Question

我有两个模型，它们有一对多的关系。这是我的课程。

预订

final class Booking: PostgreSQLModel {
    /// The unique identifier for this `Todo`.
    var id: Int?

    /// A title describing what this `Todo` entails.
    var user_id: User.ID
    var product_id: Product.ID
    var count: Int

    /// Creates a new `Todo`.
    init(id: Int? = nil, user_id: User.ID, product_id: Product.ID, count: Int) {
        self.id = id
        self.user_id = user_id
        self.product_id = product_id
        self.count = count
    }
}
extension Booking {
    var user: Parent<Booking, User> {
        return parent(\.user_id)
    }
    var product: Parent<Booking, Product> {
        return parent(\.product_id)
    }
}

产品

final class Product: PostgreSQLModel {
    /// The unique identifier for this `Todo`.
    var id: Int?

    /// A title describing what this `Todo` entails.
    var name: String
    var image_url: String
    var description: String
    var price: Int?

    /// Creates a new `Todo`.
    init(id: Int? = nil, name: String, image_url: String, description: String, price: Int) {
        self.id = id
        self.name = name
        self.image_url = image_url
        self.description = description
        self.price = price
    }
}
extension Product {
    var bookings: Children<Product, Booking> {
        return children(\.product_id)
    }
}

现在，我想获取用户的所有预订，并且每次预订时我也要获取产品信息。因此，为此，我尝试连接Booking和Product表，但这会引发异常。

致命错误：“尝试！”表达式意外引发错误：⚠️CoreError：Parent<Booking, Product>不符合ReflectionDecodable。 -id：CoreError.ReflectionDecodable ：文件/BuildRoot/Library/Caches/com.apple.xbs/Sources/swiftlang_Fall2018/swiftlang_Fall2018-1000.11.42/src/swift/stdlib/public/core/ErrorType.swift，第184行程序以退出代码结束：9

这是我的加入代码。

let booking = Booking.query(on: req).join(\Product.bookings, to:\Booking.product).filter(\.user_id == userID).decode(BookingM.self).all()

Answer 1

首先，使用您所拥有的查询，您无需加入- (void) zoomPinchGestureRecognizerAction: (UIPinchGestureRecognizer *) sender { static CGFloat initialVideoZoomFactor = 0; NSLog(@"Pinch Zoom Activated!"); // Find the current capture device. AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithDeviceType: AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType: AVMediaTypeVideo position: self.defaultAVCaptureDevicePosition]; if (sender.state == UIGestureRecognizerStateBegan) { initialVideoZoomFactor = captureDevice.videoZoomFactor; } else { CGFloat scale = MIN(MAX(1, initialVideoZoomFactor * sender.scale), 4); [CATransaction begin]; [CATransaction setAnimationDuration: 0.01]; customPreviewLayer.affineTransform = CGAffineTransformMakeScale(scale, scale); [CATransaction commit]; if ([captureDevice lockForConfiguration: nil] == YES) { captureDevice.videoZoomFactor = scale; [captureDevice unlockForConfiguration]; } } }表，因为您无需对其进行查询或解码。

您的Product语句：

join

不正确。您应该加入.join(\Product.bookings, to:\Booking.product)属性，而不是加入Product.bookings属性，因为产品的ID是Product.id属性包含的内容。

因此，您的Fluent查询应如下所示：

Booking.product

我删除了let booking = Booking.query(on: req).join(\Booking.product, to:\Product.id).filter(\.user_id == userID).all()调用，因为查询也已经.decoding解码了查询结果。

要使用您的Booking属性，您的查询应如下所示：

bookings

与蒸气流利加入时崩溃

1 个答案: