我一直使用TypeORM没有问题，但是当我尝试进行API调用时，突然出现了以下错误：
EntityMetadataNotFound: No metadata for "BusinessApplication" was found.
at new EntityMetadataNotFoundError (C:\Users\Robbie\Code\fit-society\node_modules\typeorm\error\EntityMetadataNotFoundError.js:10:28)
at Connection.getMetadata (C:\Users\Robbie\Code\fit-society\node_modules\typeorm\connection\Connection.js:336:19)
at EntityManager.<anonymous> (C:\Users\Robbie\Code\fit-society\node_modules\typeorm\entity-manager\EntityManager.js:459:44)
at step (C:\Users\Robbie\Code\fit-society\node_modules\tslib\tslib.js:136:27)
at Object.next (C:\Users\Robbie\Code\fit-society\node_modules\tslib\tslib.js:117:57)
at C:\Users\Robbie\Code\fit-society\node_modules\tslib\tslib.js:110:75
at new Promise (<anonymous>)
at Object.__awaiter (C:\Users\Robbie\Code\fit-society\node_modules\tslib\tslib.js:106:16)
at EntityManager.find (C:\Users\Robbie\Code\fit-society\node_modules\typeorm\entity-manager\EntityManager.js:456:24)
at module.exports../src/pages/api/business-applications/[id].ts.__webpack_exports__.default.Object (C:\Users\Robbie\Code\fit-society\.next\server\static\development\pages\api\business-applications\[id].js:1648:65)
at process._tickCallback (internal/process/next_tick.js:68:7)
当调用此代码时会发生这种情况：
import { BusinessApplication } from '../../../backend/all-entities';
import db from '../../../backend/database';
// in a function...
const manager = await db.getManager();
// in this case, req.data.id does equal "oldest"
const application: BusinessApplication | undefined =
req.data.id === 'oldest'
? (await manager.find(BusinessApplication, { order: { dateSubmitted: 'DESC' }, take: 1 }))[0]
: await manager.findOne(BusinessApplication, { where: { id: parseInt(req.data.id, 10) } });
if (application == null) throw createError(404, 'Business application not found');
return application;
在 backend/all-entities.ts 文件中：
/**
* This file exists to solve circular dependency problems with Webpack by explicitly specifying the module loading order.
* @see https://medium.com/visual-development/how-to-fix-nasty-circular-dependency-issues-once-and-for-all-in-javascript-typescript-a04c987cf0de
*/
import Account_ from './entities/Account';
export { default as Qualification } from './entities/Qualification';
export { default as EditableAccount } from './entities/EditableAccount';
export { default as EditableBusiness } from './entities/EditableBusiness';
export { default as Business } from './entities/Business';
export { default as BusinessApplication, SendableBusinessApplication } from './entities/BusinessApplication';
export { default as EditableCustomer } from './entities/EditableCustomer';
export { default as Customer } from './entities/Customer';
export { default as Offer } from './entities/Offer';
export { default as ProductOffer } from './entities/ProductOffer';
export { default as ServiceOffer } from './entities/ServiceOffer';
在backend/database.ts文件中：
import 'reflect-metadata';
import {
Connection,
ConnectionManager,
ConnectionOptions,
createConnection,
EntityManager,
getConnectionManager
} from 'typeorm';
import { Business, BusinessApplication, Customer, ProductOffer, ServiceOffer, Qualification } from './all-entities';
/**
* Database manager class
*/
class Database {
private connectionManager: ConnectionManager;
constructor() {
this.connectionManager = getConnectionManager();
}
private async getConnection(): Promise<Connection> {
const CONNECTION_NAME = 'default';
let connection: Connection;
if (this.connectionManager.has(CONNECTION_NAME)) {
connection = this.connectionManager.get(CONNECTION_NAME);
if (!connection.isConnected) {
connection = await connection.connect();
}
} else {
const connectionOptions: ConnectionOptions = {
name: CONNECTION_NAME,
type: 'postgres',
url: process.env.DATABASE_URL,
synchronize: true,
entities: [Business, BusinessApplication, Qualification, Customer, ProductOffer, ServiceOffer]
};
connection = await createConnection(connectionOptions);
}
return connection;
}
public getManager(): Promise<EntityManager> {
return this.getConnection().then(conn => conn.manager);
}
}
const db = new Database();
export default db;
在后端/entities/BusinessApplication.ts文件中：
import { IsIn, IsString, IsOptional } from 'class-validator';
import { Column, CreateDateColumn, Entity, PrimaryGeneratedColumn } from 'typeorm';
import { EditableBusiness } from '../all-entities';
class PasswordlessBusinessApplication extends EditableBusiness {
@Column()
@IsIn(['individual', 'company'])
type!: 'individual' | 'company';
@Column({ nullable: true })
@IsOptional()
@IsString()
fein?: string;
@Column({ nullable: true })
@IsOptional()
@IsString()
professionalCertificationUrl?: string;
}
@Entity()
export default class BusinessApplication extends PasswordlessBusinessApplication {
@PrimaryGeneratedColumn()
id!: number;
@CreateDateColumn()
dateSubmitted!: Date;
@Column()
@IsString()
passwordHash!: string;
}
/**
* A business application sent by the client, which contains a password instead of a password hash.
* Qualification objects do not require id or business.
*/
export class SendableBusinessApplication extends PasswordlessBusinessApplication {
@IsString()
password!: string;
}
从我所看到的情况来看，所有的导入都指向正确的文件，我导入了reflect-metadata，并在BusinessApplication类上放置了@Entity()修饰符。那么出了什么问题呢？值得注意的是，如果我将第一个文件中的await manager.find（BusinessApplication，...）更改为await manager.find（'BusinessApplication'，...），它就可以正常工作，但我不想这样做，因为我会失去智能提示。此外，在服务器初始化后的第一次操作时，不会发生此错误，但在Webpack进行热模块重新加载后会出现问题（这可能是在Next.js销毁页面或我更改代码后发生的）。