Latte Filters

Filters are functions that change or format the data to a form we want. This is summary of the built-in filters which are available.

String or array transformation
`truncate` `(length, append = '…')`	shortens the length preserving whole words
`substr` `(offset [, length])`	returns part of the string
`trim` `(charset = whitespace)`	strips whitespace or other characters from the beginning and end of the string
`stripHtml`	removes HTML tags and converts HTML entities to text
`strip`	removes whitespace, similar to spaceless tag
`indent` `(level = 1, char = "\t")`	indents the text from left with number of tabs
`replace` `(search, replace = '')`	replaces all occurrences of the search string with the replacement
`replaceRE` `(pattern, replace = '')`	replaces all occurrences according to regular expression
`padLeft` `(length, pad = ' ')`	completes the string to given length from left
`padRight` `(length, pad = ' ')`	completes the string to given length from right
`repeat` `(count)`	repeats the string
`implode` `(glue = '')`	joins an array to a string
`webalize`	adjusts the UTF-8 string to the shape used in the URL
`breakLines`	Inserts HTML line breaks before all newlines
`reverse`	reverse an UTF-8 string or array
`length`	returns length of a string or array
`batch` `(array, length [, item])`	listing linear data in a table

Letter casing
`lower`	makes a string lower case
`upper`	makes a string upper case
`firstUpper`	makes the first letter upper case
`capitalize`	lower case, the first letter of each word upper case

Formatting
`date` `(format)`	formats date
`number` `(decimals = 0, decPoint = '.')`	format number
`bytes` `(precision = 2)`	formats size in bytes
`dataStream` `(mimetype = detect)`	Data URI protocol conversion

Escaping
`noescape`	prints a variable without escaping
`escapeUrl`	escapes parameter in URL

There are also escaping filters for HTML (escapeHtml and escapeHtmlComment), XML (escapeXml), JavaScript (escapeJs), CSS (escapeCss) and iCalendar (escapeICal), which Latte uses itself thanks to context-aware escaping and you do not need to write them.

Security
`noCheck`	prevents automatic URL sanitization
`checkUrl`	sanitizes string for use inside href attribute

Latte the src and href attributes checks automatically, so you almost don't need to use the checkUrl filter.

All built-in filters work with UTF-8 encoded strings.

Usage

Latte allows calling filters by using the pipe sign notation called modifier (preceding space is allowed):

<h1>{$heading|upper}</h1>

Filters can be chained, in that case they apply in order from left to right:

<h1>{$heading|lower|capitalize}</h1>

Parameters are put after the filter name separated by colon or comma:

<h1>{$heading|truncate:20,''}</h1>

Filters can be applied on expression:

{var $name = ($title|upper) . ($subtitle|lower)}</h1>

Custom filters can be registered this way:

$latte = new Latte\Engine;
$latte->addFilter('shortify', function (string $s, int $len = 10): string {
	return mb_substr($s, 0, $len);
});

We use it in a template like this:

<p>{$text|shortify}</p>
<p>{$text|shortify:100}</p>

truncate

Shortens a string to the maximum given length but tries to preserve whole words. If the string is truncated it adds ellipsis at the end (this can be changed by the second parameter).

{var $title = 'Hello, how are you?'}
{$title|truncate:5} Hell…
{$title|truncate:17} Hello, how are…
{$title|truncate:30} Hello, how are you?

strip

Removes unnecessary whitespace from the output.

{block |strip}
	<ul>
		<li>Hello</li>
	</ul>
{/block}

Generates

<ul> <li>Hello</li> </ul>

indent

Indents a text from left by a given number of tabs or other characters which we specify in the second optional argument:

<div>
{block |indent}
<p>Hello</p>
{/block}
</div>

Generates

<div>
	<p>Hello</p>
</div>

webalize

The filter removes the diacritics and replaces all the characters except the letters of the English alphabet and digits by a hyphen. Requires the installation of nette/utils.

{var $s = 'Our 10. product'}
{$s|webalize} our-10-product

breakLines

Inserts HTML line breaks before all newlines. Input text is automatically escaped.

{var $s = "Text & with \n newline"}
{$s|breakLines} "Text &amp; with <br>\n newline"

reverse

{var $s = 'Nette'}
{$s|reverse} etteN
{var $a = ['N', 'e', 't', 't', 'e']}
{$a|reverse} ['e', 't', 't', 'e', 'N']

Letter casing

{var $s = 'blue COLOR'}
{$s|lower} blue color
{$s|upper} BLUE COLOR
{$s|firstUpper} Blue COLOR
{$s|capitalize} Blue Color

date

Returns a date in the given format using options of strftime or date PHP functions. Filter gets a date as a UNIX timestamp, a string or an object of DateTime type.

{$today|date:'%d.%m.%Y'}

number

Formats a number to given number of decimal places. You can also specify a character of the decimal point and thousands separator.

{1234.20 |number}  1,234
{1234.20 |number:1}  1,234.2
{1234.20 |number:2}  1,234.20
{1234.20 |number:2:',':' '}  1 234,20

bytes

Formats a size in bytes to human-readable form.

{$size|bytes} 0 B, 10 B or 1.25 GB, …

dataStream

Converts the data to URI scheme. With this filter you can insert images to HTML or CSS without linking external files. All the modern browsers. Requires PHP extension fileinfo.

Lets have an image in a variable $img = Image::fromFile('obrazek.gif'), then

<img src="{$img|dataStream}">

generates for example:

<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA
AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
9TXL0Y4OHwAAAABJRU5ErkJggg==">

batch

Simplifies the listing of linear data into a table. The first parameter is the number of columns, the second (optional) additional value to fill the last row.

{var $items = ['a', 'b', 'c', 'd', 'e', 'f', 'g']}
<table>
{foreach ($items|batch:3:'No item') as $row}
    <tr>
        {foreach $row as $column}
            <td>{$column}</td>
        {/foreach}
    </tr>
{/foreach}
</table>

generates:

<table>
    <tr>
        <td>a</td>
        <td>b</td>
        <td>c</td>
    </tr>
    <tr>
        <td>d</td>
        <td>e</td>
        <td>f</td>
    </tr>
    <tr>
        <td>g</td>
        <td>No item</td>
        <td>No item</td>
    </tr>
</table>

escapeUrl

Escapes a variable to be used as a parameter in URL.

<a href="http://example.com/{$name|escapeUrl}">{$name}</a>

noCheck

Prevents automatic URL sanitization. Latte automatically checks if the variable contains a web URL (ie. HTTP protocol) and prevents the writing of links that may pose a security risk.

If the link uses a different scheme, such as javascript: or data:, and you are sure of its contents, you can disable the check via |noCheck.

{var $link = 'javascript:window.close()'}

<a href="{$link}">checked</a>
<a href="{$link|noCheck}">unchecked</a>

Generates:

<a href="">checked</a>
<a href="javascript:window.close()">unchecked</a>

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