Forms Rendering

The appearance of forms can be very diverse. In practice, we can encounter two extremes. On one hand, there is a need to render a series of forms in an application that are visually similar to each other, and we appreciate the easy rendering without a template using $form->render(). This is usually the case with administrative interfaces.

On the other hand, there are various forms where each one is unique. Their appearance is best described using HTML language in the template. And of course, in addition to both mentioned extremes, we will encounter many forms that fall somewhere in between.

Rendering With Latte

The Latte templating system fundamentally facilitates the rendering of forms and their elements. First, we'll show how to render forms manually, element by element, to gain full control over the code. Later we will show how to automate such rendering.

You can have the proposal of a Latte template for the form generated using the method Nette\Forms\Blueprint::latte($form), which will output it to the browser page. Then, you simply need to select the code with a click and copy it into your project.

`{control}`

The easiest way to render a form is to write in a template:

{control signInForm}

The look of the rendered form can be changed by configuring Renderer and individual controls.

`n:name`

It is extremely easy to link the form definition in PHP code with HTML code. Just add the n:name attributes. That's how easy it is!

protected function createComponentSignInForm(): Form
{
	$form = new Form;
	$form->addText('username')->setRequired();
	$form->addPassword('password')->setRequired();
	$form->addSubmit('send');
	return $form;
}

<form n:name=signInForm class=form>
	<div>
		<label n:name=username>Username: <input n:name=username size=20 autofocus></label>
	</div>
	<div>
		<label n:name=password>Password: <input n:name=password></label>
	</div>
	<div>
		<input n:name=send class="btn btn-default">
	</div>
</form>

The look of the resulting HTML code is entirely in your hands. If you use the n:name attribute with <select>, <button> or <textarea> elements, their internal content is automatically filled in. In addition, the <form n:name> tag creates a local variable $form with the drawn form object and the closing </form> draws all undrawn hidden elements (the same applies to {form} ... {/form}).

However, we must not forget to render possible error messages. Both those that were added to individual elements by the addError() method (using {inputError}) and those added directly to the form (returned by $form->getOwnErrors()):

<form n:name=signInForm class=form>
	<ul class="errors" n:ifcontent>
		<li n:foreach="$form->getOwnErrors() as $error">{$error}</li>
	</ul>

	<div>
		<label n:name=username>Username: <input n:name=username size=20 autofocus></label>
		<span class=error n:ifcontent>{inputError username}</span>
	</div>
	<div>
		<label n:name=password>Password: <input n:name=password></label>
		<span class=error n:ifcontent>{inputError password}</span>
	</div>
	<div>
		<input n:name=send class="btn btn-default">
	</div>
</form>

More complex form elements, such as RadioList or CheckboxList, can be rendered item by item:

{foreach $form[gender]->getItems() as $key => $label}
	<label n:name="gender:$key"><input n:name="gender:$key"> {$label}</label>
{/foreach}

`{label}` `{input}`

Don't you want to think for each element what HTML element to use for it in the template, whether <input>, <textarea> etc.? The solution is the universal {input} tag:

<form n:name=signInForm class=form>
	<ul class="errors" n:ifcontent>
		<li n:foreach="$form->getOwnErrors() as $error">{$error}</li>
	</ul>

	<div>
		{label username}Username: {input username, size: 20, autofocus: true}{/label}
		{inputError username}
	</div>
	<div>
		{label password}Password: {input password}{/label}
		{inputError password}
	</div>
	<div>
		{input send, class: "btn btn-default"}
	</div>
</form>

If the form uses a translator, the text inside the {label} tags will be translated.

Again, more complex form elements, such as RadioList or CheckboxList, can be rendered item by item:

{foreach $form[gender]->items as $key => $label}
	{label gender:$key}{input gender:$key} {$label}{/label}
{/foreach}

To render the <input> itself in the Checkbox item, use {input myCheckbox:}. HTML attributes must be separated by a comma {input myCheckbox:, class: required}.

`{inputError}`

Prints an error message for the form element, if it has one. The message is usually wrapped in an HTML element for styling. Avoiding rendering an empty element if there is no message can be elegantly done with n:ifcontent:

<span class=error n:ifcontent>{inputError $input}</span>

We can detect the presence of an error using the hasErrors() method and set the class of the parent element accordingly:

<div n:class="$form[username]->hasErrors() ? 'error'">
	{input username}
	{inputError username}
</div>

`{form}`

Tags {form signInForm}...{/form} are an alternative to <form n:name="signInForm">...</form>.

Automatic Rendering

With the {input} and {label} tags, we can easily create a generic template for any form. It will iterate and render all of its elements sequentially, except for hidden elements, which are rendered automatically when the form is terminated with the </form> tag. It will expect the name of the rendered form in the $form variable.

<form n:name=$form class=form>
	<ul class="errors" n:ifcontent>
		<li n:foreach="$form->getOwnErrors() as $error">{$error}</li>
	</ul>

	<div n:foreach="$form->getControls() as $input"
		n:if="$input->getOption(type) !== hidden">
		{label $input /}
		{input $input}
		{inputError $input}
	</div>
</form>

The used self-closing pair tags {label .../} show the labels coming from the form definition in the PHP code.

You can save this generic template in the basic-form.latte file and to render the form, just include it and pass the form name (or instance) to the $form parameter:

{include basic-form.latte, form: signInForm}

If you would like to influence the appearance of one particular form and draw one element differently, then the easiest way is to prepare blocks in the template that can be overwritten later. Blocks can also have dynamic names, so you can insert the name of the element to be drawn into them. For example:

...
	{label $input /}
	{block "input-{$input->name}"}{input $input}{/block}
...

For the element e.g. username this creates the block input-username, which can be easily overridden by using the tag {embed}:

{embed basic-form.latte, form: signInForm}
	{block input-username}
		<span class=important>
			{include parent}
		</span>
	{/block}
{/embed}

Alternatively, the entire contents of the basic-form.latte template can be defined as a block, including the $form parameter:

{define basic-form, $form}
	<form n:name=$form class=form>
		...
	</form>
{/define}

This will make it slightly easier to use:

{embed basic-form, signInForm}
	...
{/embed}

You only need to import the block in one place, at the beginning of the layout template:

{import basic-form.latte}

Special Cases

If you need to render only the inner part of the form without HTML tags <form>, for example when sending snippets, hide them using the n:tag-if attribute:

<form n:name=signInForm n:tag-if=false>
	<div>
		<label n:name=username>Username: <input n:name=username></label>
		{inputError username}
	</div>
</form>

Tag formContainer helps with rendering of inputs inside a form container.

<p>Which news you wish to receive:</p>

{formContainer emailNews}
<ul>
	<li>{input sport} {label sport /}</li>
	<li>{input science} {label science /}</li>
</ul>
{/formContainer}

Rendering Without Latte

The easiest way to render a form is to call:

$form->render();

The look of the rendered form can be changed by configuring Renderer and individual controls.

Manual Rendering

Each form element has methods that generate the HTML code for the form field and label. They can return it as either a string or a Nette\Utils\Html object:

getControl(): Html|string returns the HTML code of the element
getLabel($caption = null): Html|string|null returns the HTML code of the label, if any

This allows the form to be rendered element by element:

<?php $form->render('begin') ?>
<?php $form->render('errors') ?>

<div>
	<?= $form['name']->getLabel() ?>
	<?= $form['name']->getControl() ?>
	<span class=error><?= htmlspecialchars($form['name']->getError()) ?></span>
</div>

<div>
	<?= $form['age']->getLabel() ?>
	<?= $form['age']->getControl() ?>
	<span class=error><?= htmlspecialchars($form['age']->getError()) ?></span>
</div>

// ...

<?php $form->render('end') ?>

While for some elements getControl() returns a single HTML element (e.g. <input>, <select> etc.), for others it returns a whole piece of HTML code (CheckboxList, RadioList). In this case, you can use methods that generate individual inputs and labels, for each item separately:

getControlPart($key = null): ?Html returns the HTML code of a single item
getLabelPart($key = null): ?Html returns the HTML code for the label of a single item

These methods are prefixed with get for historical reasons, but generate would be better, as it creates and returns a new Html element on each call.

Renderer

It is an object that provides rendering of the form. It can be set by the $form->setRenderer method. It is passed control when the $form->render() method is called.

If we don't set a custom renderer, the default renderer Nette\Forms\Rendering\DefaultFormRenderer will be used. This will render the form elements as an HTML table. The output looks like this:

<table>
<tr class="required">
	<th><label class="required" for="frm-name">Name:</label></th>

	<td><input type="text" class="text" name="name" id="frm-name" required value=""></td>
</tr>

<tr class="required">
	<th><label class="required" for="frm-age">Age:</label></th>

	<td><input type="text" class="text" name="age" id="frm-age" required value=""></td>
</tr>

<tr>
	<th><label>Gender:</label></th>
	...

It's up to you, whether to use a table or not, and many web designers prefer different markups, for example a list. We may configure DefaultFormRenderer so it would not render into a table at all. We just have to set proper $wrappers. The first index always represents an area and the second one it's element. All respective areas are shown in the picture:

By default a group of controls is wrapped in <table>, and every pair is a table row <tr> containing a pair of label and control (cells <th> and <td>). Let's change all those wrapper elements. We will wrap controls into <dl>, leave pair by itself, put label into <dt> and wrap control into <dd>:

$renderer = $form->getRenderer();
$renderer->wrappers['controls']['container'] = 'dl';
$renderer->wrappers['pair']['container'] = null;
$renderer->wrappers['label']['container'] = 'dt';
$renderer->wrappers['control']['container'] = 'dd';

$form->render();

Results into the following snippet:

<dl>
	<dt><label class="required" for="frm-name">Name:</label></dt>

	<dd><input type="text" class="text" name="name" id="frm-name" required value=""></dd>


	<dt><label class="required" for="frm-age">Age:</label></dt>

	<dd><input type="text" class="text" name="age" id="frm-age" required value=""></dd>


	<dt><label>Gender:</label></dt>
	...
</dl>

Wrappers can affect many attributes. For example:

add special CSS classes to each form input
distinguish between odd and even lines
make required and optional draw differently
set, whether error messages are shown above the form or close to each element

Options

The behavior of Renderer can also be controlled by setting options on individual form elements. This way you can set the tooltip that is displayed next to the input field:

$form->addText('phone', 'Number:')
	->setOption('description', 'This number will remain hidden');

If we want to place HTML content into it, we use Html class.

use Nette\Utils\Html;

$form->addText('phone', 'Phone:')
	->setOption('description', Html::el('p')
		->setHtml('<a href="...">Terms of service.</a>')
	);

Html element can be also used instead of label: $form->addCheckbox('conditions', $label).

Grouping Inputs

Renderer allows to group elements into visual groups (fieldsets):

$form->addGroup('Personal data');

Creating new group activates it – all elements added further are added to this group. You may build a form like this:

$form = new Form;
$form->addGroup('Personal data');
$form->addText('name', 'Your name:');
$form->addInteger('age', 'Your age:');
$form->addEmail('email', 'Email:');

$form->addGroup('Shipping address');
$form->addCheckbox('send', 'Ship to address');
$form->addText('street', 'Street:');
$form->addText('city', 'City:');
$form->addSelect('country', 'Country:', $countries);

The renderer draws groups first and then elements that do not belong to any group.

Bootstrap Support

You can find examples of configuration of Renderer for Twitter Bootstrap 2, Bootstrap 3 and Bootstrap 4

HTML Attributes

To set arbitrary HTML attributes for form elements, use the method setHtmlAttribute(string $name, $value = true):

$form->addInteger('number', 'Number:')
	->setHtmlAttribute('class', 'big-number');

$form->addSelect('rank', 'Order by:', ['price', 'name'])
	->setHtmlAttribute('onchange', 'submit()'); // calls JS function submit() on change


// To set attributes of the <form> itself
$form->setHtmlAttribute('id', 'myForm');

Specifying the type of element:

$form->addText('tel', 'Your telephone:')
	->setHtmlType('tel')
	->setHtmlAttribute('placeholder', 'Please, fill in your telephone');

Setting the type and other attributes serves only for visual purposes. Verification of input correctness must occur on the server, which you can ensure by choosing an appropriate form control and specifying validation rules.

For individual items in radio or checkbox lists, we can set an HTML attribute with different values for each of them. Notice the colon after style:, which ensures the value is selected based on the key:

$colors = ['r' => 'red', 'g' => 'green', 'b' => 'blue'];
$styles = ['r' => 'background:red', 'g' => 'background:green'];
$form->addCheckboxList('colors', 'Colors:', $colors)
	->setHtmlAttribute('style:', $styles);

Renders:

<label><input type="checkbox" name="colors[]" style="background:red" value="r">red</label>
<label><input type="checkbox" name="colors[]" style="background:green" value="g">green</label>
<label><input type="checkbox" name="colors[]" value="b">blue</label>

For setting boolean attributes, such as readonly, we can use the notation with a question mark:

$form->addCheckboxList('colors', 'Colors:', $colors)
	->setHtmlAttribute('readonly?', 'r'); // use array for multiple keys, e.g. ['r', 'g']

Renders:

<label><input type="checkbox" name="colors[]" readonly value="r">red</label>
<label><input type="checkbox" name="colors[]" value="g">green</label>
<label><input type="checkbox" name="colors[]" value="b">blue</label>

For selectboxes, the setHtmlAttribute() method sets the attributes of the <select> element. If we want to set the attributes for each <option>, we will use the method setOptionAttribute(). Also, the colon and question mark used above work:

$form->addSelect('colors', 'Colors:', $colors)
	->setOptionAttribute('style:', $styles);

Renders:

<select name="colors">
	<option value="r" style="background:red">red</option>
	<option value="g" style="background:green">green</option>
	<option value="b">blue</option>
</select>

Prototypes

An alternative way to set HTML attributes is to modify the template from which the HTML element is generated. The template is an Html object and is returned by the getControlPrototype() method:

$input = $form->addInteger('number');
$html = $input->getControlPrototype(); // <input>
$html->class('big-number');            // <input class="big-number">

The label template returned by getLabelPrototype() can also be modified in this way:

$html = $input->getLabelPrototype(); // <label>
$html->class('distinctive');         // <label class="distinctive">

For Checkbox, CheckboxList and RadioList items you can influence the element template that wraps the item. It is returned by getContainerPrototype(). By default it is an “empty” element, so nothing is rendered, but by giving it a name it will be rendered:

$input = $form->addCheckbox('send');
$html = $input->getContainerPrototype();
$html->setName('div'); // <div>
$html->class('check'); // <div class="check">
echo $input->getControl();
// <div class="check"><label><input type="checkbox" name="send"></label></div>

In the case of CheckboxList and RadioList it is also possible to influence the item separator pattern returned by the method getSeparatorPrototype(). By default, it is an element <br>. If you change it to a pair element, it will wrap the individual items instead of separating them. It is also possible to influence the HTML element template of the item labels, which returns getItemLabelPrototype().

Translating

If you are programming a multilingual application, you will probably need to render the form in different languages. The Nette Framework defines a translation interface for this purpose Nette\Localization\Translator. There is no default implementation in Nette, you can choose according to your needs from several ready-made solutions you can find on Componette. Their documentation tells you how to configure the translator.

The form supports outputting text through the translator. We pass it using the setTranslator() method:

$form->setTranslator($translator);

From now on, not only all labels, but also all error messages or select box entries will be translated into another language.

It is possible to set a different translator for individual form elements or to disable translation completely with null:

$form->addSelect('carModel', 'Model:', $cars)
	->setTranslator(null);

For validation rules, specific parameters are also passed to the translator, for example for rule:

$form->addPassword('password', 'Password:')
	->addRule($form::MinLength, 'Password has to be at least %d characters long', 8)

the translator is called with the following parameters:

$translator->translate('Password has to be at least %d characters long', 8);

and thus can choose the correct plural form for the word characters by count.

Event onRender

Just before the form is rendered, we can have our code invoked. This can, for example, add HTML classes to the form elements for proper display. We add the code to the onRender array:

$form->onRender[] = function ($form) {
	BootstrapCSS::initialize($form);
};

Forms Rendering

Rendering With Latte

{control}

n:name

{label} {input}

{inputError}

{form}

Automatic Rendering

Special Cases

Rendering Without Latte

Manual Rendering

Renderer

Options

Grouping Inputs

Bootstrap Support

HTML Attributes

Prototypes

Translating

Event onRender

`{control}`

`n:name`

`{label}` `{input}`

`{inputError}`

`{form}`