How pass @index as parameter to custom helper

[diosney]

Setup:

- A custom helper content that expects two parameters a collection and an index.

- An #each helper invocation that calls to #content helper, like this:

{{#each data}} {{#content ../parent_options @index}}{{/content}} {{/each}}

The issue:

Inside the content helper definition I want to access the @index value, say 0,1,2,... but I'm only getting a string!

How can pass as a parameter and access inside the content helper definition the value of @index?

[diosney]

StackOverflow question here: http://stackoverflow.com/questions/19750003/handlebars-how-pass-index-as-parameter-to-custom-helper, just in case if you want to answer there too :D

[diosney]

On this, what I'm trying to accomplish ultimately is to write a helper that gets as parameter an object and a index, and returns object[index](somesort,, is a little more complex than that).

Can you help me to write such a helper with Handlebars.PHP?

Thanks in advance.

[everplays]

handlebars.php doesn't parse arguments of helpers, it's your job to parse and give meaning to them (I'm talking about third parameter that gets passed to helpers, _helper_each($template, $context, $args, $source)). but in your case, there's no need to parse arguments, you can simply access it by $context->lastIndex().

[boukeversteegh]

You need to parse the arguments manually inside a helper.

$hdlbars = new Handlebars_Engine();

$hdlbars->getHelpers()->add('content', function($template, $context, $args, $source) {
    $args = explode(' ', $args);

    foreach( $args as &$arg ) {
        if( $arg == '@index' ) {
            $arg = $context->lastIndex();
        } else {
            // Parse variable name.
            $arg = $context->get($arg);
        }
    }

    $buffer = "arguments passed: " . implode(', ' $args);
    $buffer .= $template->render($context);
    return $buffer;
});

[diosney]

@everplays, @boukeversteegh:

1001 Thanks! With your help I was able to do the custom helper!

This was the final implementation, just for the record.

 /**
         * Handlebars Helper Content. Return object->Alphabet[index].
         *
         * @param $template
         * @param $context
         * @param $args
         * @param $source
         *
         * @return Handlebars_String
         * @throws InvalidArgumentException
         */
        public static function _helper_content($template, $context, $args, $source) {
            $Alphabet = range('A', 'Z');

            $tmp = explode(' ', $args);
            $buffer = '';

            $object = $context->get($tmp[0]);

            if (count($tmp) < 2 || $tmp[1] == '@index') {
                $last_index = $context->lastIndex();
                $letter = $Alphabet[$last_index];
            }
            else {
                $index = $context->get($tmp[1]);
                $letter = $Alphabet[$index];
            }

            $buffer .= $object->$letter;

            return new Handlebars_String($buffer);
        }

[cgray]

Possibly a more holistic solution would be to update the Context::get to handle the the case of @index and @key specifically as I did here

[jslegers]

For those interested, here's a way to create powerful templates with custom helpers, while still using but a minimal amount of code :

Template table.hbs :

{{#if table}}
<table>
    <thead>
        <tr>
            <th style="width: 2%;">#</th>
            {{#each table.0}}
            <th nowrap="nowrap">
                {{uppercase @key}}
            </th>
            {{/each}}
        </tr>
    </thead>
    <tbody>
        {{#each table}}
        <tr> 
            <th>{{increment @index}}</th>
            {{#each this}}
            <td><input type="text" value="{{this}}" /></td>
            {{/each}}
        </tr>
        {{/each}}
    </tbody>
</table>
{{#if paginator}}
<nav class="pagination">
    <ul>
        {{#each paginator}}
        <li><a href="{{this}}">{{@key}}</a></li>
        {{/each}}
    </ul>
</nav>
{{/if}}
{{else}}
<p>No data found!</p>
{{/if}}

The view :

// Create handlebars object
$template_engine = new \Handlebars\Handlebars;

// Get helpers object
$helpers = $template_engine->getHelpers();

// Add 'uppercase' helper
$helpers->add('uppercase', function($template, $context, $args, $source) {
    return ucwords($context->get($args));
});

// Add 'increment' helper
$helpers->add('increment', function($template, $context, $args, $source) {
    return $context->get($args) + 1;
});

// Render template
echo $template_engine->render(file_get_contents(__DIR__ . '/table.hbs'), array(
    'table' => array(
        array('name' => 'John', 'profession' => 'programmer', 'city' => 'Leuven'),
        array('name' => 'Sam', 'profession' => 'designer', 'city' => 'Aarschot'),
        array('name' => 'Tom', 'profession' => 'owner', 'city' => 'Leuven'),
        array('name' => 'Steve', 'profession' => 'copywriter', 'city' => 'Brussels'),
        array('name' => 'Thomas', 'profession' => 'designer', 'city' => 'Antwerp')
    ),
    'paginator' => array(
        'first' => 'http://www.test.com/first',
        '1' => 'http://www.test.com/1',
        '2' => 'http://www.test.com/2',
        '3' => 'http://www.test.com/3',
        'last' => 'http://www.test.com/last'
    )
));

The output :

<table>
    <thead>
        <tr>
            <th style="width: 2%;">#</th>
            <th nowrap="nowrap">
                Name
            </th>
            <th nowrap="nowrap">
                Profession
            </th>
            <th nowrap="nowrap">
                City
            </th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <th>1</th>
            <td><input type="text" value="John" /></td>
            <td><input type="text" value="programmer" /></td>
            <td><input type="text" value="Leuven" /></td>
        </tr>
        <tr>
            <th>2</th>
            <td><input type="text" value="Sam" /></td>
            <td><input type="text" value="designer" /></td>
            <td><input type="text" value="Aarschot" /></td>
        </tr>
        <tr>
            <th>3</th>
            <td><input type="text" value="Tom" /></td>
            <td><input type="text" value="owner" /></td>
            <td><input type="text" value="Leuven" /></td>
        </tr>
        <tr>
            <th>4</th>
            <td><input type="text" value="Steve" /></td>
            <td><input type="text" value="copywriter" /></td>
            <td><input type="text" value="Brussels" /></td>
        </tr>
        <tr>
            <th>5</th>
            <td><input type="text" value="Thomas" /></td>
            <td><input type="text" value="designer" /></td>
            <td><input type="text" value="Antwerp" /></td>
        </tr>
    </tbody>
</table>
<nav class="pagination">
    <ul>
        <li><a href="http://www.test.com/first">first</a></li>
        <li><a href="http://www.test.com/1">1</a></li>
        <li><a href="http://www.test.com/2">2</a></li>
        <li><a href="http://www.test.com/3">3</a></li>
        <li><a href="http://www.test.com/last">last</a></li>
    </ul>
</nav>

See also :

• http://stackoverflow.com/questions/19750003/handlebars-how-pass-index-as-parameter-to-custom-helper/24531300#24531300