engine/backup.py: remove conditional code related to target_dir (cvat-ai#9998)

In `TaskExporter`, it is trivially obviated by using "" as the default
directory. In `ProjectExporter`, target directories are not supported at
all, so remove such parameters completely.

Also, add/improve type annotations for all affected methods.

Author: SpecLad

cvat/apps/engine/backup.py

@@ -91,13 +91,17 @@ def _get_label_mapping(db_labels):
 
 
 def _write_annotation_guide(
-    zip_object, annotation_guide, guide_filename, assets_dirname, target_dir=None
-):
+    zip_object: ZipFile,
+    annotation_guide: Optional[models.AnnotationGuide],
+    guide_filename: str,
+    assets_dirname: str,
+    target_dir: str,
+) -> None:
     if annotation_guide is not None:
         md = annotation_guide.markdown
         assets = annotation_guide.assets.all()
-        assets_dirname = os.path.join(target_dir or "", assets_dirname)
-        guide_filename = os.path.join(target_dir or "", guide_filename)
+        assets_dirname = os.path.join(target_dir, assets_dirname)
+        guide_filename = os.path.join(target_dir, guide_filename)
 
         for db_asset in assets:
             md = md.replace(
@@ -386,7 +390,7 @@ def _write_directory(
                 )
 
     @abstractmethod
-    def export_to(self, file: str | ZipFile, target_dir: str | None = None): ...
+    def export_to(self, file: str) -> None: ...
 
     @classmethod
     def get_object(cls, pk: int) -> models.Project | models.Task:
@@ -420,7 +424,7 @@ def __init__(self, pk, version=Version.V1, *, lightweight: bool):
         self._label_mapping = _get_label_mapping(db_labels)
         self._lightweight = lightweight
 
-    def _write_annotation_guide(self, zip_object, target_dir=None):
+    def _write_annotation_guide(self, zip_object: ZipFile, target_dir: str) -> None:
         annotation_guide = (
             self._db_task.annotation_guide if hasattr(self._db_task, "annotation_guide") else None
         )
@@ -432,10 +436,9 @@ def _write_annotation_guide(self, zip_object, target_dir=None):
             target_dir=target_dir,
         )
 
-    def _write_data(self, zip_object, target_dir=None):
-        target_data_dir = (
-            os.path.join(target_dir, self.DATA_DIRNAME) if target_dir else self.DATA_DIRNAME
-        )
+    def _write_data(self, zip_object: ZipFile, target_dir: str) -> None:
+        target_data_dir = os.path.join(target_dir, self.DATA_DIRNAME)
+
         if self._db_data.storage == StorageChoice.LOCAL:
             data_dir = self._db_data.get_upload_dirname()
             self._write_directory(
@@ -547,19 +550,18 @@ def _write_data(self, zip_object, target_dir=None):
         else:
             raise NotImplementedError
 
-    def _write_task(self, zip_object, target_dir=None):
+    def _write_task(self, zip_object: ZipFile, target_dir: str) -> None:
         task_dir = self._db_task.get_dirname()
-        target_task_dir = (
-            os.path.join(target_dir, self.TASK_DIRNAME) if target_dir else self.TASK_DIRNAME
-        )
+        target_task_dir = os.path.join(target_dir, self.TASK_DIRNAME)
+
         self._write_directory(
             source_dir=task_dir,
             zip_object=zip_object,
             target_dir=target_task_dir,
             recursive=False,
         )
 
-    def _write_manifest(self, zip_object, target_dir=None):
+    def _write_manifest(self, zip_object: ZipFile, target_dir: str) -> None:
         def serialize_task():
             task_serializer = TaskReadSerializer(self._db_task)
             for field in ("url", "owner", "assignee"):
@@ -674,14 +676,10 @@ def serialize_data():
         task["data"] = serialize_data()
         task["jobs"] = serialize_jobs()
 
-        target_manifest_file = (
-            os.path.join(target_dir, self.MANIFEST_FILENAME)
-            if target_dir
-            else self.MANIFEST_FILENAME
-        )
+        target_manifest_file = os.path.join(target_dir, self.MANIFEST_FILENAME)
         zip_object.writestr(target_manifest_file, data=JSONRenderer().render(task))
 
-    def _write_annotations(self, zip_object: ZipFile, target_dir: Optional[str] = None) -> None:
+    def _write_annotations(self, zip_object: ZipFile, target_dir: str) -> None:
         def serialize_annotations():
             db_jobs = self._get_db_jobs()
             db_job_ids = (j.id for j in db_jobs)
@@ -708,22 +706,18 @@ def serialize_shapes():
                     yield self._prepare_annotations(annotation_data, self._label_mapping)
 
         annotations = serialize_annotations()
-        target_annotations_file = (
-            os.path.join(target_dir, self.ANNOTATIONS_FILENAME)
-            if target_dir
-            else self.ANNOTATIONS_FILENAME
-        )
+        target_annotations_file = os.path.join(target_dir, self.ANNOTATIONS_FILENAME)
         with zip_object.open(target_annotations_file, "w") as f:
             rapidjson.dump(annotations, f)
 
-    def _export_task(self, zip_obj, target_dir=None):
+    def _export_task(self, zip_obj: ZipFile, target_dir: str) -> None:
         self._write_data(zip_obj, target_dir)
         self._write_task(zip_obj, target_dir)
         self._write_manifest(zip_obj, target_dir)
         self._write_annotations(zip_obj, target_dir)
         self._write_annotation_guide(zip_obj, target_dir)
 
-    def export_to(self, file: str | ZipFile, target_dir: str | None = None):
+    def export_to(self, file: str | ZipFile, target_dir: str = "") -> None:
         if (
             self._db_task.data.storage_method == StorageMethodChoice.FILE_SYSTEM
             and self._db_task.data.storage == StorageChoice.SHARE
@@ -1154,7 +1148,7 @@ def __init__(self, pk, *, lightweight: bool, version: Version = Version.V1):
         self._label_mapping = _get_label_mapping(db_labels)
         self._lightweight = lightweight
 
-    def _write_annotation_guide(self, zip_object, target_dir=None):
+    def _write_annotation_guide(self, zip_object: ZipFile) -> None:
         annotation_guide = (
             self._db_project.annotation_guide
             if hasattr(self._db_project, "annotation_guide")
@@ -1165,7 +1159,7 @@ def _write_annotation_guide(self, zip_object, target_dir=None):
             annotation_guide,
             self.ANNOTATION_GUIDE_FILENAME,
             self.ASSETS_DIRNAME,
-            target_dir=target_dir,
+            target_dir="",
         )
 
     def _write_tasks(self, zip_object):
@@ -1201,7 +1195,7 @@ def serialize_project():
 
         zip_object.writestr(self.MANIFEST_FILENAME, data=JSONRenderer().render(project))
 
-    def export_to(self, file: str, target_dir: str | None = None):
+    def export_to(self, file: str) -> None:
         with ZipFile(file, "w") as output_file:
             self._write_annotation_guide(output_file)
             self._write_manifest(output_file)