jinja2.meta Namespace Reference

Classes
class	TrackingCodeGenerator

Functions
t.Set[str]	find_undeclared_variables (nodes.Template ast)
t.Iterator[t.Optional[str]]	find_referenced_templates (nodes.Template ast)

Variables
tuple	_ref_types = (nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include)
	_RefType = t.Union[nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include]

Detailed Description

Functions that expose information about templates that might be
interesting for introspection.

Function Documentation

find_referenced_templates()

t.Iterator[t.Optional[str]] jinja2.meta.find_referenced_templates

(

nodes.Template

ast

)

Finds all the referenced templates from the AST.  This will return an
iterator over all the hardcoded template extensions, inclusions and
imports.  If dynamic inheritance or inclusion is used, `None` will be
yielded.

>>> from jinja2 import Environment, meta
>>> env = Environment()
>>> ast = env.parse('{% extends "layout.html" %}{% include helper %}')
>>> list(meta.find_referenced_templates(ast))
['layout.html', None]

This function is useful for dependency tracking.  For example if you want
to rebuild parts of the website after a layout template has changed.

find_undeclared_variables()

t.Set[str] jinja2.meta.find_undeclared_variables

(

nodes.Template

ast

)

Returns a set of all variables in the AST that will be looked up from
the context at runtime.  Because at compile time it's not known which
variables will be used depending on the path the execution takes at
runtime, all variables are returned.

>>> from jinja2 import Environment, meta
>>> env = Environment()
>>> ast = env.parse('{% set foo = 42 %}{{ bar + foo }}')
>>> meta.find_undeclared_variables(ast) == {'bar'}
True

.. admonition:: Implementation

   Internally the code generator is used for finding undeclared variables.
   This is good to know because the code generator might raise a
   :exc:`TemplateAssertionError` during compilation and as a matter of
   fact this function can currently raise that exception as well.