我有TypeScript应用程序,我正在使用
Inversify for IoC.
我有一个连接类：
'use strict';
import { injectable } from 'inversify';
import { createConnection,Connection } from "typeorm";
import { Photo,PhotoMetadata,Author,Album } from '../index';
@injectable()
class DBConnectionManager {
public createPGConnection(): Promise<Connection> {
return createConnection({
driver: {
type: "postgres",host: "host",port: 5432,username: "username",password: "password",database: "username"
},entities: [
Photo,Album
],autoSchemaSync: true,});
}
}
export { DBConnectionManager };
在我创建连接后,我想将连接绑定到我的容器中：
kernel.bind<Connection>('DefaultConnection').toConstantValue(getConnectionManager().get());
然后我想把它注入另一个类：
import { injectable,inject } from 'inversify';
import { Connection,FindOptions } from "typeorm";
import { IGenericRepository,ObjectType } from '../index';
@injectable()
class GenericRepository<T> implements IGenericRepository<T> {
private connection: Connection;
private type: ObjectType<T>;
constructor( @inject('DefaultConnection') connection: Connection) {
this.connection = connection;
}
因此,在我的容器配置中,如何绑定需要等待CreateConnection的DefaultConnection
我可以做异步并等待,但我想知道是否有更清洁的方法来实现这一点在inversify
解决方法
Inversify 2.0包括对异步工厂的支持(AKA提供商)
提供者允许您按如下方式声明提供者：
container.bind<<DbClient>("DbClient").to(DbClientClass);
container.bind<interfaces.Provider<DbClient>>("Provider<DbClient>")
.toProvider<DbClient>((context) => {
return () => {
return new Promise<DbClient>((resolve,reject) => {
// Create instance
let dbClient = context.container.get<DbClient>("DbClient");
// Open DB connection
dbClient.initialize("//connection_string")
.then(() => {
resolve(dbClient);
})
.catch((e: Error) => {
reject(e);
});
});
};
});
然后您可以注入并使用提供程序.唯一的问题是它需要两步初始化：构造函数注入和async getDb()方法.
class UserRepository {
private _db: DbClient;
private _dbProvider: Provider<DbClient>;
// STEP 1
// Inject a provider of DbClient to the constructor
public constructor(
@inject("Provider<DbClient>") provider: Provider<DbClient>
) {
this._dbProvider = provider;
}
// STEP 2
// Get a DB instance using a provider
// Returns a cached DB instance if it has already been created
private async getDb() {
if (this._db) return this._db;
this._db = await this._dbProvider();
return Promise.resolve(this._db);
}
public async getUser(): Promise<Users[]>{
let db = await this.getDb();
return db.collections.user.get({});
}
public async deletetUser(id: number): Promise<boolean>{
let db = await this.getDb();
return db.collections.user.delete({ id: id });
}
}
我们正在研究new feature以简化异步值的注入.此功能将包含在inversify 3.0中：
class UserRepository {
// STEP 1
public constructor(
@inject("Provider<DbClient>") private provider: Provider<DbClient>
) {}
public async getUser(): Promise<Users[]>{
// STEP 2: (No initialization method is required)
let db = await this.provider.someFancyNameForProvideValue;
return db.collections.user.get({});
}
}
