PromiseKit 6.0 迁移

Question

我决定在我的项目中将 PromiseKit pod form 4.5.x 升级到 6.x.x。在迁移过程中，我遇到了一个问题，我不能 100% 确定我是否以正确的方式解决了它。

看看我在 PromiseKit 4.5 中的示例代码：

func fetchSettings(forAnimalsGuids animalsGuids: [String]) -> Promise<[JSON]> {
    if animalsGuids.isEmpty {
        return .value([])
    }

    let packageSize = 100
    let animalsPackages = animalsGuids.chunked(chunkSize: packageSize)

    return when(fulfilled: animalsPackages.map({ animalsPackage -> Promise<[JSON]> in
        let predicates: [GatewayRequestFactoryHelper.Predicate] = animalsPackage.map({ .atomic(.equal("Animal.ObjectGuid", .string([=10=]))) })
        let predicate: GatewayRequestFactoryHelper.Predicate? = !predicates.isEmpty ? .or(predicates) : nil

        return gatewayConnector.fetchObjects(type: AnimalMilkSetting.self, predicate: predicate)
    }))
    .then { result in
        Promise(value: Array(result.joined()))
    }
}

与 Promise(value: Array(result.joined())) 一致，我得到了一个错误：

Argument labels '(value:)' do not match any available overloads

根据 PromiseKit 迁移指南 return Promise(value: foo) 已被替换为：return .value(foo)，因此我重构了我的代码：

func fetchAnimal(forAnimalsGuids animalsGuids: [String]) -> Promise<[JSON]> {
    if animalsGuids.isEmpty {
        return .value([])
    }

    let packageSize = 100
    let animalsPackages = animalsGuids.chunked(chunkSize: packageSize)

    return when(fulfilled: animalsPackages.map({ animalsPackage -> Promise<[JSON]> in
        let predicates: [GatewayRequestFactoryHelper.Predicate] = animalsPackage.map({ .atomic(.equal("Animal.ObjectGuid", .string([=11=]))) })
        let predicate: GatewayRequestFactoryHelper.Predicate? = !predicates.isEmpty ? .or(predicates) : nil

        return gatewayConnector.fetchObjects(type: AnimalMilkSetting.self, predicate: predicate)
    }))
    .then { result in
        .value(Array(result.joined()))
//      Promise(value: Array(result.joined()))
    }
}

没用。编译显示错误信息：

Cannot convert return expression of type 'Promise<_.T>' to return type 'Promise<[JSON]>'

我做了一些调整，最终找到了一个被我的编译器接受的解决方案：

func fetchAnimal(forAnimalsGuids animalsGuids: [String]) -> Promise<[JSON]> {
    if animalsGuids.isEmpty {
        return .value([])
    }

    let packageSize = 100
    let animalsPackages = animalsGuids.chunked(chunkSize: packageSize)

    return when(fulfilled: animalsPackages.map({ animalsPackage -> Promise<[JSON]> in
        let predicates: [GatewayRequestFactoryHelper.Predicate] = animalsPackage.map({ .atomic(.equal("Animal.ObjectGuid", .string([=12=]))) })
        let predicate: GatewayRequestFactoryHelper.Predicate? = !predicates.isEmpty ? .or(predicates) : nil

        return gatewayConnector.fetchObjects(type: AnimalMilkSetting.self, predicate: predicate)
    }))
    .then { result in
        Promise { [=12=].fulfill(Array(result.joined())) }
    }
}

你能给我一个答案吗？我是否以正确的方式迁移了它？方式.value(Array(result.joined()))行不通？

Answer 1

我想我自己找到了答案。我使用了 PromiseKit 6 中引入的 map。来自文档：

map is fed the previous promise value and requires you return a non-promise, ie. a value.

所以：

func fetchAnimal(forAnimalsGuids animalsGuids: [String]) -> Promise<[JSON]> {
    if animalsGuids.isEmpty {
        return .value([])
    }

    let packageSize = 100
    let animalsPackages = animalsGuids.chunked(chunkSize: packageSize)

    return when(fulfilled: animalsPackages.map({ animalsPackage -> Promise<[JSON]> in
        let predicates: [GatewayRequestFactoryHelper.Predicate] = animalsPackage.map({ .atomic(.equal("Animal.ObjectGuid", .string([=10=]))) })
        let predicate: GatewayRequestFactoryHelper.Predicate? = !predicates.isEmpty ? .or(predicates) : nil

        return gatewayConnector.fetchObjects(type: AnimalMilkSetting.self, predicate: predicate)
    }))
    .map {
        Array([=10=].joined())
    }
}

我认为这个解决方案比将结果包装在另一个 Promise 中要好。简单快捷。

PromiseKit 6.0 迁移

PromiseKit 6.0 migration

promise

ios

swift

promisekit