feat: 从 FastAPI 导出 openapi.json 并渲染为 API 文档

通过 vitepress-openapi 插件,在 VitePress 文档中实现基于 openapi.json 的 API 文档。
这样实现的 API 文档可以从最新版本的代码库中提取路由信息,继而实现自动集成。
---
同时,通过 Kimi 和 Deepseek 实现并审查了一个对 Google 风格 docstring 的解析函数。
该函数可以从 Google 风格的 docstring 中提取参数文档并按 openapi 规范重新整理它们。
---
增加了 nyahome openapi 命令用来导出 openapi.json。
增加了 task openapi-docs 命令用来准备未来的持续集成。
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2026-05-25 14:56:36 +08:00
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"""
FastAPI Docstring-to-OpenAPI Enricher
=====================================
自动解析 Google Style docstring,将 Args / Returns / Raises 注入到 OpenAPI Schema 的对应位置,
让 vitepress-openapi 等工具能够正确渲染参数表格和返回值说明。
功能特性
--------
1. 参数描述注入:路径参数、查询参数、Header、Cookie、请求体字段
2. 返回值描述注入:自动写入 2xx 响应的 description 及 schema.description
3. 异常描述注入:以 Markdown 格式附加到 operation description
4. 嵌套 Schema 递归处理:支持 Pydantic v1/v2 的嵌套模型、List、Optional 等
5. \f 截断兼容:与 FastAPI 原生行为保持一致
6. 全局 Schema 补全:为 components/schemas 中缺少描述的字段补充 docstring 说明
7. 零侵入:只需替换 ``app.openapi``,业务代码无需任何修改
依赖安装
--------
pip install docstring-parser
使用方式
--------
from fastapi import FastAPI
from fastapi_docstring_openapi import enrich_openapi_from_docstrings
app = FastAPI()
enrich_openapi_from_docstrings(app)
# 你的路由注册...
完整示例见文件底部 ``if __name__ == "__main__":`` 块。
"""
from __future__ import annotations
import inspect
import logging
from typing import Any, Dict, Optional, Set
from docstring_parser import DocstringStyle, ParseError, parse
from fastapi import FastAPI
from fastapi.openapi.utils import get_openapi
logger = logging.getLogger(__name__)
def _parse_docstring(
func: Any, style: DocstringStyle = DocstringStyle.AUTO
) -> Optional[Any]:
"""解析函数的 Google Style docstring,失败时返回 None。"""
doc = inspect.getdoc(func)
if not doc:
return None
if "\f" in doc:
doc = doc.split("\f")[0].strip()
try:
return parse(doc, style=style)
except ParseError:
return None
except Exception:
logger.warning(
"Unexpected error parsing docstring for %s",
getattr(func, "__name__", func),
exc_info=True,
)
return None
def _build_param_lookup(parsed_doc: Any) -> Dict[str, str]:
"""从解析后的 docstring 构建 {参数名: 描述} 映射。"""
lookup: Dict[str, str] = {}
for param in getattr(parsed_doc, "params", []) or []:
name = getattr(param, "arg_name", None)
desc = getattr(param, "description", None) or ""
if name:
# 合并多行描述并清理缩进
lookup[name] = _dedent_description(desc)
return lookup
def _build_returns_description(parsed_doc: Any) -> Optional[str]:
"""从解析后的 docstring 构建返回值描述。"""
ret = getattr(parsed_doc, "returns", None)
if not ret:
return None
type_name = getattr(ret, "type_name", None) or ""
desc = getattr(ret, "description", None) or ""
if type_name and desc:
return f"**{type_name}**: {desc}"
return desc or None
def _build_raises_description(parsed_doc: Any) -> Optional[str]:
"""从解析后的 docstring 构建异常描述(Markdown 列表)。"""
raises = getattr(parsed_doc, "raises", None)
if not raises:
return None
parts: list[str] = []
for exc in raises:
type_name = getattr(exc, "type_name", None) or ""
desc = getattr(exc, "description", None) or ""
if type_name and desc:
parts.append(f"- **{type_name}**: {desc}")
elif type_name:
parts.append(f"- **{type_name}**")
elif desc:
parts.append(f"- {desc}")
return "\n".join(parts) if parts else None
def _dedent_description(text: str) -> str:
"""清理 docstring 描述中的多余缩进,保留段落结构。"""
if not text:
return ""
lines = text.splitlines()
# 找到最小公共缩进(排除空行)
min_indent = min(
(len(line) - len(line.lstrip()) for line in lines if line.strip()),
default=0,
)
cleaned = [line[min_indent:] if line.strip() else "" for line in lines]
return "\n".join(cleaned).strip()
def _get_clean_operation_description(parsed_doc: Any) -> str:
"""
生成干净的 operation description。
策略:保留 summary + long_description,去掉 Args/Returns/Raises 等机器块。
"""
parts: list[str] = []
short = getattr(parsed_doc, "short_description", None)
long_ = getattr(parsed_doc, "long_description", None)
if short:
parts.append(short)
if long_:
parts.append(long_)
return "\n\n".join(parts).strip()
def _inject_schema_properties(
schema: Dict[str, Any],
param_lookup: Dict[str, str],
visited_refs: Optional[Set[str]] = None,
openapi_schema: Optional[Dict[str, Any]] = None,
) -> None:
"""
递归注入 schema properties 的描述。
支持对象、数组、allOf/anyOf/oneOf、$ref 引用(全局 components/schemas 补全)。
"""
if visited_refs is None:
visited_refs = set()
if not isinstance(schema, dict):
return
# 处理 $ref:在 components/schemas 中查找并补全
ref = schema.get("$ref")
if ref and openapi_schema:
if ref not in visited_refs:
visited_refs.add(ref)
# 提取 schema 名,例如 "#/components/schemas/User" -> "User"
schema_name = ref.split("/")[-1]
components = openapi_schema.get("components", {}).get("schemas", {})
target = components.get(schema_name)
if target:
_inject_schema_properties(target, param_lookup, visited_refs, openapi_schema)
return
# 处理 properties(对象字段)
properties = schema.get("properties")
if isinstance(properties, dict):
for prop_name, prop_schema in properties.items():
if prop_name in param_lookup:
# 只有当 docstring 描述非空时才写入
if param_lookup[prop_name]:
prop_schema["description"] = param_lookup[prop_name]
# 递归处理子 schema
_inject_schema_properties(prop_schema, param_lookup, visited_refs, openapi_schema)
# 处理 items(数组类型)
items = schema.get("items")
if items:
_inject_schema_properties(items, param_lookup, visited_refs, openapi_schema)
# 处理 allOf / anyOf / oneOf
for key in ("allOf", "anyOf", "oneOf"):
for sub in schema.get(key, []):
_inject_schema_properties(sub, param_lookup, visited_refs, openapi_schema)
# 处理 additionalProperties
additional = schema.get("additionalProperties")
if isinstance(additional, dict):
_inject_schema_properties(additional, param_lookup, visited_refs, openapi_schema)
def enrich_openapi_from_docstrings(
app: FastAPI,
*,
prefer_docstring_over_field: bool = True,
append_raises_to_description: bool = True,
docstring_style: DocstringStyle = DocstringStyle.AUTO,
) -> None:
"""
为 FastAPI 应用启用 docstring 驱动的 OpenAPI 增强。
参数
----
app : FastAPI
目标应用实例。
prefer_docstring_over_field : bool, 默认 True
当 docstring 中的参数描述与 Pydantic Field(description=...) 冲突时,
是否优先使用 docstring 的描述。
append_raises_to_description : bool, 默认 True
是否将 Raises 段落以 Markdown 格式追加到 operation description。
docstring_style : DocstringStyle, 默认 AUTO
解析风格。团队统一用 Google 时可显式传入 ``DocstringStyle.GOOGLE``。
"""
# 保存原始的 openapi 函数(如果有)
original_openapi = app.openapi
def custom_openapi() -> Dict[str, Any]:
# 如果已经有缓存,直接返回
if app.openapi_schema:
return app.openapi_schema
# 生成基础 schema
openapi_schema = get_openapi(
title=app.title,
version=app.version,
openapi_version=app.openapi_version,
description=app.description,
routes=app.routes,
)
for route in app.routes:
if not hasattr(route, "endpoint") or not route.endpoint:
continue
path = getattr(route, "path", None)
methods = [m.lower() for m in route.methods] if hasattr(route, "methods") else []
if not path or not methods:
continue
# 解析 docstring
parsed = _parse_docstring(route.endpoint, style=docstring_style)
if not parsed:
continue
param_lookup = _build_param_lookup(parsed)
returns_desc = _build_returns_description(parsed)
raises_desc = _build_raises_description(parsed)
clean_desc = _get_clean_operation_description(parsed)
for method in methods:
if method == "head":
# FastAPI 通常不把 HEAD 单独写入 OpenAPI,或者与 GET 共享
continue
if method not in openapi_schema.get("paths", {}).get(path, {}):
continue
op = openapi_schema["paths"][path][method]
# ---------- 1. 更新 operation description ----------
if clean_desc:
op["description"] = clean_desc
# ---------- 2. 注入参数描述(路径/查询/Header/Cookie----------
for param in op.get("parameters", []):
param_name = param.get("name")
if param_name and param_name in param_lookup:
existing = param.get("description", "")
new_desc = param_lookup[param_name]
if new_desc and (prefer_docstring_over_field or not existing):
param["description"] = new_desc
# ---------- 3. 注入请求体 schema 字段描述 ----------
if "requestBody" in op:
content = op["requestBody"].get("content", {})
for media_obj in content.values():
schema = media_obj.get("schema", {})
if schema:
_inject_schema_properties(
schema, param_lookup, openapi_schema=openapi_schema
)
# ---------- 4. 注入返回值描述 ----------
if returns_desc:
for code, resp in op.get("responses", {}).items():
if code.startswith("2"): # 2xx 成功响应
# 更新响应级 description
resp["description"] = returns_desc
# 同时注入到响应 schema 的 description(如果存在)
for media_obj in resp.get("content", {}).values():
schema = media_obj.get("schema", {})
if schema and not schema.get("description"):
schema["description"] = returns_desc
# 递归注入 schema 内部字段
_inject_schema_properties(
schema, param_lookup, openapi_schema=openapi_schema
)
# ---------- 5. 异常描述追加 ----------
if append_raises_to_description and raises_desc:
current_desc = op.get("description", "")
raises_md = f"## 异常\n\n{raises_desc}"
# 避免重复追加
if raises_md not in current_desc:
op["description"] = f"{current_desc}\n\n{raises_md}".strip()
app.openapi_schema = openapi_schema
return app.openapi_schema
app.openapi = custom_openapi
# =============================================================================
# 完整使用示例
# =============================================================================
if __name__ == "__main__":
import json
from typing import Annotated, Optional
from fastapi import FastAPI, Path, Query
from pydantic import BaseModel, Field
# ---------- 定义 DTO ----------
class EditChatDto(BaseModel):
old_message: str = Field(..., description="原始消息内容")
new_message: str = Field(..., description="修改后的消息内容")
change: str = Field(..., description="变更类型")
class ReturnDto(BaseModel):
result: str = Field(..., description="操作结果")
content: str = Field(..., description="最新聊天记录内容")
# ---------- 创建应用 ----------
app = FastAPI(title="Chatroom API", version="1.0.0")
# 启用 docstring 增强(必须在注册路由之前或之后都可以,但要在生成 schema 之前)
enrich_openapi_from_docstrings(app)
# ---------- 注册路由 ----------
@app.post("/api/chatroom/{id_}/chat/edit/", response_model=ReturnDto)
async def edit_chatroom_chat(
id_: Annotated[str, Path(description="聊天室 ID")],
body: EditChatDto,
force: Annotated[Optional[bool], Query(description="是否强制覆盖")] = None,
) -> ReturnDto:
"""编辑聊天室消息。
此端点不负责调用 AI 生成输出,而是用于修改一条已经保存在聊天记录中的消息。
前端调用后应使用返回的 content 刷新当前聊天室界面。
Args:
id_: 聊天室唯一标识符,UUID 格式。
body: 编辑请求体,包含旧消息、新消息和变更类型。
force: 是否跳过冲突检测直接覆盖。
Returns:
ReturnDto: 操作结果,其中 result 字段表示状态,content 字段为最新聊天记录。
Raises:
HTTPException: 404 表明未找到聊天室。
HTTPException: 400 表明聊天记录匹配失败,未更新。
"""
return ReturnDto(result="ok", content="new content")
# ---------- 输出生成的 OpenAPI schema ----------
schema = app.openapi()
print(json.dumps(schema, indent=2, ensure_ascii=False))