[REF-2157] Allow `rx.download` to resolve `rx.get_upload_url` links (#2813)

reflex/.templates/web/utils/state.js

@@ -161,7 +161,8 @@ export const applyEvent = async (event, socket) => {
   if (event.name == "_download") {
     const a = document.createElement("a");
     a.hidden = true;
-    a.href = event.payload.url;
+    // Special case when linking to uploaded files
+    a.href = event.payload.url.replace("${getBackendURL(env.UPLOAD)}", getBackendURL(env.UPLOAD))
     a.download = event.payload.filename;
     a.click();
     a.remove();

reflex/components/core/upload.py

@@ -128,7 +128,7 @@ uploaded_files_url_prefix: Var = Var.create_safe(
 )
 
 
-def get_upload_url(file_path: str) -> str:
+def get_upload_url(file_path: str) -> Var[str]:
     """Get the URL of an uploaded file.
 
     Args:
@@ -139,7 +139,7 @@ def get_upload_url(file_path: str) -> str:
     """
     Upload.is_used = True
 
-    return f"{uploaded_files_url_prefix}/{file_path}"
+    return Var.create_safe(f"{uploaded_files_url_prefix}/{file_path}")
 
 
 def _on_drop_spec(files: Var):

reflex/components/core/upload.pyi

@@ -40,7 +40,7 @@ def get_upload_dir() -> Path: ...
 
 uploaded_files_url_prefix: Var
 
-def get_upload_url(file_path: str) -> str: ...
+def get_upload_url(file_path: str) -> Var[str]: ...
 
 class UploadFilesProvider(Component):
     @overload