gluon/docs/dev/web/view.rst
2017-02-22 01:32:19 +01:00

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Views
=====
The template parser reads views from ``/lib/gluon/web/view``. Writing own view
should be avoided in favour of using :doc:`model` with their predefined views.
Views are partial HTML pages, with additional template tags that allow
to embed Lua code and translation strings. The following tags are defined:
- ``<%`` ... ``%>`` evaluates the enclosed Lua expression.
- ``<%=`` ... ``%>`` evaluates the enclosed Lua expression and prints its value.
- ``<%+`` ... ``%>`` includes another template.
- ``<%:`` ... ``%>`` translates the enclosed string using the loaded i18n catalog.
- ``<%_`` ... ``%>`` translates the enclosed string *without escaping HTML entities*
in the translation. This only makes sense when the i18n catalog contains HTML code.
- ``<%#`` ... ``%>`` is a comment.
All of these also come in the whitespace-stripping variants ``<%-`` and ``-%>`` that
remove all whitespace before or after the tag.
Complex combinations of HTML and Lua code are possible, for example:
.. code-block:: text
<div>
<% if foo then %>
Content
<% end %>
</div>
Variables and functions
-----------------------
Many call sites define additional variables (for example, model templates can
access the model as *self* and an unique element ID as *id*), but the following
variables and functions should always be available for the embedded Lua code:
- *renderer*: :ref:`web-controller-template-renderer`
- *http*: :ref:`web-controller-http`
- *request*: Table containing the path components of the current page
- *url* (*path*): returns the URL for the given path, which is passed as a table of path components.
- *attr* (*key*, *value*): Returns a string of the form ``key="value"``
(with a leading space character before the key).
*value* is converted to a string (tables are serialized as JSON) and HTML entities
are escaped. Returns an empty string when *value* is *nil* or *false*.
- *include* (*template*): Includes another template.
- *node* (*path*, ...): Returns the controller node for the given page (passed as
one argument per path component).
Use ``node(unpack(request))`` to get the node for the current page.
- *pcdata* (*str*): Escapes HTML entities in the passed string.
- *urlencode* (*str*): Escapes the passed string for use in an URL.
- *translate* and *translatef*: see :doc:`i18n`