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将 PostgreSQL 与 Nexy 一起使用

要将 PostgreSQL 与 Nexy 一起使用，请安装 psycopg 驱动程序，将 DATABASE_URL 设置为 postgresql+psycopg:// URL，并通过 SQLModel 或 SQLAlchemy 从处理程序和页面查询它。

本地运行 PostgreSQL

docker run --name nexy-db -e POSTGRES_PASSWORD=secret -e POSTGRES_DB=app -p 5432:5432 -d postgres:17

安装驱动程序

uv add "psycopg[binary]"

psycopg 是驱动程序的版本 3，用于同步和异步代码。对于仅异步代码，asyncpg 是另一个选择：

uv add asyncpg

连接字符串

.env
DATABASE_URL=postgresql+psycopg://postgres:secret@localhost:5432/app
网址 司机
postgresql+psycopg://user:pass@host:5432/db psycopg 3，同步和异步
postgresql+asyncpg://user:pass@host:5432/db asyncpg，仅异步
postgresql://user:pass@host:5432/db psycopg2，如果已安装
postgres://... 被 SQLAlchemy 拒绝：将方案重命名为 postgresql+psycopg://

包含 @、: 或 / 的密码在 URL 中进行百分比编码：p@ss 为 p%40ss。

发动机

托管平台通常会分发 postgres:// URL。在引擎制造地对其进行转换：

src/configs/db.py
import os from dotenv import load_dotenvfrom sqlmodel import create_engine load_dotenv()  def database_url() -> str:    url = os.environ["DATABASE_URL"]    return url.replace("postgres://", "postgresql+psycopg://", 1)  engine = create_engine(database_url(), pool_size=5, max_overflow=10, pool_pre_ping=True)
池选项 它的作用
pool_size=5 每个进程的连接保持打开状态
max_overflow=10 负载下允许额外连接，之后关闭
pool_pre_ping=True 使用前检查连接，重启数据库不会报错

每个 nx start 工作线程都有自己的池：workers × (pool_size + max_overflow) 必须保留在服务器的 max_connections 下。

具有 PostgreSQL 类型的模型

uuid 键、JSONB、数组和 timestamptz 是本机列类型：

src/models/post_model.py
import uuidfrom datetime import datetime, timezone from sqlalchemy import Column, DateTime, Stringfrom sqlalchemy.dialects.postgresql import ARRAY, JSONBfrom sqlmodel import Field, SQLModel  class Post(SQLModel, table=True):    id: uuid.UUID = Field(default_factory=uuid.uuid4, primary_key=True)    title: str = Field(max_length=200, index=True)    tags: list[str] = Field(default_factory=list, sa_column=Column(ARRAY(String)))    extra: dict = Field(default_factory=dict, sa_column=Column(JSONB))    published_at: datetime = Field(        default_factory=lambda: datetime.now(timezone.utc),        sa_column=Column(DateTime(timezone=True)),    )

每个请求一个会话

src/configs/session.py
from collections.abc import Iterator from sqlmodel import Session from src.configs.db import engine  def get_session() -> Iterator[Session]:    with Session(engine) as session:        yield session

从处理程序读取和写入

src/routes/api/posts/index.py
from pydantic import BaseModelfrom sqlmodel import Session, select from nexy.http import Depends, JSONResponsefrom src.configs.session import get_sessionfrom src.models.post_model import Post  class NewPost(BaseModel):    title: str    tags: list[str] = []  async def GET(tag: str | None = None, session: Session = Depends(get_session)):    query = select(Post).order_by(Post.published_at.desc())    if tag:        query = query.where(Post.tags.contains([tag]))    return session.exec(query).all()  async def POST(body: NewPost, session: Session = Depends(get_session)):    post = Post(title=body.title, tags=body.tags)    session.add(post)    session.commit()    session.refresh(post)    return JSONResponse(post.model_dump(mode="json"), status_code=201)
src/apps/posts/posts_api_controller.py
from pydantic import BaseModelfrom sqlmodel import Session, select from nexy.decorators import Controllerfrom nexy.http import Depends, JSONResponsefrom src.configs.session import get_sessionfrom src.models.post_model import Post  class NewPost(BaseModel):    title: str    tags: list[str] = []  @Controller("/api/posts")class PostsApiController:    async def get(self, tag: str | None = None, session: Session = Depends(get_session)):        query = select(Post).order_by(Post.published_at.desc())        if tag:            query = query.where(Post.tags.contains([tag]))        return session.exec(query).all()     async def post(self, body: NewPost, session: Session = Depends(get_session)):        post = Post(title=body.title, tags=body.tags)        session.add(post)        session.commit()        session.refresh(post)        return JSONResponse(post.model_dump(mode="json"), status_code=201)

在根模块的 controllers 中列出控制器。

Post.tags.contains([tag]) 是 PostgreSQL 的 @>：标签包含 tag 的帖子。

URL 中的 uuid

src/routes/api/posts/[id].py
import uuid from sqlmodel import Session from nexy.http import Depends, HTTPExceptionfrom src.configs.session import get_sessionfrom src.models.post_model import Post  async def GET(id: uuid.UUID, session: Session = Depends(get_session)):    post = session.get(Post, id)    if post is None:        raise HTTPException(status_code=404, detail="No such post")    return post
src/apps/posts/posts_by_id_api_controller.py
import uuid from sqlmodel import Session from nexy.decorators import Controllerfrom nexy.http import Depends, HTTPExceptionfrom src.configs.session import get_sessionfrom src.models.post_model import Post  @Controller("/api/posts/{id}")class PostsByIdApiController:    async def get(self, id: uuid.UUID, session: Session = Depends(get_session)):        post = session.get(Post, id)        if post is None:            raise HTTPException(status_code=404, detail="No such post")        return post

在根模块的 controllers 中列出控制器。

非 UUID 的段在查询运行之前回答 404。

查询 JSONB

src/services/posts.py
from sqlmodel import Session, select from src.configs.db import enginefrom src.models.post_model import Post  def featured_posts() -> list[Post]:    with Session(engine) as session:        query = select(Post).where(Post.extra["featured"].as_boolean())        return list(session.exec(query))
src/routes/featured.nexy
---from src.services.posts import featured_posts posts = featured_posts()---<ul>  {% for post in posts %}  <li>{{ post.title | e }}</li>  {% endfor %}</ul>
src/apps/featured/featured_view.nexy
---from src.services.posts import featured_posts posts = featured_posts()---<ul>  {% for post in posts %}  <li>{{ post.title | e }}</li>  {% endfor %}</ul>
src/apps/featured/featured_controller.py
from nexy.decorators import Controllerfrom nexy.hooks import useViews  @Controller("/featured")class FeaturedController:    async def get(self):        return useViews("src/apps/featured/featured_view.nexy")

将查询保留在函数中：只有在 frontmatter 顶层分配的名称才能到达模板。

全文检索

src/routes/api/search.py
from sqlalchemy import funcfrom sqlmodel import Session, select from nexy.http import Dependsfrom src.configs.session import get_sessionfrom src.models.post_model import Post  async def GET(q: str, session: Session = Depends(get_session)):    document = func.to_tsvector("english", Post.title)    query = func.websearch_to_tsquery("english", q)    rank = func.ts_rank(document, query)    rows = session.exec(select(Post).where(document.op("@@")(query)).order_by(rank.desc()))    return rows.all()
src/apps/search/search_api_controller.py
from sqlalchemy import funcfrom sqlmodel import Session, select from nexy.decorators import Controllerfrom nexy.http import Dependsfrom src.configs.session import get_sessionfrom src.models.post_model import Post  @Controller("/api/search")class SearchApiController:    async def get(self, q: str, session: Session = Depends(get_session)):        document = func.to_tsvector("english", Post.title)        query = func.websearch_to_tsquery("english", q)        rank = func.ts_rank(document, query)        rows = session.exec(select(Post).where(document.op("@@")(query)).order_by(rank.desc()))        return rows.all()

在根模块的 controllers 中列出控制器。

索引可以在大表上保持快速。将其添加到迁移中：

alembic/版本/xxxx_search_index.py
def upgrade() -> None:    op.execute(        "CREATE INDEX post_title_search ON post USING GIN (to_tsvector('english', title))"    )

更新插入

src/services/tags.py
from sqlalchemy.dialects.postgresql import insertfrom sqlmodel import Field, Session, SQLModel from src.configs.db import engine  class TagCount(SQLModel, table=True):    tag: str = Field(primary_key=True)    count: int = 0  def count_tag(tag: str) -> None:    statement = insert(TagCount).values(tag=tag, count=1)    statement = statement.on_conflict_do_update(        index_elements=[TagCount.tag], set_={"count": TagCount.count + 1}    )    with Session(engine) as session:        session.exec(statement)        session.commit()

迁移

nx migrate --initnx migrate -m "create posts"nx migrate --upgrade

nx migrate 读取 DATABASE_URL，检查驱动程序是否已安装以及服务器是否应答，然后运行 Alembic。导入 alembic/env.py 中的每个模型模块，以便自动生成可以看到它。

与 asyncpg 异步

src/configs/async_db.py
from sqlalchemy.ext.asyncio import create_async_enginefrom sqlmodel.ext.asyncio.session import AsyncSession from src.configs.db import database_url async_engine = create_async_engine(    database_url().replace("+psycopg", "+asyncpg", 1), pool_pre_ping=True)  async def get_async_session():    async with AsyncSession(async_engine) as session:        yield session
src/routes/api/posts/count.py
from sqlmodel import func, selectfrom sqlmodel.ext.asyncio.session import AsyncSession from nexy.http import Dependsfrom src.configs.async_db import get_async_sessionfrom src.models.post_model import Post  async def GET(session: AsyncSession = Depends(get_async_session)):    count = (await session.exec(select(func.count()).select_from(Post))).one()    return {"count": count}
src/apps/posts/posts_count_api_controller.py
from sqlmodel import func, selectfrom sqlmodel.ext.asyncio.session import AsyncSession from nexy.decorators import Controllerfrom nexy.http import Dependsfrom src.configs.async_db import get_async_sessionfrom src.models.post_model import Post  @Controller("/api/posts/count")class PostsCountApiController:    async def get(self, session: AsyncSession = Depends(get_async_session)):        count = (await session.exec(select(func.count()).select_from(Post))).one()        return {"count": count}

列出根模块的 controllers 中的控制器，在 PostsByIdApiController 之前：路径与答案匹配的第一个控制器，在其后面列出 /api/posts/count/ 答案 404。

psycopg 3 也运行异步：postgresql+psycopg:// 也可以与 create_async_engine 一起使用。

在事务中进行测试

每个测试都在回滚的事务内运行，因此测试数据库保持为空：

测试/conftest.py
import pytestfrom sqlmodel import Session, SQLModel, create_engine from nexy.app import appfrom src.configs.session import get_session test_engine = create_engine("postgresql+psycopg://postgres:secret@localhost:5432/app_test")SQLModel.metadata.create_all(test_engine)  @pytest.fixture(autouse=True)def session():    connection = test_engine.connect()    transaction = connection.begin()    session = Session(bind=connection, join_transaction_mode="create_savepoint")    app.dependency_overrides[get_session] = lambda: session    yield session    session.close()    transaction.rollback()    connection.close()

管理 PostgreSQL

服务 有什么变化
霓虹灯 添加 ?sslmode=require；使用池主机进行许多短连接
苏帕贝斯 相同的 URL 形式；对许多工作人员使用池化端口 6543
亚马逊 RDS、云 SQL、Azure 添加 ?sslmode=require，并允许应用程序的网络

后续步骤

在 GitHub 上编辑

Enter 打开结果，Esc 关闭。