chore: lazily import some external dependencies

These contribute considerably to startup time and are not always needed.

weblate/formats/convert.py

@@ -18,14 +18,12 @@
 from django.utils.translation import gettext_lazy
 from translate.convert.po2html import po2html
 from translate.convert.po2idml import translate_idml, write_idml
-from translate.convert.po2md import MarkdownTranslator
 from translate.convert.po2rc import rerc
 from translate.convert.po2txt import po2txt
 from translate.convert.rc2po import rc2po
 from translate.convert.xliff2odf import translate_odf, write_odf
 from translate.storage.html import htmlfile
 from translate.storage.idml import INLINE_ELEMENTS, NO_TRANSLATE_ELEMENTS, open_idml
-from translate.storage.markdown import MarkdownFile
 from translate.storage.odf_io import open_odf
 from translate.storage.odf_shared import inline_elements, no_translate_content_elements
 from translate.storage.po import pofile
@@ -315,12 +313,18 @@ class MarkdownFormat(ConvertFormat):
     check_flags = ("safe-html", "strict-same", "md-text")
 
     def convertfile(self, storefile, template_store):
+        # Lazy import as mistletoe is expensive
+        from translate.storage.markdown import MarkdownFile
+
         # Fake input file with a blank filename
         mdparser = MarkdownFile(inputfile=NamedBytesIO("", storefile.read()))
         return self.convert_to_po(mdparser, template_store, use_location=False)
 
     def save_content(self, handle) -> None:
         """Store content to file."""
+        # Lazy import as mistletoe is expensive
+        from translate.convert.po2md import MarkdownTranslator
+
         converter = MarkdownTranslator(
             inputstore=self.store, includefuzzy=True, outputthreshold=None, maxlength=80
         )

weblate/memory/models.py

@@ -15,8 +15,6 @@
 from django.db.models.functions import MD5
 from django.utils.encoding import force_str
 from django.utils.translation import gettext, pgettext
-from jsonschema import validate
-from jsonschema.exceptions import ValidationError
 from translate.misc.xml_helpers import getXMLlang, getXMLspace
 from translate.storage.tmx import tmxfile
 from weblate_schemas import load_schema
@@ -170,6 +168,10 @@ def import_file(
     def import_json(
         self, request: AuthenticatedHttpRequest, fileobj, origin=None, **kwargs
     ):
+        # Lazily import as this is expensive
+        from jsonschema import validate
+        from jsonschema.exceptions import ValidationError
+
         content = fileobj.read()
         try:
             data = json.loads(force_str(content))

weblate/utils/request.py

@@ -5,8 +5,6 @@
 
 from typing import TYPE_CHECKING
 
-import user_agents
-
 if TYPE_CHECKING:
     from weblate.auth.models import AuthenticatedHttpRequest
 
@@ -30,6 +28,9 @@ def get_user_agent_raw(request: AuthenticatedHttpRequest) -> str:
 
 def get_user_agent(request: AuthenticatedHttpRequest, max_length: int = 200) -> str:
     """Return formatted user agent for request."""
+    # Lazily import as this is expensive
+    import user_agents
+
     raw = get_user_agent_raw(request)
     if not raw:
         return ""