如何在Django REST框架mixin中引用子类？

问题描述

在Django Rest Framework中，我试图为视图集中的以下两个方法编写一个mixin：

class OrderViewSet(viewsets.ModelViewSet):
    # ...
    def get_object(self):
        pk = self.kwargs.get('pk')

        if pk == 'me':
            user = self.request.user
            return get_object_or_404(Order,user=user.pk)

        return super(OrderViewSet,self).get_object()

    def get_queryset(self):
        user = self.request.user
        return Agent.objects.filter(user=user)

除了super(OrderViewSet,self)之外，这似乎很简单，因为在声明它们之前，我需要以某种方式在我的mixin类中引用不同的视图集类。有提示吗？

解决方法

使用新样式的super（）调用

class DefaultFileRepository {
    
    // MARK: Properties
    
    let queue: DispatchQueue = .global()
    let fileManager: FileManager = .default
    lazy var baseURL: URL = {
        try! fileManager
            .url(for: .libraryDirectory,in: .userDomainMask,appropriateFor: nil,create: true)
            .appendingPathComponent("MyFiles")
    }()
    
    
    // MARK: Private functions
    
    private func doRead(from path: String) throws -> String {
        let url = baseURL.appendingPathComponent(path)
        
        var isDir: ObjCBool = false
        guard fileManager.fileExists(atPath: url.path,isDirectory: &isDir) && !isDir.boolValue else {
            throw ReadWriteError.doesNotExist
        }
        
        let string: String
        do {
            string = try String(contentsOf: url)
        } catch {
            throw ReadWriteError.readFailed(error)
        }
        
        return string
    }
    
    private func doWrite(_ string: String,to path: String) throws {
        let url = baseURL.appendingPathComponent(path)
        let folderURL = url.deletingLastPathComponent()
        
        var isFolderDir: ObjCBool = false
        if fileManager.fileExists(atPath: folderURL.path,isDirectory: &isFolderDir) {
            if !isFolderDir.boolValue {
                throw ReadWriteError.canNotCreateFolder
            }
        } else {
            do {
                try fileManager.createDirectory(at: folderURL,withIntermediateDirectories: true)
            } catch {
                throw ReadWriteError.canNotCreateFolder
            }
        }
        
        var isDir: ObjCBool = false
        guard !fileManager.fileExists(atPath: url.path,isDirectory: &isDir) || !isDir.boolValue else {
            throw ReadWriteError.canNotCreateFile
        }
        
        guard let data = string.data(using: .utf8) else {
            throw ReadWriteError.encodingFailed
        }
        
        do {
            try data.write(to: url)
        } catch {
            throw ReadWriteError.writeFailed(error)
        }
    }
    
}


extension DefaultFileRepository: FileRepository {
    func read(from path: String) throws -> String {
        try queue.sync { try self.doRead(from: path) }
    }
    
    func readAsync(from path: String,completion: @escaping (Result<String,Error>) -> Void) {
        queue.async {
            do {
                let result = try self.doRead(from: path)
                completion(.success(result))
            } catch {
                completion(.failure(error))
            }
        }
    }
    
    func write(_ string: String,to path: String) throws {
        try queue.sync { try self.doWrite(string,to: path) }
    }
    
    func writeAsync(_ string: String,to path: String,completion: @escaping (Result<Void,Error>) -> Void) {
        queue.async {
            do {
                try self.doWrite(string,to: path)
                completion(.success(Void()))
            } catch {
                completion(.failure(error))
            }
        }
    }
    
}


enum ReadWriteError: LocalizedError {
    
    // MARK: Cases
    
    case doesNotExist
    case readFailed(Error)
    case canNotCreateFolder
    case canNotCreateFile
    case encodingFailed
    case writeFailed(Error)
}