LangChain-02 JsonOutputParser 原创
安装依赖
pip install --upgrade --quiet langchain-core langchain-community langchain-openai
我在环境变量中配置了,所以后续在代码中可以省略这个参数。
export OPENAI_API_KEY="sk-UkyBxxxx"
export OPENAI_API_BASE="https://wzk....."
编写代码
from langchain_core.output_parsers import JsonOutputParser
from langchain_openai.chat_models import ChatOpenAI
async def main():
model = ChatOpenAI(
model="gpt-3.5-turbo",
)
chain = (
model | JsonOutputParser()
) # Due to a bug in older versions of Langchain, JsonOutputParser did not stream results from some models
async for text in chain.astream(
'output a list of the countries france, spain and japan and their populations in JSON format. Use a dict with an outer key of "countries" which contains a list of countries. Each country should have the key `name` and `population`'
):
print(text, flush=True)
if __name__ == '__main__':
import asyncio
asyncio.run(main())
执行代码
➜ python3 test04.py
{}
{'countries': []}
{'countries': [{}]}
{'countries': [{'name': ''}]}
{'countries': [{'name': 'France'}]}
{'countries': [{'name': 'France', 'population': 670}]}
{'countries': [{'name': 'France', 'population': 670760}]}
{'countries': [{'name': 'France', 'population': 67076000}]}
{'countries': [{'name': 'France', 'population': 67076000}, {}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': ''}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain'}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 467}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 467330}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 46733038}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 46733038}, {}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 46733038}, {'name': ''}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 46733038}, {'name': 'Japan'}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 46733038}, {'name': 'Japan', 'population': 126}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 46733038}, {'name': 'Japan', 'population': 126476}]}
{'countries': [{'name': 'France', 'population': 67076000}, {'name': 'Spain', 'population': 46733038}, {'name': 'Japan', 'population': 126476458}]}
提取JSON
定义一个函数
def _extract_country_names(inputs):
"""A function that does not operates on input streams and breaks streaming."""
if not isinstance(inputs, dict):
return ""
if "countries" not in inputs:
return ""
countries = inputs["countries"]
if not isinstance(countries, list):
return ""
country_names = [
country.get("name") for country in countries if isinstance(country, dict)
]
return country_names
通过 Chain
将函数链接起来
# 上文写的是:model | JsonOutputParser(),这里修改为:
chain = model | JsonOutputParser() | _extract_country_names
再次执行
➜ python3 test04.py
[None, '', 'France', 'France', 'France', 'France', 'France', None, 'France', '', 'France', 'Spain', 'France', 'Spain', 'France', 'Spain', 'France', 'Spain', 'France', 'Spain', None, 'France', 'Spain', '', 'France', 'Spain', 'Japan', 'France', 'Spain', 'Japan', 'France', 'Spain', 'Japan', 'France', 'Spain', 'Japan']
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