Turn the relative date in question to absolute date (#3372)

### What problem does this PR solve?


### Type of change

- [x] Performance Improvement

api/db/services/dialog_service.py

 import re
 from copy import deepcopy
 from timeit import default_timer as timer
-
-
+import datetime
+from datetime import timedelta
 from api.db import LLMType, ParserType,StatusEnum
 from api.db.db_models import Dialog, Conversation,DB
 from api.db.services.common_service import CommonService
         if m["role"] not in ["user", "assistant"]: continue
         conv.append("{}: {}".format(m["role"].upper(), m["content"]))
     conv = "\n".join(conv)
+    today = datetime.date.today().isoformat()
+    yesterday = (datetime.date.today() - timedelta(days=1)).isoformat()
+    tomorrow = (datetime.date.today() + timedelta(days=1)).isoformat()
     prompt = f"""
 Role: A helpful assistant
-Task: Generate a full user question that would follow the conversation.
+
+Task and steps: 
+    1. Generate a full user question that would follow the conversation.
+    2. If the user's question involves relative date, you need to convert it into absolute date based on the current date, which is {today}. For example: 'yesterday' would be converted to {yesterday}.
+    
 Requirements & Restrictions:
   - Text generated MUST be in the same language of the original user's question.
   - If the user's latest question is completely, don't do anything, just return the original question.
 ###############
 Output: What's the full name of Donald Trump's mother Mary Trump?
 
+------------
+# Example 3
+## Conversation
+USER: What's the weather today in London?
+ASSISTANT:  Cloudy.
+USER: What's about tomorrow in Rochester?
+###############
+Output: What's the weather in Rochester on {tomorrow}?
 ######################
 
 # Real Data