如何在模型类定义中访问Django模型属性？

Question

此代码的问题是，当我尝试访问function randomVersion { Get-Random -InputObject '1', 'test', '14.1.3.5397', '14.2.3.5399', '15.4.2.1327', '15.5.2.1328', '16.3.7.9437', '16.7.7.9438' } Import-Module -Name Pester Describe "Tests for randomVersion" { It "works" { $result = randomVersion $version = $result -as [version] $version | Should -not -BeNullOrEmpty if ($version) { $version.Major | Should -BeIn 14, 15, 16 } } } 时，我得到了

    java.nio.file.FileSystemException: C:\Workspace\kafka_2.11-1.1.0\kafka-logs\discrete-topic-0\00000000000000000000.log -> C:\Workspace\kafka_2.11-1.1.0\kafka-logs\discrete-topic-0\00000000000000000000.log.deleted: The process cannot access the file because it is being used by another process.

        at sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:86)
        at sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:97)
        at sun.nio.fs.WindowsFileCopy.move(WindowsFileCopy.java:387)
        at sun.nio.fs.WindowsFileSystemProvider.move(WindowsFileSystemProvider.java:287)
        at java.nio.file.Files.move(Files.java:1395)
        at org.apache.kafka.common.utils.Utils.atomicMoveWithFallback(Utils.java:697)
        at org.apache.kafka.common.record.FileRecords.renameTo(FileRecords.java:212)
        at kafka.log.LogSegment.changeFileSuffixes(LogSegment.scala:415)
        at kafka.log.Log.kafka$log$Log$$asyncDeleteSegment(Log.scala:1601)
        at kafka.log.Log.kafka$log$Log$$deleteSegment(Log.scala:1588)
        at kafka.log.Log$$anonfun$deleteSegments$1$$anonfun$apply$mcI$sp$1.apply(Log.scala:1170)
        at kafka.log.Log$$anonfun$deleteSegments$1$$anonfun$apply$mcI$sp$1.apply(Log.scala:1170)
        at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
        at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
        at kafka.log.Log$$anonfun$deleteSegments$1.apply$mcI$sp(Log.scala:1170)
        at kafka.log.Log$$anonfun$deleteSegments$1.apply(Log.scala:1161)
        at kafka.log.Log$$anonfun$deleteSegments$1.apply(Log.scala:1161)
        at kafka.log.Log.maybeHandleIOException(Log.scala:1678)
        at kafka.log.Log.deleteSegments(Log.scala:1161)
        at kafka.log.Log.deleteOldSegments(Log.scala:1156)
        at kafka.log.Log.deleteRetentionMsBreachedSegments(Log.scala:1228)
        at kafka.log.Log.deleteOldSegments(Log.scala:1222)
        at kafka.log.LogManager$$anonfun$cleanupLogs$3.apply(LogManager.scala:854)
        at kafka.log.LogManager$$anonfun$cleanupLogs$3.apply(LogManager.scala:852)
        at scala.collection.TraversableLike$WithFilter$$anonfun$foreach$1.apply(TraversableLike.scala:733)
        at scala.collection.immutable.List.foreach(List.scala:392)
        at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:732)
        at kafka.log.LogManager.cleanupLogs(LogManager.scala:852)
        at kafka.log.LogManager$$anonfun$startup$1.apply$mcV$sp(LogManager.scala:385)
        at kafka.utils.KafkaScheduler$$anonfun$1.apply$mcV$sp(KafkaScheduler.scala:110)
        at kafka.utils.CoreUtils$$anon$1.run(CoreUtils.scala:62)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:748)
        Suppressed: java.nio.file.FileSystemException: C:\Workspace\kafka_2.11-1.1.0\kafka-logs\discrete-topic-0\00000000000000000000.log -> C:\Workspace\kafka_2.11-1.1.0\kafka-logs\discrete-topic-0\00000000000000000000.log.deleted: The process cannot access the file because it is being used by another process.

                at sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:86)
                at sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:97)
                at sun.nio.fs.WindowsFileCopy.move(WindowsFileCopy.java:301)
                at sun.nio.fs.WindowsFileSystemProvider.move(WindowsFileSystemProvider.java:287)
                at java.nio.file.Files.move(Files.java:1395)
                at org.apache.kafka.common.utils.Utils.atomicMoveWithFallback(Utils.java:694)
                ... 32 more

And then...

[2018-08-01 18:14:01,479] INFO [ReplicaManager broker=0] Stopping serving replicas in dir C:\Workspace\kafka_2.11-1.1.0\kafka-logs (kafka.server.ReplicaManager)
[2018-08-01 18:14:01,480] ERROR Uncaught exception in scheduled task 'kafka-log-retention' (kafka.utils.KafkaScheduler)
org.apache.kafka.common.errors.KafkaStorageException: Error while deleting segments for discrete-topic-0 in dir C:\Workspace\kafka_2.11-1.1.0\kafka-logs
Caused by: java.nio.file.FileSystemException: C:\Workspace\kafka_2.11-1.1.0\kafka-logs\discrete-topic-0\00000000000000000000.log -> C:\Workspace\kafka_2.11-1.1.0\kafka-logs\discrete-topic-0\00000000000000000000.log.deleted: The process cannot access the file because it is being used by another process.
[2018-08-01 18:14:01,504] INFO Stopping serving logs in dir C:\Workspace\kafka_2.11-1.1.0\kafka-logs (kafka.log.LogManager)
[2018-08-01 18:14:01,508] ERROR Shutdown broker because all log dirs in C:\Workspace\kafka_2.11-1.1.0\kafka-logs have failed (kafka.log.LogManager)

username属性是从Django的AbstractUser继承的。

我进行了一些谷歌搜索，发现为了使自变量存在，我需要创建一个init方法。问题是我不想在init中做任何事情，因为我的Django代码的其余部分已经处理了实例化，并且我的应用程序按原样工作。我尝试使用“ pass”创建一个init方法，但这也给了我同样的错误。

有什么方法可以访问我的属性，而无需认真更改模型或进行新的迁移？我在Windows 10操作系统上使用Django 2.0。

Answer 1

只需避免在upload_to上串接字符串路径，然后将您的方法移出类

def profile_pic_path(instance, filename):
    return 'users/{0}/{1}'.format(instance.username, filename)

class Profile(models.Model):
    #other fields
    profile_picture = models.FileField(upload_to=profile_pic_path)

Answer 2

您可以在upload_to的{​​{1}}参数中使用可调用对象。参见documentation。

models.Imagefield