``merge`` ========= The ``merge`` filter merges an array with another array: .. code-block:: jinja {% set values = [1, 2] %} {% set values = values|merge(['apple', 'orange']) %} {# values now contains [1, 2, 'apple', 'orange'] #} New values are added at the end of the existing ones. The ``merge`` filter also works on hashes: .. code-block:: jinja {% set items = { 'apple': 'fruit', 'orange': 'fruit', 'peugeot': 'unknown' } %} {% set items = items|merge({ 'peugeot': 'car', 'renault': 'car' }) %} {# items now contains { 'apple': 'fruit', 'orange': 'fruit', 'peugeot': 'car', 'renault': 'car' } #} For hashes, the merging process occurs on the keys: if the key does not already exist, it is added but if the key already exists, its value is overridden. .. tip:: If you want to ensure that some values are defined in an array (by given default values), reverse the two elements in the call: .. code-block:: jinja {% set items = { 'apple': 'fruit', 'orange': 'fruit' } %} {% set items = { 'apple': 'unknown' }|merge(items) %} {# items now contains { 'apple': 'fruit', 'orange': 'fruit' } #} .. note:: Internally, Twig uses the PHP `array_merge`_ function. It supports Traversable objects by transforming those to arrays. .. _`array_merge`: http://php.net/array_merge