refactor: replace hardcoded user plan strings with CloudPlan enum (#27675)

api/tasks/document_indexing_task.py

@@ -6,6 +6,7 @@ from celery import shared_task
 
 from configs import dify_config
 from core.indexing_runner import DocumentIsPausedError, IndexingRunner
+from enums.cloud_plan import CloudPlan
 from extensions.ext_database import db
 from libs.datetime_utils import naive_utc_now
 from models.dataset import Dataset, Document
@@ -38,7 +39,7 @@ def document_indexing_task(dataset_id: str, document_ids: list):
             vector_space = features.vector_space
             count = len(document_ids)
             batch_upload_limit = int(dify_config.BATCH_UPLOAD_LIMIT)
-            if features.billing.subscription.plan == "sandbox" and count > 1:
+            if features.billing.subscription.plan == CloudPlan.SANDBOX and count > 1:
                 raise ValueError("Your current plan does not support batch upload, please upgrade your plan.")
             if count > batch_upload_limit:
                 raise ValueError(f"You have reached the batch upload limit of {batch_upload_limit}.")