diff --git a/api/controllers/console/datasets/rag_pipeline/datasource_content_preview.py b/api/controllers/console/datasets/rag_pipeline/datasource_content_preview.py
index 856e4a1c70..d413def27f 100644
--- a/api/controllers/console/datasets/rag_pipeline/datasource_content_preview.py
+++ b/api/controllers/console/datasets/rag_pipeline/datasource_content_preview.py
@@ -4,7 +4,7 @@ from flask_restx import (  # type: ignore
 )
 from werkzeug.exceptions import Forbidden
 
-from controllers.console import console_ns
+from controllers.console import api, console_ns
 from controllers.console.datasets.wraps import get_rag_pipeline
 from controllers.console.wraps import account_initialization_required, setup_required
 from libs.login import current_user, login_required
@@ -12,9 +12,17 @@ from models import Account
 from models.dataset import Pipeline
 from services.rag_pipeline.rag_pipeline import RagPipelineService
 
+parser = (
+    reqparse.RequestParser()
+    .add_argument("inputs", type=dict, required=True, nullable=False, location="json")
+    .add_argument("datasource_type", type=str, required=True, location="json")
+    .add_argument("credential_id", type=str, required=False, location="json")
+)
+
 
 @console_ns.route("/rag/pipelines/<uuid:pipeline_id>/workflows/published/datasource/nodes/<string:node_id>/preview")
 class DataSourceContentPreviewApi(Resource):
+    @api.expect(parser)
     @setup_required
     @login_required
     @account_initialization_required
@@ -26,12 +34,6 @@ class DataSourceContentPreviewApi(Resource):
         if not isinstance(current_user, Account):
             raise Forbidden()
 
-        parser = (
-            reqparse.RequestParser()
-            .add_argument("inputs", type=dict, required=True, nullable=False, location="json")
-            .add_argument("datasource_type", type=str, required=True, location="json")
-            .add_argument("credential_id", type=str, required=False, location="json")
-        )
         args = parser.parse_args()
 
         inputs = args.get("inputs")