带Schema初始化Drizzle ORM客户端遇TypeScript类型错误求助

问题代码 #

实体定义（schema.ts） #

// schema.ts
export const users = pgTable('users', {
  id: serial('id').primaryKey(),
  email: varchar('email', {length: 256}).notNull(),
});    

Drizzle客户端初始化（db.server.ts） #

// db.server.ts
import {PostgresJsDatabase, drizzle} from 'drizzle-orm/postgres-js';
import postgres from 'postgres';
import * as schema from './schema';

const queryClient = postgres("postgres://...");
const db: PostgresJsDatabase = drizzle(queryClient, {schema});

报错信息 #

Type 'PostgresJsDatabase<typeof import("/app/db/schema")>' is not assignable to type 'PostgresJsDatabase'.
  The types of '_.schema' are incompatible between these types.
    Type 'ExtractTablesWithRelations<typeof import(/app/db/schema")> | undefined' is not assignable to type 'ExtractTablesWithRelations<Record<string, never>> | undefined'.
      Type 'ExtractTablesWithRelations<typeof import("/app/db/schema")>' is not assignable to type 'ExtractTablesWithRelations<Record<string, never>>'.
        Property 'users' is incompatible with index signature.
          Type '{ tsName: "users"; dbName: "users"; columns: { id: PgColumn<{ name: "id"; tableName: "users"; dataType: "number"; columnType: "PgSerial"; data: number; driverParam: number; notNull: true; hasDefault: true; enumValues: undefined; baseColumn: never; }, {}, {}>; email: PgColumn<...>; }; relations: never; primaryKey: An...' is not assignable to type '{ tsName: string; dbName: never; columns: never; relations: Record<string, Relation<string>>; primaryKey: AnyColumn[]; }'.
            Types of property 'dbName' are incompatible.
              Type 'string' is not assignable to type 'never'.ts(2322)

解决方法 #

方法1：让TypeScript自动推断类型（推荐） #

去掉手动指定的PostgresJsDatabase类型声明，让TS自动根据传入的schema推断正确类型：

// db.server.ts
import { drizzle } from 'drizzle-orm/postgres-js';
import postgres from 'postgres';
import * as schema from './schema';

const queryClient = postgres("postgres://...");
const db = drizzle(queryClient, {schema});

处理后db会自动获得包含users表的类型支持，可正常使用db.query.users.findMany()语法。

方法2：显式传入schema泛型参数 #

如果一定要手动指定类型，需要将你的schema类型作为泛型参数传给PostgresJsDatabase：

// db.server.ts
import { PostgresJsDatabase, drizzle } from 'drizzle-orm/postgres-js';
import postgres from 'postgres';
import * as schema from './schema';

const queryClient = postgres("postgres://...");
const db: PostgresJsDatabase<typeof schema> = drizzle(queryClient, {schema});

问题根源 #

PostgresJsDatabase是泛型类型，不指定泛型参数时，默认使用空schema类型（Record<string, never>）。而你传入了包含users表的schema，导致类型不匹配。要么让TS自动推断，要么显式传入你的schema类型即可解决。

内容的提问来源于stack exchange，提问作者Janne