ashb commented on a change in pull request #5461: [AIRFLOW-4835] Refactor
render_template
URL: https://github.com/apache/airflow/pull/5461#discussion_r309624776
##########
File path: airflow/models/baseoperator.py
##########
@@ -636,51 +636,71 @@ def __setstate__(self, state):
self.__dict__ = state
self._log = logging.getLogger("airflow.task.operators")
- def render_template_from_field(self, attr, content, context, jinja_env):
+ def render_template_fields(self, context: Dict) -> None:
"""
- Renders a template from a field. If the field is a string, it will
- simply render the string and return the result. If it is a collection
or
- nested set of collections, it will traverse the structure and render
- all elements in it. If the field has another type, it will return it
as it is.
+ Template all attributes listed in template_fields. Note this operation
is irreversible.
+
+ :param context: Dict with values to apply on content
+ :type context: dict
+ """
+ if self.template_fields:
+ if self.dag.user_defined_macros:
+ context.update(self.dag.user_defined_macros)
+
+ for attr_name in self.template_fields:
+ content = getattr(self, attr_name)
+ if content:
+ rendered_content = self.render_template(content, context)
+ setattr(self, attr_name, rendered_content)
+
+ def render_template(
+ self, content: Any, context: Dict, jinja_env:
Optional[jinja2.Environment] = None
+ ) -> Any:
"""
- rt = self.render_template
+ Render a templated string. The content can be a collection holding
multiple templated strings and will
+ be templated recursively.
+
+ :param content: Content to template. Only strings can be templated
(may be inside collection).
+ :type content: Any
+ :param context: Dict with values to apply on templated content
+ :type context: dict
+ :param jinja_env: Jinja environment. Can be provided to avoid
re-creating Jinja environments during
+ recursion.
+ :type jinja_env: jinja2.Environment
+ :return: Templated content
+ """
+
+ if not jinja_env:
+ jinja_env = self.get_template_env()
+
if isinstance(content, str):
- result = jinja_env.from_string(content).render(**context)
- elif isinstance(content, tuple):
+ if any([content.endswith(ext) for ext in self.template_ext]):
+ # Content contains a filepath
+ return jinja_env.get_template(content).render(**context)
+ else:
+ return jinja_env.from_string(content).render(**context)
+
+ if isinstance(content, tuple):
if type(content) is not tuple:
# Special case for named tuples
- result = content.__class__(*(rt(attr, e, context) for e in
content))
+ return content.__class__(
+ *(self.render_template(element, context, jinja_env) for
element in content)
+ )
else:
- result = tuple(rt(attr, e, context) for e in content)
+ return tuple(self.render_template(element, context, jinja_env)
for element in content)
+
elif isinstance(content, list):
- result = [rt(attr, e, context) for e in content]
- elif isinstance(content, dict):
- result = {
- k: rt("{}[{}]".format(attr, k), v, context)
- for k, v in list(content.items())}
- else:
- result = content
- return result
+ return [self.render_template(element, context, jinja_env) for
element in content]
- def render_template(self, attr, content, context):
- """
- Renders a template either from a file or directly in a field, and
returns
- the rendered result.
- """
- jinja_env = self.get_template_env()
+ elif isinstance(content, dict):
+ return {key: self.render_template(value, context, jinja_env) for
key, value in content.items()}
- exts = self.__class__.template_ext
- if (
- isinstance(content, str) and
- any([content.endswith(ext) for ext in exts])):
- return jinja_env.get_template(content).render(**context)
else:
- return self.render_template_from_field(attr, content, context,
jinja_env)
+ return content
- def get_template_env(self):
- return self.dag.get_template_env() \
- if hasattr(self, 'dag') \
- else jinja2.Environment(cache_size=0)
+ def get_template_env(self) -> jinja2.Environment:
+ """Fetch a Jinja template environment from the DAG or instantiate
empty environment if no DAG."""
+ return self.dag.get_template_env() if hasattr(self, 'dag') else
jinja2.Environment(cache_size=0)
Review comment:
```suggestion
return self.dag.get_template_env() if self.has_dag() else
jinja2.Environment(cache_size=0)
```
Especially given the attribute is `_dag` :)
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