OutputParser

🔹 2. OutputParser

| 功能 | 让 LLM 输出符合你定义的结构（如 JSON、数值、列表等） |
| 常见类型 | StructuredOutputParser, PydanticOutputParser, RegexParser, CommaSeparatedListOutputParser |

示例（使用 JSON 格式）：

python
复制编辑
from langchain.output_parsers import StructuredOutputParser
from langchain.output_parsers.format_instructions import get_format_instructions

parser = StructuredOutputParser.from_names_and_descriptions({
    "name": "The person's name",
    "age": "The person's age"
})

format_instructions = parser.get_format_instructions()

prompt = PromptTemplate(
    template="Extract name and age:\n\n{text}\n\n{format_instructions}",
    input_variables=["text"],
    partial_variables={"format_instructions": format_instructions}
)