Schema for a StructuredOutputParser in langchain

chain_schema.py

# See previous gist https://gist.github.com/iht/d5bedff9ee86ed5223cfa2ad06080ca0
import json 
# ...
from langchain.output_parsers import ResponseSchema, StructuredOutputParser

def _dict_to_json(x: dict) -> str:
  return "```\n" + json.dumps(x) + "\n```"

response_schema = [
    ResponseSchema(name="query", description="SQL query to solve the user question."),
    ResponseSchema(name="question", description="Question asked by the user."),
    ResponseSchema(name="context", description="Documents retrieved from the vector store.")]
    
output_parser = StructuredOutputParser.from_response_schemas(response_schema)

# ... 

chain1 = question | docs | some_prompt | some_model1 | StrOutputParser()
json_chain1 = {"output": chain1} | question | docs | RunnableLambda(_dict_to_json) | StrOutputParser()
output_chain1 = json_chain1 | output_parser