如何在 inversify 中注入异步依赖?
How to inject an asynchronous dependency in inversify?
我有 TypeScript 应用程序,我正在使用 Inversify IoC。
我有连接class:
'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, PhotoMetadata, Author, Album
],
autoSchemaSync: true,
});
}
}
export { DBConnectionManager };
创建连接后,我想将一个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class:
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;
}
所以在我的容器配置中,如何绑定需要等待 CreateConnection 的 DefaultConnection
我可以使用 async 和 wait,但我想知道在 inversify
中是否有更简洁的方法来实现此目的
Inversify 2.0 包括对异步工厂(AKA Providers)的支持
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);
});
});
};
});
然后您可以注入和使用提供程序。唯一的问题是它需要两步初始化:constructor
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({});
}
}
只需在应用程序启动时创建连接并绑定已连接的实例,通常您不需要延迟连接。
我有 TypeScript 应用程序,我正在使用 Inversify IoC。
我有连接class:
'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, PhotoMetadata, Author, Album
],
autoSchemaSync: true,
});
}
}
export { DBConnectionManager };
创建连接后,我想将一个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class:
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;
}
所以在我的容器配置中,如何绑定需要等待 CreateConnection 的 DefaultConnection 我可以使用 async 和 wait,但我想知道在 inversify
中是否有更简洁的方法来实现此目的Inversify 2.0 包括对异步工厂(AKA Providers)的支持
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);
});
});
};
});
然后您可以注入和使用提供程序。唯一的问题是它需要两步初始化:constructor
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({});
}
}
只需在应用程序启动时创建连接并绑定已连接的实例,通常您不需要延迟连接。