我们从Python开源项目中，提取了以下50个代码示例，用于说明如何使用jinja2.runtime.Undefined()。
def do_default(value, default_value=u'', boolean=False): """If the value is undefined it will return the passed default value, otherwise the value of the variable: .. sourcecode:: jinja {{ my_variable|default('my_variable is not defined') }} This will output the value of ``my_variable`` if the variable was defined, otherwise ``'my_variable is not defined'``. If you want to use default with variables that evaluate to false you have to set the second parameter to `true`: .. sourcecode:: jinja {{ ''|default('the string was empty', true) }} """ if isinstance(value, Undefined) or (boolean and not value): return default_value return value
def _environment_sanity_check(environment): """Perform a sanity check on the environment.""" assert issubclass(environment.undefined, Undefined), 'undefined must ' \ 'be a subclass of undefined because filters depend on it.' assert environment.block_start_string != \ environment.variable_start_string != \ environment.comment_start_string, 'block, variable and comment ' \ 'start strings must be different' assert environment.newline_sequence in ('\r', '\r\n', '\n'), \ 'newline_sequence set to unknown line ending string.' return environment
def __new__(cls, source, block_start_string=BLOCK_START_STRING, block_end_string=BLOCK_END_STRING, variable_start_string=VARIABLE_START_STRING, variable_end_string=VARIABLE_END_STRING, comment_start_string=COMMENT_START_STRING, comment_end_string=COMMENT_END_STRING, line_statement_prefix=LINE_STATEMENT_PREFIX, line_comment_prefix=LINE_COMMENT_PREFIX, trim_blocks=TRIM_BLOCKS, lstrip_blocks=LSTRIP_BLOCKS, newline_sequence=NEWLINE_SEQUENCE, keep_trailing_newline=KEEP_TRAILING_NEWLINE, extensions=(), optimized=True, undefined=Undefined, finalize=None, autoescape=False): env = get_spontaneous_environment( block_start_string, block_end_string, variable_start_string, variable_end_string, comment_start_string, comment_end_string, line_statement_prefix, line_comment_prefix, trim_blocks, lstrip_blocks, newline_sequence, keep_trailing_newline, frozenset(extensions), optimized, undefined, finalize, autoescape, None, 0, False, None) return env.from_string(source, template_class=cls)
def __call__(self, *args, **kwargs): context = self._template.new_context(dict(*args, **kwargs)) consume(self._template.root_render_func(context)) rv = context.vars['result'] if self._undefined_to_none and isinstance(rv, Undefined): rv = None return rv
def do_xmlattr(_eval_ctx, d, autospace=True): """Create an SGML/XML attribute string based on the items in a dict. All values that are neither `none` nor `undefined` are automatically escaped: .. sourcecode:: html+jinja <ul{{ {'class': 'my_list', 'missing': none, 'id': 'list-%d'|format(variable)}|xmlattr }}> ... </ul> Results in something like this: .. sourcecode:: html <ul class="my_list" id="list-42"> ... </ul> As you can see it automatically prepends a space in front of the item if the filter returned something unless the second parameter is false. """ rv = u' '.join( u'%s="%s"' % (escape(key), escape(value)) for key, value in iteritems(d) if value is not None and not isinstance(value, Undefined) ) if autospace and rv: rv = u' ' + rv if _eval_ctx.autoescape: rv = Markup(rv) return rv
def test_defined(value): """Return true if the variable is defined: .. sourcecode:: jinja {% if variable is defined %} value of variable: {{ variable }} {% else %} variable is not defined {% endif %} See the :func:`default` filter for a simple way to set undefined variables. """ return not isinstance(value, Undefined)
def test_undefined(value): """Like :func:`defined` but the other way round.""" return isinstance(value, Undefined)
def is_undefined(obj): """Check if the object passed is undefined. This does nothing more than performing an instance check against :class:`Undefined` but looks nicer. This can be used for custom filters or tests that want to react to undefined variables. For example a custom default filter can look like this:: def default(var, default=''): if is_undefined(var): return default return var """ from jinja2.runtime import Undefined return isinstance(obj, Undefined)
def fail_for_missing_callable(string, name): msg = string % name if isinstance(name, Undefined): try: name._fail_with_undefined_error() except Exception as e: msg = '%s (%s; did you forget to quote the callable name?)' % (msg, e) raise TemplateRuntimeError(msg)
def __new__(cls, source, block_start_string=BLOCK_START_STRING, block_end_string=BLOCK_END_STRING, variable_start_string=VARIABLE_START_STRING, variable_end_string=VARIABLE_END_STRING, comment_start_string=COMMENT_START_STRING, comment_end_string=COMMENT_END_STRING, line_statement_prefix=LINE_STATEMENT_PREFIX, line_comment_prefix=LINE_COMMENT_PREFIX, trim_blocks=TRIM_BLOCKS, lstrip_blocks=LSTRIP_BLOCKS, newline_sequence=NEWLINE_SEQUENCE, keep_trailing_newline=KEEP_TRAILING_NEWLINE, extensions=(), optimized=True, undefined=Undefined, finalize=None, autoescape=False, enable_async=False): env = get_spontaneous_environment( block_start_string, block_end_string, variable_start_string, variable_end_string, comment_start_string, comment_end_string, line_statement_prefix, line_comment_prefix, trim_blocks, lstrip_blocks, newline_sequence, keep_trailing_newline, frozenset(extensions), optimized, undefined, finalize, autoescape, None, 0, False, None, enable_async) return env.from_string(source, template_class=cls)
