fix: lazy load exchange excel codecs

iti/exchange/routes.py

@@ -27,7 +27,6 @@ from .schemas import (
     ExchangeTemplateUpdateRequest,
 )
 from .service import ExchangeService
-from .excel import ExcelTemplateCodec
 from .sources import get_exchange_source
 
 
@@ -383,7 +382,7 @@ def upload_template_version(
 ):
     service = ExchangeService(request.app, db)
     content = file.file.read()
-    parsed = ExcelTemplateCodec().load(content)
+    parsed = _excel_template_codec().load(content)
     snapshot = service.publish_version(
         template_id=template_id,
         version=version,
@@ -404,6 +403,12 @@ def upload_template_version(
     return ok(ExchangeTemplateVersionResponse.model_validate(_version_payload(snapshot)).model_dump(mode="json"))
 
 
+def _excel_template_codec():
+    from .excel import ExcelTemplateCodec
+
+    return ExcelTemplateCodec()
+
+
 @router.post("/tasks")
 def create_task(
     payload: ExchangeTaskCreateRequest,

iti/exchange/service.py

@@ -21,7 +21,6 @@ from .base import (
     ExchangeTemplateSnapshot,
     ExchangeTaskKind,
 )
-from .excel import ExcelTemplateCodec, ExcelWorkbookCodec
 from .models import (
     ExchangeTaskModel,
     ExchangeTaskRowModel,
@@ -136,7 +135,7 @@ class ExchangeService:
             with storage.download(version.file_key) as file_stream:
                 return file_stream.read()
         snapshot = self.snapshot_from_model(version)
-        return ExcelTemplateCodec().dump(snapshot)
+        return _excel_template_codec().dump(snapshot)
 
     def build_plan_template_file(self, plan: ExchangePlan) -> bytes:
         if plan.version_id:
@@ -145,7 +144,7 @@ class ExchangeService:
                 storage = get_exchange_storage(self.app)
                 with storage.download(version.file_key) as file_stream:
                     return file_stream.read()
-        return ExcelTemplateCodec().dump(plan)
+        return _excel_template_codec().dump(plan)
 
     def export_rows(
         self,
@@ -155,7 +154,7 @@ class ExchangeService:
         fields: list[ExchangeField] | None = None,
         sheet_name: str | None = None,
     ) -> bytes:
-        workbook_codec = ExcelWorkbookCodec()
+        workbook_codec = _excel_workbook_codec()
         if plan is not None:
             return workbook_codec.export_rows_with_plan(
                 plan=plan,
@@ -180,7 +179,7 @@ class ExchangeService:
         plan: ExchangePlan | None = None,
         fields: list[ExchangeField] | None = None,
     ) -> list[dict[str, Any]]:
-        workbook_codec = ExcelWorkbookCodec()
+        workbook_codec = _excel_workbook_codec()
         if plan is not None and plan.fields:
             return workbook_codec.import_rows_with_fields(content, fields=list(plan.fields))
         if fields is not None:
@@ -501,6 +500,18 @@ def _excel_mime_type() -> str:
     return "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
 
 
+def _excel_template_codec():
+    from .excel import ExcelTemplateCodec
+
+    return ExcelTemplateCodec()
+
+
+def _excel_workbook_codec():
+    from .excel import ExcelWorkbookCodec
+
+    return ExcelWorkbookCodec()
+
+
 def _jsonable(value: Any) -> Any:
     if isinstance(value, Enum):
         return value.value

iti/exchange/sources.py

@@ -14,7 +14,6 @@ from .base import (
     ExchangeTemplateSource,
     ExchangeTemplateSourceKind,
 )
-from .excel import ExcelTemplateCodec
 
 
 class ExchangeSource(Protocol):
@@ -75,7 +74,7 @@ class MappingExchangeSource:
         )
 
     def load_template_file(self, plan: ExchangePlan) -> bytes | None:
-        return ExcelTemplateCodec().dump(plan)
+        return _excel_template_codec().dump(plan)
 
 
 @dataclass
@@ -131,7 +130,7 @@ class LocalExchangeSource:
             from .service import ExchangeService
 
             return ExchangeService(self.app, self.db).build_template_file(plan.version_id)
-        return ExcelTemplateCodec().dump(plan)
+        return _excel_template_codec().dump(plan)
 
 
 @dataclass
@@ -192,7 +191,7 @@ class RemoteExchangeSource:
 
     def load_template_file(self, plan: ExchangePlan) -> bytes | None:
         if not plan.version_id:
-            return ExcelTemplateCodec().dump(plan)
+            return _excel_template_codec().dump(plan)
         client = service_client(self.app, self.service_name)
         response = client.get(
             f"/exchange/template-versions/{plan.version_id}/download",
@@ -259,6 +258,12 @@ def _placeholder_from_mapping(item: dict[str, Any]) -> ExchangePlaceholder:
     )
 
 
+def _excel_template_codec():
+    from .excel import ExcelTemplateCodec
+
+    return ExcelTemplateCodec()
+
+
 def get_exchange_source(
     app: Any,
     *,