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Dynamic data is a plain associative array passed as the second argument to any render method (or under dynamicData in the render() options array).

Structure

$dynamicData = [
    'merge_tags' => [       // optional
        'text' => [/* paragraph, heading, button text */],
        'url'  => [/* href, src, image URLs */],
        'attr' => [/* alt, aria-label, etc. */],
    ],
    'context' => [/* string|int|float|bool values */], // optional
];

All fields are optional — include only what your template uses.

Merge tags

text — inline content

$client->renderHtml('template-id', [
    'merge_tags' => [
        'text' => [
            'name'       => 'Noruwa',
            'company'    => 'Maildeno',
            'reset_name' => 'Password',
        ],
    ],
]);

Values are HTML-escaped before insertion.

url — links and image sources

$client->renderHtml('template-id', [
    'merge_tags' => [
        'url' => [
            'reset_url'    => 'https://app.example.com/reset/abc123',
            'banner_image' => 'https://cdn.example.com/banner.jpg',
        ],
    ],
]);

Values are URL percent-encoded before insertion.

attr — HTML attributes

$client->renderHtml('template-id', [
    'merge_tags' => [
        'attr' => ['alt_text' => 'Product banner'],
    ],
]);

Values are HTML attribute-safe encoded.

Context

$client->renderHtml('template-id', [
    'context' => [
        'plan'    => 'pro',
        'country' => 'usa',
        'age'     => 25,
    ],
]);

Context values drive visibility rules and are never rendered into content.

Full example

$client->render([
    'templateId'  => '550e8400-e29b-41d4-a716-446655440000',
    'target'      => 'mjml',
    'dynamicData' => [
        'merge_tags' => [
            'text' => [
                'name'       => 'Noruwa',
                'company'    => 'Maildeno',
                'reset_name' => 'Password',
            ],
            'url' => [
                'reset_url' => 'https://app.example.com/reset/abc123',
            ],
            'attr' => [
                'alt_text' => 'Cave image',
            ],
        ],
        'context' => [
            'country'      => 'usa',
            'country_rank' => '2',
            'expiry'       => '2028',
        ],
    ],
]);

Missing and extra values

  • A merge tag in the template with no supplied value renders as an empty string.

  • A supplied value for a tag not present in the template is silently ignored.

  • Context keys not matched by any visibility rule are silently ignored.

These rules live in the maildeno-engine renderer itself, so they’re identical whether it’s running as the JS/Python SDKs' embedded Wasm module or as PHP’s native subprocess. See Merge Tags and Visibility Rules for the builder-side documentation.