refactor(trigger): streamline OAuth client existence check

Replaced the method for checking the existence of a system OAuth client with a new dedicated method `is_oauth_system_client_exists` in the TriggerProviderService. This improves code clarity and encapsulates the logic for verifying the presence of a system-level OAuth client. Updated the TriggerOAuthClientManageApi to utilize the new method for better readability.

api/controllers/console/workspace/trigger_providers.py

@@ -469,9 +469,7 @@ class TriggerOAuthClientManageApi(Resource):
                 tenant_id=user.current_tenant_id,
                 provider_id=provider_id,
             )
-
-            # Check if there's a system OAuth client
-            system_client = TriggerProviderService.get_oauth_client(
+            system_client_exists = TriggerProviderService.is_oauth_system_client_exists(
                 tenant_id=user.current_tenant_id,
                 provider_id=provider_id,
             )
@@ -479,8 +477,8 @@ class TriggerOAuthClientManageApi(Resource):
             redirect_uri = f"{dify_config.CONSOLE_API_URL}/console/api/oauth/plugin/{provider}/trigger/callback"
             return jsonable_encoder(
                 {
-                    "configured": bool(custom_params or system_client),
-                    "system_configured": bool(system_client),
+                    "configured": bool(custom_params or system_client_exists),
+                    "system_configured": system_client_exists,
                     "custom_configured": bool(custom_params),
                     "oauth_client_schema": provider_controller.get_oauth_client_schema(),
                     "custom_enabled": is_custom_enabled,

api/services/trigger/trigger_provider_service.py

@@ -471,7 +471,7 @@ class TriggerProviderService:
 
             is_verified = PluginService.is_plugin_verified(tenant_id, provider_id.plugin_id)
             if not is_verified:
-                return oauth_params
+                return None
 
             # Check for system-level OAuth client
             system_client: TriggerOAuthSystemClient | None = (
@@ -488,6 +488,22 @@ class TriggerProviderService:
 
             return oauth_params
 
+    @classmethod
+    def is_oauth_system_client_exists(cls, tenant_id: str, provider_id: TriggerProviderID) -> bool:
+        """
+        Check if system OAuth client exists for a trigger provider.
+        """
+        is_verified = PluginService.is_plugin_verified(tenant_id, provider_id.plugin_id)
+        if not is_verified:
+            return False
+        with Session(db.engine, expire_on_commit=False) as session:
+            system_client: TriggerOAuthSystemClient | None = (
+                session.query(TriggerOAuthSystemClient)
+                .filter_by(plugin_id=provider_id.plugin_id, provider=provider_id.provider_name)
+                .first()
+            )
+            return system_client is not None
+
     @classmethod
     def save_custom_oauth_client_params(
         cls,