish to render the elements manually in the appropriate order.

Zend_Form's magic lies in its ability to serve as a factory for elements and display groups, as well as the ability to render itself through decorators.

## Plugin Loaders

Zend_Form makes use of Zend_Loader_PluginLoader to allow developers to specify the locations of alternate elements and decorators. Each has its own plugin loader associated with it, and general accessors are used to retrieve and modify each.

The following loader types are used with the various plugin loader methods: 'element' and 'decorator'. The type names are case insensitive.

The methods used to interact with plugin loaders are as follows:

- setPluginLoader($loader, $type): $loader is the plugin loader object itself, while type is one of the types specified above. This sets the plugin loader for the given type to the newly specified loader object.

- getPluginLoader($type): retrieves the plugin loader associated with $type.

- addPrefixPath($prefix, $path, $type = null): adds a prefix/path association to the loader specified by $type. If $type is `NULL`, it will attempt to add the path to all loaders, by appending the prefix with each of "_Element" and "_Decorator"; and appending the path with "Element/" and "Decorator/". If you have all your extra form element classes under a common hierarchy, this is a convenience method for setting the base prefix for them.

- addPrefixPaths(array $spec): allows you to add many paths at once to one or more plugin loaders. It expects each array item to be an array with the keys 'path', 'prefix', and 'type'.

Additionally, you can specify prefix paths for all elements and display groups created through a Zend_Form instance using the following methods:

- addElementPrefixPath($prefix, $path, $type = null): Just like addPrefixPath(), you must specify a class prefix and a path. `$type`, when specified, must be one of the plugin loader types specified by Zend_Form_Element; see the element plugins section for more information on valid `$type` values. If no `$type` is specified, the method will assume it is a general prefix for all types.

- addDisplayGroupPrefixPath($prefix, $path): Just like addPrefixPath(), you must specify a class prefix and a path; however, since display groups only support decorators as plugins, no `$type` is necessary.

Custom elements and decorators are an easy way to share functionality between forms and encapsulate custom functionality. See the Custom Label example in the elements documentation for an example of how custom elements can be used as replacements for standard classes.

## Elements

Zend_Form provides several accessors for adding and removing form elements from a form. These can take element object instances or serve as factories for instantiating the element objects themselves.

The most basic method for adding an element is addElement(). This method can take either an object of type Zend_Form_Element (or of a class extending Zend_Form_Element), or arguments for building a new element -- including the element type, name, and any configuration options.

Some examples:

    // Using an element instance:
    $element = new Zend_Form_Element_Text('foo');
    $form->addElement($element);

    // Using a factory
    //
    // Creates an element of type Zend_Form_Element_Text with the
    // name of 'foo':
    $form->addElement('text', 'foo');

    // Pass label option to the element:
    $form->addElement('text', 'foo', array('label' => 'Foo:'));

addElement() Implements Fluent Interface

addElement() implements a fluent interface; that is to say, it returns the Zend_Form object, and not the element. This is done to allow you to chain together multiple addElement() methods or other form methods that implement the fluent interface (all setters in Zend_Form implement the pattern).

If you wish to return the element instead, use createElement(), which is outlined below. Be aware, however, that createElement() does not attach the element to the form.

Internally, addElement() actually uses createElement() to create the element before attaching it to the form.

Once an element has been added to the form, you can retrieve it by name. This can be done either by using the getElement() method or by using overloading to access the element as an object property:

    // getElement():
    $foo = $form->getElement('foo');

    // As object property:
    $foo = $form->foo;

Occasionally, you may want to create an element without attaching it to the form (for instance, if you wish to make use of the various plugin paths registered with the form, but wish to later attach the object to a sub form). The createElement() method allows you to do so:

    // $username becomes a Zend_Form_Element_Text object:
    $username = $form->createElement('text', 'username');

### Populating and Retrieving Values

After validating a form, you will typically need to retrieve the values so you can perform other operations, such as updating a database or notifying a web service. You can retrieve all values for all elements using getValues(); getValue($name) allows you to retrieve a single element's value by element name:

    // Get all values:
    $values = $form->getValues();

    // Get only 'foo' element's value:
    $value = $form->getValue('foo');

Sometimes you'll want to populate the form with specified values prior to rendering. This can be done with either the setDefaults() or populate() methods:

    $form->setDefaults($data);
    $form->populate($data);

On the flip side, you may want to clear a form after populating or validating it; this can be done using the reset() method:

    $form->reset();

### Global Operations

Occasionally you will want certain operations to affect all elements. Common scenarios include needing to set plugin prefix paths for all elements, setting decorators for all elements, and setting filters for all elements. As examples:

Setting Prefix Paths for All Elements

You can set prefix paths for all elements by type, or using a global prefix. Some examples:

    // Set global prefix path:
    // Creates paths for prefixes My_Foo_Filter, My_Foo_Validate,
    // and My_Foo_Decorator
    $form->addElementPrefixPath('My_Foo', 'My/Foo/');

    // Just filter paths:
    $form->addElementPrefixPath('My_Foo_Filter',
                                'My/Foo/Filter',
                                'filter');

    // Just validator paths:
    $form->addElementPrefixPath('My_Foo_Validate',
                                'My/Foo/Validate',
                                'validate');

    // Just decorator paths:
    $form->addElementPrefixPath('My_Foo_Decorator',
                                'My/Foo/Decorator',
                                'decorator');

Setting Decorators for All Elements

You can set decorators for all elements. setElementDecorators() accepts an array of decorators, just like setDecorators(), and will overwrite any previously set decorators in each element. In this example, we set the decorators to simply a ViewHelper and a Label:

    $form->setElementDecorators(array(
        'ViewHelper',
        'Label'
    ));

Setting Decorators for Some Elements

You can also set decorators for a subset of elements, either by inclusion or exclusion. The second argument to setElementDecorators() may be an array of element names; by default, specifying such an array will set the specified decorators on those elements only. You may also pass a third argument, a flag indicating whether this list of elements is for inclusion or exclusion purposes. If the flag is `FALSE`, it will decorate all elements except those in the passed list. As with standard usage of the method, any decorators passed will overwrite any previously set decorators in each element.

In the following snippet, we indicate that we want only the ViewHelper and Label decorators for the 'foo' and 'bar' elements:

    $form->setElementDecorators(
        array(
            'ViewHelper',
            'Label'
        ),
        array(
            'foo',
            'bar'
        )
    );

On the flip side, with this snippet, we'll now indicate that we want to use only the ViewHelper and Label decorators for every element except the 'foo' and 'bar' elements:

    $form->setElementDecorators(
        array(
            'ViewHelper',
            'Label'
        ),
        array(
            'foo',
            'bar'
        ),
        false
    );

Some Decorators are Inappropriate for Some Elements

While setElementDecorators() may seem like a good solution, there are some cases where it may actually end up with unexpected results. For example, the various button elements (Submit, Button, Reset) currently use the label as the value of the button, and only use ViewHelper and DtDdWrapper decorators -- preventing an additional labels, errors, and hints from being rendered. The example above would duplicate some content (the label) for button elements.

You can use the inclusion/exclusion array to overcome this issue as noted in the previous example.

So, use this method wisely, and realize that you may need to exclude some elements or manually change some elements' decorators to prevent unwanted output.

Setting Filters for All Elements

In some cases, you may want to apply the same filter to all elements; a common case is to trim() all values:

    $form->setElementFilters(array('StringTrim'));

### Methods For Interacting With Elements

The following methods may be used to interact with elements:

- createElement($element, $name = null, $options = null)

- addElement($element, $name = null, $options = null)

- addElements(array $elements)

- setElements(array $elements)

- getElement($name)

- getElements()

- removeElement($name)

- clearElements()

- setDefaults(array $defaults)

- setDefault($name, $value)

- getValue($name)

- getValues()

- getUnfilteredValue($name)

- getUnfilteredValues()

- setElementFilters(array $filters)

- setElementDecorators(array $decorators)

- addElementPrefixPath($prefix, $path, $type = null)

- addElementPrefixPaths(array $spec)

## Display Groups

Display groups are a way to create virtual groupings of elements for display purposes. All elements remain accessible by name in the form, but when iterating over the form or rendering, any elements in a display group are rendered together. The most common use case for this is for grouping elements in fieldsets.

The base class for display groups is Zend_Form_DisplayGroup. While it can be instantiated directly, it is usually best to use Zend_Form's addDisplayGroup() method to do so. This method takes an array of element names as its first argument, and a name for the display group as its second argument. You may optionally pass in an array of options or a Zend_Config object as the third argument.

Assuming that the elements 'username' and 'password' are already set in the form, the following code would group these elements in a 'login' display group:

    $form->addDisplayGroup(array('username', 'password'), 'login');

You can access display groups using the getDisplayGroup() method, or via overloading using the display group's name:

    // Using getDisplayGroup():
    $login = $form->getDisplayGroup('login');

    // Using overloading:
    $login = $form->login;

Default Decorators Do Not Need to Be Loaded

By default, the default decorators are loaded during object initialization. You can disable this by passing the 'disableLoadDefaultDecorators' option when creating a display group:

    $form->addDisplayGroup(
        array('foo', 'bar'),
        'foobar',
        array('disableLoadDefaultDecorators' => true)
    );

This option may be mixed with any other options you pass, both as array options or in a Zend_Config object.

### Global Operations

Just as with elements, there are some operations which might affect all display groups; these include setting decorators and setting the plugin path in which to look for decorators.

Setting Decorator Prefix Path for All Display Groups

By default, display groups inherit whichever decorator paths the form uses; however, if they should look in alternate locations, you can use the addDisplayGroupPrefixPath() method.

    $form->addDisplayGroupPrefixPath('My_Foo_Decorator', 'My/Foo/Decorator');

Setting Decorators for All Display Groups

You can set decorators for all display groups. setDisplayGroupDecorators() accepts an array of decorators, just like setDecorators(), and will overwrite any previously set decorators in each display group. In this example, we set the decorators to simply a fieldset (the FormElements decorator is necessary to ensure that the elements are iterated):

    $form->setDisplayGroupDecorators(array(
        'FormElements',
        'Fieldset'
    ));

### Using Custom Display Group Classes

By default, Zend_Form uses the Zend_Form_DisplayGroup class for display groups. You may find you need to extend this class in order to provided custom functionality. addDisplayGroup() does not allow passing in a concrete instance, but does allow specifying the class to use as one of its options, using the 'displayGroupClass' key:

    // Use the 'My_DisplayGroup' class
    $form->addDisplayGroup(
        array('username', 'password'),
        'user',
        array('displayGroupClass' => 'My_DisplayGroup')
    );

If the class has not yet been loaded, Zend_Form will attempt to do so using Zend_Loader.

You can also specify a default display group class to use with the form such that all display groups created with the form object will use that class:

    // Use the 'My_DisplayGroup' class for all display groups:
    $form->setDefaultDisplayGroupClass('My_DisplayGroup');

This setting may be specified in configurations as 'defaultDisplayGroupClass', and will be loaded early to ensure all display groups use that class.

### Methods for Interacting With Display Groups

The following methods may be used to interact with display groups:

- addDisplayGroup(array $elements, $name, $options = null)

- addDisplayGroups(array $groups)

- setDisplayGroups(array $groups)

- getDisplayGroup($name)

- getDisplayGroups()

- removeDisplayGroup($name)

- clearDisplayGroups()

- setDisplayGroupDecorators(array $decorators)

- addDisplayGroupPrefixPath($prefix, $path)

- setDefaultDisplayGroupClass($class)

- getDefaultDisplayGroupClass($class)

### Zend_Form_DisplayGroup Methods

Zend_Form_DisplayGroup has the following methods, grouped by type:

- Configuration:

  - setOptions(array $options)

  - setConfig(Zend_Config $config)

- Metadata:

  - setAttrib($key, $value)

  - addAttribs(array $attribs)

  - setAttribs(array $attribs)

  - getAttrib($key)

  - getAttribs()

  - removeAttrib($key)

  - clearAttribs()

  - setName($name)

  - getName()

  - setDescription($value)

  - getDescription()

  - setLegend($legend)

  - getLegend()

  - setOrder($order)

  - getOrder()

- Elements:

  - createElement($type, $name, array $options = array())

  - addElement($typeOrElement, $name, array $options = array())

  - addElements(array $elements)

  - setElements(array $elements)

  - getElement($name)

  - getElements()

  - removeElement($name)

  - clearElements()

- Plugin loaders:

  - setPluginLoader(Zend_Loader_PluginLoader $loader)

  - getPluginLoader()

  - addPrefixPath($prefix, $path)

  - addPrefixPaths(array $spec)

- Decorators:

  - addDecorator($decorator, $options = null)

  - addDecorators(array $decorators)

  - setDecorators(array $decorators)

  - getDecorator($name)

  - getDecorators()

  - removeDecorator($name)

  - clearDecorators()

- Rendering:

  - setView(Zend_View_Interface $view = null)

  - getView()

  - render(Zend_View_Interface $view = null)

- I18n:

  - setTranslator(Zend_Translate_Adapter $translator = null)

  - getTranslator()

  - setDisableTranslator($flag)

  - translatorIsDisabled()

## Sub Forms

Sub forms serve several purposes:

- Creating logical element groups. Since sub forms are simply forms, you can validate subforms as individual entities.

- Creating multi-page forms. Since sub forms are simply forms, you can display a separate sub form per page, building up multi-page forms where each form has its own validation logic. Only once all sub forms validate would the form be considered complete.

- Display groupings. Like display groups, sub forms, when rendered as part of a larger form, can be used to group elements. Be aware, however, that the master form object will have no awareness of the elements in sub forms.

A sub form may be a Zend_Form object, or, more typically, a Zend_Form_SubForm object. The latter contains decorators suitable for inclusion in a larger form (i.e., it does not render additional HTML form tags, but does group elements). To attach a sub form, simply add it to the form and give it a name:

    $form->addSubForm($subForm, 'subform');

You can retrieve a sub form using either getSubForm($name) or overloading using the sub form name:

    // Using getSubForm():
    $subForm = $form->getSubForm('subform');

    // Using overloading:
    $subForm = $form->subform;

Sub forms are included in form iteration, although the elements they contain are not.

### Global Operations

Like elements and display groups, there are some operations that might need to affect all sub forms. Unlike display groups and elements, however, sub forms inherit most functionality from the master form object, and the only real operation that may need to be performed globally is setting decorators for sub forms. For this purpose, there is the setSubFormDecorators() method. In the next example, we'll set the decorator for all subforms to be simply a fieldset (the FormElements decorator is needed to ensure its elements are iterated):

    $form->setSubFormDecorators(array(
        'FormElements',
        'Fieldset'
    ));

### Methods for Interacting With Sub Forms

The following methods may be used to interact with sub forms:

- addSubForm(Zend_Form $form, $name, $order = null)

- addSubForms(array $subForms)

- setSubForms(array $subForms)

- getSubForm($name)

- getSubForms()

- removeSubForm($name)

- clearSubForms()

- setSubFormDecorators(array $decorators)

## Metadata and Attributes

While a form's usefulness primarily derives from the elements it contains, it can also contain other metadata, such as a name (often used as a unique ID in the HTML markup); the form action and method; the number of elements, groups, and sub forms it contains; and arbitrary metadata (usually used to set HTML attributes for the form tag itself).

You can set and retrieve a form's name using the name accessors:

    // Set the name:
    $form->setName('registration');

    // Retrieve the name:
    $name = $form->getName();

To set the action (url to which the form submits) and method (method by which it should submit, e.g., 'POST' or '`GET`'), use the action and method accessors:

    // Set the action and method:
    $form->setAction('/user/login')
         ->setMethod('post');

You may also specify the form encoding type specifically using the enctype accessors. Zend_Form defines two constants, `Zend_Form::ENCTYPE_URLENCODED` and `Zend_Form::ENCTYPE_MULTIPART`, corresponding to the values 'application/x-www-form-urlencoded' and 'multipart/form-data', respectively; however, you can set this to any arbitrary encoding type.

    // Set the action, method, and enctype:
    $form->setAction('/user/login')
         ->setMethod('post')
         ->setEnctype(Zend_Form::ENCTYPE_MULTIPART);

The method, action, and enctype are only used internally for rendering, and not for any sort of validation.

Zend_Form implements the Countable interface, allowing you to pass it as an argument to count:

    $numItems = count($form);

Setting arbitrary metadata is done through the attribs accessors. Since overloading in Zend_Form is used to access elements, display groups, and sub forms, this is the only method for accessing metadata.

    // Setting attributes:
    $form->setAttrib('class', 'zend-form')
         ->addAttribs(array(
             'id'       => 'registration',
             'onSubmit' => 'validate(this)',
         ));

    // Retrieving attributes:
    $class = $form->getAttrib('class');
    $attribs = $form->getAttribs();

    // Remove an attribute:
    $form->removeAttrib('onSubmit');

    // Clear all attributes:
    $form->clearAttribs();

## Decorators

Creating the markup for a form is often a time-consuming task, particularly if you plan on re-using the same markup to show things such as validation errors, submitted values, etc. Zend_Form's answer to this issue is decorators.

Decorators for Zend_Form objects can be used to render a form. The FormElements decorator will iterate through all items in a form -- elements, display groups, and sub forms -- and render them, returning the result. Additional decorators may then be used to wrap this content, or append or prepend it.

The default decorators for Zend_Form are FormElements, HtmlTag (wraps in a definition list), and Form; the equivalent code for creating them is as follows:

    $form->setDecorators(array(
        'FormElements',
        array('HtmlTag', array('tag' => 'dl')),
        'Form'
    ));

This creates output like the following:

    <form action="/form/action" method="post">
    <dl>
    ...
    </dl>
    </form>

Any attributes set on the form object will be used as HTML attributes of the <form> tag.

Default Decorators Do Not Need to Be Loaded

By default, the default decorators are loaded during object initialization. You can disable this by passing the 'disableLoadDefaultDecorators' option to the constructor:

    $form = new Zend_Form(array('disableLoadDefaultDecorators' => true));

This option may be mixed with any other options you pass, both as array options or in a Zend_Config object.

Using Multiple Decorators of the Same Type

Internally, Zend_Form uses a decorator's class as the lookup mechanism when retrieving decorators. As a result, you cannot register multiple decorators of the same type; subsequent decorators will simply overwrite those that existed before.

To get around this, you can use aliases. Instead of passing a decorator or decorator name as the first argument to addDecorator(), pass an array with a single element, with the alias pointing to the decorator object or name:

    // Alias to 'FooBar':
    $form->addDecorator(array('FooBar' => 'HtmlTag'), array('tag' => 'div'));

    // And retrieve later:
    $form = $element->getDecorator('FooBar');

In the addDecorators() and setDecorators() methods, you will need to pass the 'decorator' option in the array representing the decorator:

    // Add two 'HtmlTag' decorators, aliasing one to 'FooBar':
    $form->addDecorators(
        array('HtmlTag', array('tag' => 'div')),
        array(
            'decorator' => array('FooBar' => 'HtmlTag'),
            'options' => array('tag' => 'dd')
        ),
    );

    // And retrieve later:
    $htmlTag = $form->getDecorator('HtmlTag');
    $fooBar  = $form->getDecorator('FooBar');

You may create your own decorators for generating the form. One common use case is if you know the exact HTML you wish to use; your decorator could create the exact HTML and simply return it, potentially using the decorators from individual elements or display groups.

The following methods may be used to interact with decorators:

- addDecorator($decorator, $options = null)

- addDecorators(array $decorators)

- setDecorators(array $decorators)

- getDecorator($name)

- getDecorators()

- removeDecorator($name)

- clearDecorators()

Zend_Form also uses overloading to allow rendering specific decorators. __call() will intercept methods that lead with the text 'render' and use the remainder of the method name to lookup a decorator; if found, it will then render that single decorator. Any arguments passed to the method call will be used as content to pass to the decorator's render() method. As an example:

    // Render only the FormElements decorator:
    echo $form->renderFormElements();

    // Render only the fieldset decorator, passing in content:
    echo $form->renderFieldset("<p>This is fieldset content</p>");

If the decorator does not exist, an exception is raised.

## Validation

A primary use case for forms is validating submitted data. Zend_Form allows you to validate an entire form, a partial form, or responses for XmlHttpRequests (AJAX). If the submitted data is not valid, it has methods for retrieving the various error codes and messages for elements and sub forms.

To validate a full form, use the isValid() method:

    if (!$form->isValid($_POST)) {
        // failed validation
    }

isValid() will validate every required element, and any unrequired element contained in the submitted data.

Sometimes you may need to validate only a subset of the data; for this, use isValidPartial($data):

    if (!$form->isValidPartial($data)) {
        // failed validation
    }

isValidPartial() only attempts to validate those items in the data for which there are matching elements; if an element is not represented in the data, it is skipped.

When validating elements or groups of elements for an AJAX request, you will typically be validating a subset of the form, and want the response back in JSON. processAjax() does precisely that:

    $json = $form->processAjax($data);

You can then simply send the JSON response to the client. If the form is valid, this will be a boolean `TRUE` response. If not, it will be a javascript object containing key/message pairs, where each 'message' is an array of validation error messages.

For forms that fail validation, you can retrieve both error codes and error messages, using getErrors() and getMessages(), respectively:

    $codes = $form->getErrors();
    $messages = $form->getMessages();

Since the messages returned by getMessages() are an array of error code/message pairs, getErrors() is typically not needed.

You can retrieve codes and error messages for individual elements by simply passing the element name to each:

    $codes = $form->getErrors('username');
    $messages = $form->getMessages('username');

Note: When validating elements, Zend_Form sends a second argument to each element's isValid() method: the array of data being validated. This can then be used by individual validators to allow them to utilize other submitted values when determining the validity of the data. An example would be a registration form that requires both a password and password confirmation; the password element could use the password confirmation as part of its validation.

### Custom Error Messages

At times, you may want to specify one or more specific error messages to use instead of the error messages generated by the validators attached to your elements. Additionally, at times you may want to mark the form invalid yourself. This functionality is possible via the following methods.

- addErrorMessage($message): add an error message to display on form validation errors. You may call this more than once, and new messages are appended to the stack.

- addErrorMessages(array $messages): add multiple error messages to display on form validation errors.

- setErrorMessages(array $messages): add multiple error messages to display on form validation errors, overwriting all previously set error messages.

- getErrorMessages(): retrieve the list of custom error messages that have been defined.

- clearErrorMessages(): remove all custom error messages that have been defined.

- markAsError(): mark the form as having failed validation.

- addError($message): add a message to the custom error messages stack and flag the form as invalid.

- addErrors(array $messages): add several messages to the custom error messages stack and flag the form as invalid.

- setErrors(array $messages): overwrite the custom error messages stack with the provided messages and flag the form as invalid.

All errors set in this fashion may be translated.

### Retrieving Valid Values Only

There are scenarios when you want to allow your user to work on a valid form in several steps. Meanwhile you allow the user to save the form with any set of values inbetween. Then if all the data is specified you can transfer the model from the building or prototying stage to a valid stage.

You can retrieve all the valid values that match the submitted data by calling:

    $validValues = $form->getValidValues($_POST);

## Methods

The following is a full list of methods available to Zend_Form, grouped by type:

- Configuration and Options:

  - setOptions(array $options)

  - setConfig(Zend_Config $config)

- Plugin Loaders and paths:

  - setPluginLoader(Zend_Loader_PluginLoader_Interface $loader, $type = null)

  - getPluginLoader($type = null)

  - addPrefixPath($prefix, $path, $type = null)

  - addPrefixPaths(array $spec)

  - addElementPrefixPath($prefix, $path, $type = null)

  - addElementPrefixPaths(array $spec)

  - addDisplayGroupPrefixPath($prefix, $path)

- Metadata:

  - setAttrib($key, $value)

  - addAttribs(array $attribs)

  - setAttribs(array $attribs)

  - getAttrib($key)

  - getAttribs()

  - removeAttrib($key)

  - clearAttribs()

  - setAction($action)

  - getAction()

  - setMethod($method)

  - getMethod()

  - setName($name)

  - getName()

- Elements:

  - addElement($element, $name = null, $options = null)

  - addElements(array $elements)

  - setElements(array $elements)

  - getElement($name)

  - getElements()

  - removeElement($name)

  - clearElements()

  - setDefaults(array $defaults)

  - setDefault($name, $value)

  - getValue($name)

  - getValues()

  - getUnfilteredValue($name)

  - getUnfilteredValues()

  - setElementFilters(array $filters)

  - setElementDecorators(array $decorators)

- Sub forms:

  - addSubForm(Zend_Form $form, $name, $order = null)

  - addSubForms(array $subForms)

  - setSubForms(array $subForms)

  - getSubForm($name)

  - getSubForms()

  - removeSubForm($name)

  - clearSubForms()

  - setSubFormDecorators(array $decorators)

- Display groups:

  - addDisplayGroup(array $elements, $name, $options = null)

  - addDisplayGroups(array $groups)

  - setDisplayGroups(array $groups)

  - getDisplayGroup($name)

  - getDisplayGroups()

  - removeDisplayGroup($name)

  - clearDisplayGroups()

  - setDisplayGroupDecorators(array $decorators)

- Validation

  - populate(array $values)

  - isValid(array $data)

  - isValidPartial(array $data)

  - processAjax(array $data)

  - persistData()

  - getErrors($name = null)

  - getMessages($name = null)

- Rendering:

  - setView(Zend_View_Interface $view = null)

  - getView()

  - addDecorator($decorator, $options = null)

  - addDecorators(array $decorators)

  - setDecorators(array $decorators)

  - getDecorator($name)

  - getDecorators()

  - removeDecorator($name)

  - clearDecorators()

  - render(Zend_View_Interface $view = null)

- I18n:

  - setTranslator(Zend_Translate_Adapter $translator = null)

  - getTranslator()

  - setDisableTranslator($flag)

  - translatorIsDisabled()

## Configuration

Zend_Form is fully configurable via setOptions() and setConfig() (or by passing options or a Zend_Config object to the constructor). Using these methods, you can specify form elements, display groups, decorators, and metadata.

As a general rule, if 'set' + the option key refers to a Zend_Form method, then the value provided will be passed to that method. If the accessor does not exist, the key is assumed to reference an attribute, and will be passed to setAttrib().

Exceptions to the rule include the following:

- prefixPath will be passed to addPrefixPaths()

- elementPrefixPath will be passed to addElementPrefixPaths()

- displayGroupPrefixPath will be passed to addDisplayGroupPrefixPaths()

- the following setters cannot be set in this way:

  - setAttrib (though setAttribs *will* work)

  - setConfig

  - setDefault

  - setOptions

  - setPluginLoader

  - setSubForms

  - setTranslator

  - setView

As an example, here is a config file that passes configuration for every type of configurable data:

    [element]
    name = "registration"
    action = "/user/register"
    method = "post"
    attribs.class = "zend_form"
    attribs.onclick = "validate(this)"

    disableTranslator = 0

    prefixPath.element.prefix = "My_Element"
    prefixPath.element.path = "My/Element/"
    elementPrefixPath.validate.prefix = "My_Validate"
    elementPrefixPath.validate.path = "My/Validate/"
    displayGroupPrefixPath.prefix = "My_Group"
    displayGroupPrefixPath.path = "My/Group/"

    elements.username.type = "text"
    elements.username.options.label = "Username"
    elements.username.options.validators.alpha.validator = "Alpha"
    elements.username.options.filters.lcase = "StringToLower"
    ; more elements, of course...

    elementFilters.trim = "StringTrim"
    ;elementDecorators.trim = "StringTrim"

    displayGroups.login.elements.username = "username"
    displayGroups.login.elements.password = "password"
    displayGroupDecorators.elements.decorator = "FormElements"
    displayGroupDecorators.fieldset.decorator = "Fieldset"

    decorators.elements.decorator = "FormElements"
    decorators.fieldset.decorator = "FieldSet"
    decorators.fieldset.decorator.options.class = "zend_form"
    decorators.form.decorator = "Form"

The above could easily be abstracted to an XML or PHP array-based configuration file.

## Custom forms

An alternative to using configuration-based forms is to subclass Zend_Form. This has several benefits:

- You can unit test your form easily to ensure validations and rendering perform as expected.

- Fine-grained control over individual elements.

- Re-use of form objects, and greater portability (no need to track config files).

- Implementing custom functionality.

The most typical use case would be to use the init() method to setup specific form elements and configuration:

    class My_Form_Login extends Zend_Form
    {
        public function init()
        {
            $username = new Zend_Form_Element_Text('username');
            $username->class = 'formtext';
            $username->setLabel('Username:')
                     ->setDecorators(array(
                         array('ViewHelper',
                               array('helper' => 'formText')),
                         array('Label',
                               array('class' => 'label'))
                     ));

            $password = new Zend_Form_Element_Password('password');
            $password->class = 'formtext';
            $password->setLabel('Password:')
                     ->setDecorators(array(
                         array('ViewHelper',
                               array('helper' => 'formPassword')),
                         array('Label',
                               array('class' => 'label'))
                     ));

            $submit = new Zend_Form_Element_Submit('login');
            $submit->class = 'formsubmit';
            $submit->setValue('Login')
                   ->setDecorators(array(
                       array('ViewHelper',
                       array('helper' => 'formSubmit'))
                   ));

            $this->addElements(array(
                $username,
                $password,
                $submit
            ));

            $this->setDecorators(array(
                'FormElements',
                'Fieldset',
                'Form'
            ));
        }
    }

This form can then be instantiated with simply:

    $form = new My_Form_Login();

and all functionality is already setup and ready; no config files needed. (Note that this example is greatly simplified, as it contains no validators or filters for the elements.)

Another common reason for extension is to define a set of default decorators. You can do this by overriding the loadDefaultDecorators() method:

    class My_Form_Login extends Zend_Form
    {
        public function loadDefaultDecorators()
        {
            $this->setDecorators(array(
                'FormElements',
                'Fieldset',
                'Form'
            ));
        }
    }