Fix: remove KB id restriction while creating chat. (#5588)

### What problem does this PR solve?

#5586

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/apps/sdk/chat.py

@@ -31,9 +31,7 @@ from api.utils.api_utils import get_result
 @token_required
 def create(tenant_id):
     req = request.json
-    ids = req.get("dataset_ids")
-    if not ids:
-        return get_error_data_result(message="`dataset_ids` is required")
+    ids = [i for i in req.get("dataset_ids", []) if i]
     for kb_id in ids:
         kbs = KnowledgebaseService.accessible(kb_id=kb_id, user_id=tenant_id)
         if not kbs:
@@ -42,10 +40,10 @@ def create(tenant_id):
         kb = kbs[0]
         if kb.chunk_num == 0:
             return get_error_data_result(f"The dataset {kb_id} doesn't own parsed file")
-    kbs = KnowledgebaseService.get_by_ids(ids)
+    kbs = KnowledgebaseService.get_by_ids(ids) if ids else []
     embd_ids = [TenantLLMService.split_model_name_and_factory(kb.embd_id)[0] for kb in kbs]  # remove vendor suffix for comparison
     embd_count = list(set(embd_ids))
-    if len(embd_count) != 1:
+    if len(embd_count) > 1:
         return get_result(message='Datasets use different embedding models."',
                           code=settings.RetCode.AUTHENTICATION_ERROR)
     req["kb_ids"] = ids