👌 From string fix (#1031)

docs/changelog.rst

@@ -23,6 +23,7 @@ Released: under development
 * Improvement: Suffix all warnings with ``[needs]``, and allow them to be suppressed
   (`#975 <https://github.com/useblocks/sphinx-needs/pull/975>`_)
 * Improvement: :ref:`needextend` for single needs is much faster.
+* Improvement: external_needs is using cached templates to save generation time.
 
 1.3.0
 -----

sphinx_needs/external_needs.py

@@ -1,8 +1,9 @@
 import json
 import os
+from functools import lru_cache
 
 import requests
-from jinja2 import Environment
+from jinja2 import Environment, Template
 from requests_file import FileAdapter
 from sphinx.application import Sphinx
 from sphinx.environment import BuildEnvironment
@@ -17,6 +18,16 @@
 log = get_logger(__name__)
 
 
+@lru_cache(maxsize=20)
+def get_target_template(target_url: str) -> Template:
+    """
+    Provides template for target_link style
+    Can be cached, as the template is always the same for a given target_url
+    """
+    mem_template = Environment().from_string(target_url)
+    return mem_template
+
+
 def load_external_needs(app: Sphinx, env: BuildEnvironment, _docname: str) -> None:
     needs_config = NeedsSphinxConfig(app.config)
     for source in needs_config.external_needs:
@@ -95,7 +106,7 @@ def load_external_needs(app: Sphinx, env: BuildEnvironment, _docname: str) -> No
 
             if target_url:
                 # render jinja content
-                mem_template = Environment().from_string(target_url)
+                mem_template = get_target_template(target_url)
                 cal_target_url = mem_template.render(**{"need": need})
                 need_params["external_url"] = f'{source["base_url"]}/{cal_target_url}'
             else: