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Peter WONG
3ddff676f8
I was (somehow) misled by the example, thinking `'1234'[2:]` outputs `34` because it `2:` mean copy the last 2 characters... This happens when you are in a hurry and didn't look into the text. Let makes it less ambiguous.
71 lines
2.0 KiB
ReStructuredText
71 lines
2.0 KiB
ReStructuredText
``slice``
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===========
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.. versionadded:: 1.6
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The slice filter was added in Twig 1.6.
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The ``slice`` filter extracts a slice of a sequence, a mapping, or a string:
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.. code-block:: jinja
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{% for i in [1, 2, 3, 4, 5]|slice(1, 2) %}
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{# will iterate over 2 and 3 #}
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{% endfor %}
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{{ '12345'|slice(1, 2) }}
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{# outputs 23 #}
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You can use any valid expression for both the start and the length:
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.. code-block:: jinja
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{% for i in [1, 2, 3, 4, 5]|slice(start, length) %}
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{# ... #}
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{% endfor %}
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As syntactic sugar, you can also use the ``[]`` notation:
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.. code-block:: jinja
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{% for i in [1, 2, 3, 4, 5][start:length] %}
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{# ... #}
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{% endfor %}
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{{ '12345'[1:2] }}
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{# you can omit the first argument -- which is the same as 0 #}
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{{ '12345'[:2] }} {# will display "12" #}
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{# you can omit the last argument -- which will select everything till the end #}
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{{ '12345'[2:] }} {# will display "345" #}
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The ``slice`` filter works as the `array_slice`_ PHP function for arrays and
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`substr`_ for strings.
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If the start is non-negative, the sequence will start at that start in the
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variable. If start is negative, the sequence will start that far from the end
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of the variable.
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If length is given and is positive, then the sequence will have up to that
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many elements in it. If the variable is shorter than the length, then only the
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available variable elements will be present. If length is given and is
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negative then the sequence will stop that many elements from the end of the
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variable. If it is omitted, then the sequence will have everything from offset
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up until the end of the variable.
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.. note::
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It also works with objects implementing the `Traversable`_ interface.
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Arguments
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---------
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* ``start``: The start of the slice
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* ``length``: The size of the slice
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* ``preserve_keys``: Whether to preserve key or not (when the input is an array)
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.. _`Traversable`: http://php.net/manual/en/class.traversable.php
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.. _`array_slice`: http://php.net/array_slice
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.. _`substr`: http://php.net/substr
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