electric-new-feature

此技能基于 electric-shapes、electric-proxy-auth 和 electric-schema-shapes。请先阅读这些内容。

Electric — 端到端实现新功能

设置

0. 在本地启动 Electric

# docker-compose.yml
services:
  postgres:
    image: postgres:17-alpine
    environment:
      POSTGRES_DB: electric
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: password
    ports:
      - '54321:5432'
    tmpfs:
      - /tmp
    command:
      - -c
      - listen_addresses=*
      - -c
      - wal_level=logical

  electric:
    image: electricsql/electric:latest
    environment:
      DATABASE_URL: postgresql://postgres:password@postgres:5432/electric?sslmode=disable
      ELECTRIC_INSECURE: true # Dev only — use ELECTRIC_SECRET in production
    ports:
      - '3000:3000'
    depends_on:
      - postgres

docker compose up -d

1. 创建 Postgres 表

CREATE TABLE todos (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id UUID NOT NULL,
  text TEXT NOT NULL,
  completed BOOLEAN DEFAULT false,
  created_at TIMESTAMPTZ DEFAULT now()
);

ALTER TABLE todos REPLICA IDENTITY FULL;

2. 创建代理路由

代理会转发 Electric 协议参数，并注入服务端密钥。请使用你所用框架的服务端路由模式（TanStack Start、Next.js API route、Express 等）。

// Example: TanStack Start — src/routes/api/todos.ts
import { createFileRoute } from '@tanstack/react-router'
import { ELECTRIC_PROTOCOL_QUERY_PARAMS } from '@electric-sql/client'

const serve = async ({ request }: { request: Request }) => {
  const url = new URL(request.url)
  const electricUrl = process.env.ELECTRIC_URL || 'http://localhost:3000'
  const origin = new URL(`${electricUrl}/v1/shape`)

  url.searchParams.forEach((v, k) => {
    if (ELECTRIC_PROTOCOL_QUERY_PARAMS.includes(k))
      origin.searchParams.set(k, v)
  })

  origin.searchParams.set('table', 'todos')

  // Add auth if using Electric Cloud
  if (process.env.ELECTRIC_SOURCE_ID && process.env.ELECTRIC_SECRET) {
    origin.searchParams.set('source_id', process.env.ELECTRIC_SOURCE_ID)
    origin.searchParams.set('secret', process.env.ELECTRIC_SECRET)
  }

  const res = await fetch(origin)
  const headers = new Headers(res.headers)
  headers.delete('content-encoding')
  headers.delete('content-length')
  return new Response(res.body, {
    status: res.status,
    statusText: res.statusText,
    headers,
  })
}

export const Route = createFileRoute('/api/todos')({
  server: {
    handlers: {
      GET: serve,
    },
  },
})

3. 定义 schema

// db/schema.ts — Zod schema matching your Postgres table
import { z } from 'zod'

export const todoSchema = z.object({
  id: z.string().uuid(),
  user_id: z.string().uuid(),
  text: z.string(),
  completed: z.boolean(),
  created_at: z.date(),
})

export type Todo = z.infer<typeof todoSchema>

如果使用 Drizzle，可通过 drizzle-zod 中的 createSelectSchema(todosTable) 从表定义生成 schema。

4. 创建 mutation 端点

使用你所用框架的服务端函数或 API route 实现写入端点。该端点必须从执行 mutation 的同一事务中返回 { txid }。

// Example: server function that inserts and returns txid
async function createTodo(todo: { text: string; user_id: string }) {
  const client = await pool.connect()
  try {
    await client.query('BEGIN')
    const result = await client.query(
      'INSERT INTO todos (text, user_id) VALUES ($1, $2) RETURNING id',
      [todo.text, todo.user_id]
    )
    const txResult = await client.query(
      'SELECT pg_current_xact_id()::xid::text AS txid'
    )
    await client.query('COMMIT')
    return { id: result.rows[0].id, txid: Number(txResult.rows[0].txid) }
  } finally {
    client.release()
  }
}

5. 创建 TanStack DB 集合

import { createCollection } from '@tanstack/react-db'
import { electricCollectionOptions } from '@tanstack/electric-db-collection'
import { todoSchema } from './db/schema'

export const todoCollection = createCollection(
  electricCollectionOptions({
    id: 'todos',
    schema: todoSchema,
    getKey: (row) => row.id,
    shapeOptions: {
      url: new URL(
        '/api/todos',
        typeof window !== 'undefined'
          ? window.location.origin
          : 'http://localhost:5173'
      ).toString(),
      // Electric auto-parses: bool, int2, int4, float4, float8, json, jsonb
      // You only need custom parsers for types like timestamptz, date, numeric
      // See electric-shapes/references/type-parsers.md for the full list
      parser: {
        timestamptz: (date: string) => new Date(date),
      },
    },
    onInsert: async ({ transaction }) => {
      const { modified: newTodo } = transaction.mutations[0]
      const result = await createTodo({
        text: newTodo.text,
        user_id: newTodo.user_id,
      })
      return { txid: result.txid }
    },
    onUpdate: async ({ transaction }) => {
      const { modified: updated } = transaction.mutations[0]
      const result = await updateTodo(updated.id, {
        text: updated.text,
        completed: updated.completed,
      })
      return { txid: result.txid }
    },
    onDelete: async ({ transaction }) => {
      const { original: deleted } = transaction.mutations[0]
      const result = await deleteTodo(deleted.id)
      return { txid: result.txid }
    },
  })
)

6. 构建实时查询

import { useLiveQuery, eq } from '@tanstack/react-db'

export function TodoList() {
  const { data: todos } = useLiveQuery((q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.completed, false))
      .orderBy(({ todo }) => todo.created_at, 'desc')
      .limit(50)
  )

  return (
    <ul>
      {todos.map((todo) => (
        <li key={todo.id}>{todo.text}</li>
      ))}
    </ul>
  )
}

7. 乐观 mutation

const handleAdd = () => {
  todoCollection.insert({
    id: crypto.randomUUID(),
    text: 'New todo',
    completed: false,
    created_at: new Date(),
  })
}

const handleToggle = (todo) => {
  todoCollection.update(todo.id, (draft) => {
    draft.completed = !draft.completed
  })
}

const handleDelete = (todoId) => todoCollection.delete(todoId)

常见错误

高优先级：因 TanStack DB schema 会处理类型而移除解析器

错误：

// "My Zod schema has z.coerce.date() so I don't need a parser"
electricCollectionOptions({
  schema: z.object({ created_at: z.coerce.date() }),
  shapeOptions: { url: '/api/todos' }, // No parser!
})

正确：

electricCollectionOptions({
  schema: z.object({ created_at: z.coerce.date() }),
  shapeOptions: {
    url: '/api/todos',
    parser: { timestamptz: (date: string) => new Date(date) },
  },
})

Electric 的同步路径会将数据直接写入集合存储，绕过 TanStack DB schema。shapeOptions 中的 parser 负责在同步路径上进行类型强制转换；schema 则处理 mutation 路径。两者都不可缺少。如果没有 parser，timestamptz 会以字符串形式传入，导致 getTime() 或其他 Date 方法在运行时失败。

严重：使用旧版 electrify() 双向同步 API

错误：

const { db } = await electrify(conn, schema)
await db.todos.create({ text: 'New todo' })

正确：

todoCollection.insert({ id: crypto.randomUUID(), text: 'New todo' })
// Write path: collection.insert() → onInsert → API → Postgres → txid → awaitTxId

旧版 ElectricSQL（v0.x）支持 SQLite 双向同步。当前版本的 Electric 为只读。写入通过 API 端点完成，并通过 txid 握手机制进行协调。

来源：AGENTS.md:386-392

高优先级：使用基于路径的表 URL 模式

错误：

const stream = new ShapeStream({
  url: 'http://localhost:3000/v1/shape/todos?offset=-1',
})

正确：

const stream = new ShapeStream({
  url: 'http://localhost:3000/v1/shape?table=todos&offset=-1',
})

将表名作为路径段的模式（/v1/shape/todos）已在 v0.8.0 中移除。现在表名是查询参数。

来源：packages/sync-service/CHANGELOG.md:1124

中优先级：使用 shape_id 而不是 handle

错误：

const stream = new ShapeStream({
  url: '/api/todos',
  params: { shape_id: '12345' },
})

正确：

const stream = new ShapeStream({
  url: '/api/todos',
  handle: '12345',
})

此名称在 v0.8.0 中从 shape_id 更改为 handle。

另请参阅：electric-orm/SKILL.md — 从 ORM 事务中获取 txid。 另请参阅：electric-proxy-auth/SKILL.md — 端到端功能流程包含设置代理路由。

版本

目标版本：@electric-sql/client v1.5.10、@tanstack/react-db 最新版。