Vapor 3 PostgreSQL CRUD无请求http

Question

我使用Xcode11.2和Swift 5.1创建基于Vapor 3.1.10的后端，数据库是PostgreSQL 12。我有一个问题:如何在没有POST和GET请求的情况下与数据库(CRUD)交互。所有教程都展示了如何通过HTTPS仅根据请求进行CRUD。但是，如果我的应用程序需要在不与网络交互的情况下在数据库中保存某些内容，该怎么办？看看我的代码：

import Vapor
import FluentPostgreSQL

final class Device: PostgreSQLModel {        
    var id: Int?
    var isWorking: Bool
    var serial: Int

    init(isWorking: Bool, serial: Int) {
        self.isWorking = isWorking
        self.serial = serial
    }    
}
extension Device: Content {}
extension Device: Migration {}
extension Device: Parameter {}

经典的写或读方法是：

import Vapor

final class DeviceController {        
    func readAll(_ req: Request) throws -> Future<[Device]> {
        return Device.query(on: req).all()
    }

    func create(_ req: Request) throws -> Future<Device> {
        return try req.content.decode(Device.self).flatMap { device in
            return device.save(on: req)
        }
    }
}

如何替换req到另一个后台，安全线程，我可以在本地创建？

例如：

let device = Device(isWorking: true, serial: 54321)
device.save(on: <#T##DatabaseConnectable#>)

如何替代<#T##DatabaseConnectable#>？

我将感谢任何帮助或建议。

Answer 1

基于这个问题和答案(Is is possible to use Vapor 3 Postgres Fluent in a standalone script?)，我实现了如下CRUD：

import Vapor
import FluentPostgreSQL

final class Device: PostgreSQLModel {
    var id: Int?
    var isWorking: Bool
    var serial: Int

    init(isWorking: Bool, serial: Int) {
        self.isWorking = isWorking
        self.serial = serial
    }
}
extension Device: Content {}
extension Device: Migration {}
extension Device: Parameter {}

final class WorkWithPostgres {

    let databaseConfig = PostgreSQLDatabaseConfig(hostname: "localhost", port: 5432, username: "username", database: "testestest", password: nil)

    let database: PostgreSQLDatabase

    static let shared = WorkWithPostgres()

    private init() {
        database = PostgreSQLDatabase(config: databaseConfig)
    }

    func readAll<T: PostgreSQLModel>(postgreSQLModel: T.Type, completion: (([T]) -> Void)?) {
        let worker = MultiThreadedEventLoopGroup(numberOfThreads: 1)
        let conn = database.newConnection(on: worker)

        let _ = conn.map { connection in
            postgreSQLModel.query(on: connection).all().map { databaseData in
                worker.shutdownGracefully { _ in
                }

                completion?(databaseData)
            }
        }
    }

    func create<T: PostgreSQLModel>(postgreSQLModel: T) {
        let worker = MultiThreadedEventLoopGroup(numberOfThreads: 1)
        let conn = database.newConnection(on: worker)

        let _ = conn.map { connection in
            let _ = postgreSQLModel.save(on: connection).whenComplete {
                worker.shutdownGracefully { _ in
                }
            }
        }
    }

}

final class DeviceController {

    func readAll(completion: (([Device]) -> Void)?) {
        WorkWithPostgres.shared.readAll(postgreSQLModel: Device.self) { devices in
            completion?(devices)
        }
    }

    func create(isWorking: Bool, serial: Int) {
        let device = Device(isWorking: isWorking, serial: serial)

        WorkWithPostgres.shared.create(postgreSQLModel: device)
    }

}

它是有效的，但我不确定这是不是一个好的方法。有人知道吗？

Answer 2

Request是Container，它有eventLoop，它是DatabaseConnectable。

Application，它是Container，它有eventLoop，但它不是DatabaseConnectable。

如何使用Application进行数据库查询？

在任何Container上，您都可以获得到数据库的池连接，您可能会猜到这个连接就是DatabaseConnectable。

boot.swift中的查询示例

import Vapor
import FluentSQL
import FluentPostgreSQL

public func boot(_ app: Application) throws {
    let _ = app.requestPooledConnection(to: .psql).flatMap { conn in
        return User.query(conn).all().map { users in
            print("just found \(users.count) users")
        }.always {
            try? app.releasePooledConnection(conn, to: .psql)
        }
    }
}

上面的代码将通过Application容器中的.psql标识符请求到PostgreSQL的池连接，然后对该连接执行查询，然后在always块中将该连接释放回池。

从哪里获取后台任务的Container？

如果您使用https://github.com/vapor/jobs或https://github.com/MihaelIsaev/VaporCron，那么在任务声明中将有一个Container对象。

VaporCron示例

// in boot.swift
import Vapor
import VaporCron

/// Called after your application has initialized.
public func boot(_ app: Application) throws {
    scheduleTasks(on: app)
}

/// Scheduling Cron tasks
private func scheduleTasks(on app: Application) {
    do {
        _ = try VaporCron.schedule(Every1MinCheck.self, on: app)
    } catch {
        print("cron schedule error: \(error)")
    }
}

// in Every1MinCheck.swift
import Vapor
import VaporCron
import FluentSQL
import PostgreSQL

struct Every1MinCheck: VaporCronSchedulable {
    static var expression: String { return "*/1 * * * *" } // every 1 minute

    static func task(on container: VaporCronContainer) -> Future<Void> {
        return container.requestPooledConnection(to: .psql).flatMap { conn in
            return User.query(conn).all().map { users in
                print("just found \(users.count) users")
            }.always {
                try? container.releasePooledConnection(conn, to: .psql)
            }
        }
    }
}