带有蒸气2的服务器端Swift（第1部分）
在2015年Swift开源之前，我曾尝试用Node.js编写一个简单的RESTful API服务器。 但是，由于我对Javascript语法和后端开发不熟悉，所以没有足够的时间来深入研究。 如今，有几种不同的服务器端Swift框架，例如Vapor，Perfect和Kitura。 作为iOS开发人员，这是拓展后端开发视野的好机会。
根据其GitHub页面，Vapor是Swift最常用的Web框架。 它为您的下一个网站，API或云项目提供了精美而易用的基础。 更重要的是，raywenderlich.com网站上有一系列免费教程。 这些教程为我提供了如何使用Vapor构建API服务器的基本概念，即使它们是在先前版本中完成的。 谢谢雷！
在本文中，我将演示一个简单的RESTful API服务器，该服务器将处理三种模型： Lesson ， Teacher和Student 。 基本上，我们需要以下端点：
-
/{models}：通过GET请求获取所有模型对象，或者通过带有JSON正文的POST请求创建新的模型对象。 （只需将{models}替换为课程，教师和学生。） -
/{models}/id：通过GET请求获取特定的模型对象，通过DELETE请求删除一个模型对象，或通过带有JSON正文的PATCH请求更新现有模型对象。
在我们开始编码之前，有几种必要的配置。 首先，按照Vapor网站上的说明正确安装Vapor，然后使用vapor new your_project_name --template=api创建一个新项目。 其次，在该项目中，我选择使用PostgreSQL作为数据库服务器，因此有必要在Macbook上安装PostgreSQL，并将蒸气的PostgreSQL提供程序添加到我的项目依赖项中。 启动PostgreSQL服务器后，按如下所示打开并修改Package.swift文件。
let package = Package( // ... dependencies: [ .Package(url: "https://github.com/vapor/vapor.git", majorVersion: 2), .Package(url: "https://github.com/vapor-community/postgresql-provider.git", majorVersion: 2) ], // ... )
然后，在目录Config/secrets下创建一个名为postgresql.json的新文件，并将以下代码片段添加到postgresql.json文件中。
{ "hostname": your_host_address, "user": your_username, "password": your_password, "database": your_database_name, "port": 5432 }
请记住用以下命令替换Config/fluent.json的驱动程序。
"driver": "postgresql"
最后一步是在Config+Setup.swift文件中添加PostgreSQL提供程序。
import PostgreSQLProviderextension Config { // ... private func setupProviders() throws { try addProvider(FluentProvider.Provider.self) try addProvider(PostgreSQLProvider.Provider.self) } // ... }extension Config { // ... private func setupProviders() throws { try addProvider(FluentProvider.Provider.self) try addProvider(PostgreSQLProvider.Provider.self) } // ... }
完成所有配置后，使用vapor build和vapor xcode获取必要的依赖关系并生成一个新的Xcode项目。
首先让我们处理模型类。 打开我们在上一步中生成的Xcode项目，然后将Lesson.swift ， Teacher.swift和Student.swift文件添加到Models组中。 在将新文件添加到我们的项目时，请确保选择目标为App。
此外，请按照Vapor的文档正确定义我们的模型。 因为它们的实现非常相似，所以我只显示Lesson.swift如下。
import PostgreSQLProviderfinal class Lesson: Model { let storage = Storage() // This is for Storable protocolfinal class Lesson: Model { let storage = Storage() // This is for Storable protocolfinal class Lesson: Model { let storage = Storage() // This is for Storable protocolvar title: String// Use these keys instead of magic strings static let idKey = "id" static let titleKey = "title"// Use these keys instead of magic strings static let idKey = "id" static let titleKey = "title"// Use these keys instead of magic strings static let idKey = "id" static let titleKey = "title"init(title: String) { self.title = title }init(title: String) { self.title = title }init(title: String) { self.title = title }init(row: Row) throws { self.title = try row.get(Lesson.titleKey) }init(row: Row) throws { self.title = try row.get(Lesson.titleKey) }init(row: Row) throws { self.title = try row.get(Lesson.titleKey) }func makeRow() throws -> Row { var row = Row() try row.set(Lesson.titleKey, title) return row } }func makeRow() throws -> Row { var row = Row() try row.set(Lesson.titleKey, title) return row } }func makeRow() throws -> Row { var row = Row() try row.set(Lesson.titleKey, title) return row } }// For database prepare and revert extension Lesson: Preparation { static func prepare(_ database: Database) throws { try database.create(self) { (user) in user.id() user.string(Lesson.titleKey) } }// For database prepare and revert extension Lesson: Preparation { static func prepare(_ database: Database) throws { try database.create(self) { (user) in user.id() user.string(Lesson.titleKey) } }// For database prepare and revert extension Lesson: Preparation { static func prepare(_ database: Database) throws { try database.create(self) { (user) in user.id() user.string(Lesson.titleKey) } }static func revert(_ database: Database) throws { try database.delete(self) } }static func revert(_ database: Database) throws { try database.delete(self) } }static func revert(_ database: Database) throws { try database.delete(self) } }// Convenience of generate model from JSON extension Lesson: JSONConvertible { convenience init(json: JSON) throws { self.init(title: try json.get(Lesson.titleKey)) }// Convenience of generate model from JSON extension Lesson: JSONConvertible { convenience init(json: JSON) throws { self.init(title: try json.get(Lesson.titleKey)) }// Convenience of generate model from JSON extension Lesson: JSONConvertible { convenience init(json: JSON) throws { self.init(title: try json.get(Lesson.titleKey)) }func makeJSON() throws -> JSON { var json = JSON() try json.set(Lesson.idKey, id?.string) try json.set(Lesson.titleKey, title) return json } }func makeJSON() throws -> JSON { var json = JSON() try json.set(Lesson.idKey, id?.string) try json.set(Lesson.titleKey, title) return json } }func makeJSON() throws -> JSON { var json = JSON() try json.set(Lesson.idKey, id?.string) try json.set(Lesson.titleKey, title) return json } }// Convenience of returning response extension Lesson: ResponseRepresentable {}// Convenience of returning response extension Lesson: ResponseRepresentable {}
创建模型后，切换到Config+Setup.swift文件并添加准备。
private func setupPreparations() throws { preparations.append(Lesson.self) preparations.append(Teacher.self) preparations.append(Student.self) }
接下来，也将与我们的模型相对应的控制器添加到Controllers组中。 在每个控制器内部，我们可以利用Vapor的ResourceRepresentable协议的优势来处理模型的CRUD。 再次，为简单起见，我仅显示以下内容的LessonController.swift实现。
import PostgreSQLProviderfinal class LessonController { fileprivate func getAll(request: Request) throws -> ResponseRepresentable { return try Lesson.all().makeJSON() }final class LessonController { fileprivate func getAll(request: Request) throws -> ResponseRepresentable { return try Lesson.all().makeJSON() }final class LessonController { fileprivate func getAll(request: Request) throws -> ResponseRepresentable { return try Lesson.all().makeJSON() }fileprivate func getOne(request: Request, lesson: Lesson) throws -> ResponseRepresentable { return lesson }fileprivate func getOne(request: Request, lesson: Lesson) throws -> ResponseRepresentable { return lesson }fileprivate func getOne(request: Request, lesson: Lesson) throws -> ResponseRepresentable { return lesson }fileprivate func create(request: Request) throws -> ResponseRepresentable { let lesson = try request.lesson() try lesson.save() return lesson }fileprivate func create(request: Request) throws -> ResponseRepresentable { let lesson = try request.lesson() try lesson.save() return lesson }fileprivate func create(request: Request) throws -> ResponseRepresentable { let lesson = try request.lesson() try lesson.save() return lesson }fileprivate func update(request: Request, lesson: Lesson) throws -> ResponseRepresentable { let newLesson = try request.lesson() lesson.title = newLesson.title try lesson.save() return lesson }fileprivate func update(request: Request, lesson: Lesson) throws -> ResponseRepresentable { let newLesson = try request.lesson() lesson.title = newLesson.title try lesson.save() return lesson }fileprivate func update(request: Request, lesson: Lesson) throws -> ResponseRepresentable { let newLesson = try request.lesson() lesson.title = newLesson.title try lesson.save() return lesson }fileprivate func delete(request: Request, lesson: Lesson) throws -> ResponseRepresentable { try lesson.delete() return lesson } }fileprivate func delete(request: Request, lesson: Lesson) throws -> ResponseRepresentable { try lesson.delete() return lesson } }fileprivate func delete(request: Request, lesson: Lesson) throws -> ResponseRepresentable { try lesson.delete() return lesson } }// Notice the difference between Item and Muliple extension LessonController: ResourceRepresentable { func makeResource() -> Resource { return Resource( index: getAll, store: create, show: getOne, update: update, destroy: delete ) } }// Notice the difference between Item and Muliple extension LessonController: ResourceRepresentable { func makeResource() -> Resource { return Resource( index: getAll, store: create, show: getOne, update: update, destroy: delete ) } }// Notice the difference between Item and Muliple extension LessonController: ResourceRepresentable { func makeResource() -> Resource { return Resource( index: getAll, store: create, show: getOne, update: update, destroy: delete ) } }// Convenience of retrieving Lesson object extension Request { fileprivate func lesson() throws -> Lesson { guard let json = json else { throw Abort.badRequest }// Convenience of retrieving Lesson object extension Request { fileprivate func lesson() throws -> Lesson { guard let json = json else { throw Abort.badRequest }// Convenience of retrieving Lesson object extension Request { fileprivate func lesson() throws -> Lesson { guard let json = json else { throw Abort.badRequest }return try Lesson(json: json) } }return try Lesson(json: json) } }
最后，通过Router.swift添加到Router.swift文件中，连接我们的控制器和Droplet对象。
func setupRoutes() throws { let lessonController = LessonController() resource("lessons", lessonController)func setupRoutes() throws { let lessonController = LessonController() resource("lessons", lessonController)let teacherController = TeacherController() resource("teachers", teacherController)let teacherController = TeacherController() resource("teachers", teacherController)let teacherController = TeacherController() resource("teachers", teacherController)let studentController = StudentController() resource("students", studentController) }let teacherController = TeacherController() resource("teachers", teacherController)let studentController = StudentController() resource("students", studentController) }let studentController = StudentController() resource("students", studentController) }
至此，我们实现了一个简单的RESTful API服务器，并且可以使用Postman测试模型CRUD。 在本系列的第2部分中，我将演示如何在两个模型之间实现同级（多对多）关系。