WindowsAzure.Storage v2 StorageException

问题:

I'm migrating from WindowsAzure.StorageClient 1.7 to WindowsAzure.Storage 2.0, and I'm working right now on the management of the exceptions. Following this guide and other sources, I found out I had to migrate from

try
{
    // Something
}
catch (StorageClientException e)
{
    switch (e.ErrorCode)
    {
        case StorageErrorCode.ContainerNotFound:
        case StorageErrorCode.ResourceNotFound:
        case StorageErrorCode.BlobNotFound:
        case StorageErrorCode.ConditionFailed:
            // Do something
    }
}

to

try
{
    // Something
}
catch (StorageException e)
{
    switch (e.RequestInformation.ExtendedErrorInformation.ErrorCode)
    {
        case StorageErrorCodeStrings.ContainerNotFound:
        case StorageErrorCodeStrings.ResourceNotFound:
        case BlobErrorCodeStrings.BlobNotFound:
        case StorageErrorCodeStrings.ConditionNotMet:
            // Do something
    }
}

Looks simple. The problem is ExtendedErrorInformation is always equal to null. The HttpStatusMessage instead says 'The specified blob does not exist.', as it should.

I thought it was caused by the simulator of the test environment, but trying it in a real Azure environment drived me to the same situation.

Any idea?

回答1:

Another option is to look at the RequestInformation.HttpStatusCode instead. This seems to be more reliable anyway. Your code translates rather easily to:

try
{
    // Something
}
catch (StorageException e)
{
    switch (e.RequestInformation.HttpStatusCode)
    {
        case (int)HttpStatusCode.NotFound:
        case (int)HttpStatusCode.PreconditionFailed:
        // Do something
    }
}

回答2:

I just tried it and was surprised to see that indeed the ExtendedErrorInformation object is null. However it's not always null. For example, if I try to create a blob container which already exists using blobContainer.Create() method, I will get a non-null ExtendedErrorInformation. However if I try and fetch attributes of a blob which does not exist in the blob container, I will get a null ExtendedErrorInformation object. I guess one can't just assume that ExtendedErrorInformation object will always be available.

Also I noticed that in your code for 2.0, you're using StorageErrorCodeStrings. Please note that it is removed from 2.0 and is available only available with version 1.8 or before. Thought I should mention that

Update: Please see comment below from @VollmonD. This has been added in version 2.0.3.

回答3:

Late to the party, but if you are trying to handle deleting items from the blob or just checking if they exist (extension method kinda approach). you can now use:

• CloudBlob.DeleteIfExistsAsync() - https://msdn.microsoft.com/en-us/library/microsoft.windowsazure.storage.blob.cloudblockblob.deleteifexistsasync.aspx

• CloudBlob.ExistsAsync() - https://msdn.microsoft.com/en-us/library/mt423366.aspx

Check here for a list of methods on CloudBlob: https://msdn.microsoft.com/en-us/library/microsoft.windowsazure.storage.blob.cloudblockblob.aspx