[This topic is part of the Microsoft Azure Storage Client Library 1.7, which has been deprecated. See Storage Client Library for the latest version.]
Returns an access condition such that an operation will be performed only if the resource has been modified since the specified time. Namespace: Microsoft.WindowsAzure.StorageClient
Assembly: Microsoft.WindowsAzure.StorageClient (in Microsoft.WindowsAzure.StorageClient.dll)
Returns an access condition such that an operation will be performed only if the resource has been modified since the specified time. Namespace: Microsoft.WindowsAzure.StorageClient
Assembly: Microsoft.WindowsAzure.StorageClient (in Microsoft.WindowsAzure.StorageClient.dll)
Usage
| Visual Basic |
|---|
Dim lastModifiedUtc As DateTime Dim returnValue As AccessCondition returnValue = AccessCondition.IfModifiedSince(lastModifiedUtc) |
Syntax
| Visual Basic |
|---|
Public Shared Function IfModifiedSince ( _ lastModifiedUtc As DateTime _ ) As AccessCondition |
| C# |
|---|
public static AccessCondition IfModifiedSince ( DateTime lastModifiedUtc ) |
| C++ |
|---|
public: static AccessCondition IfModifiedSince ( DateTime lastModifiedUtc ) |
| J# |
|---|
| JScript |
|---|
Parameters
- lastModifiedUtc
The last-modified time for the resource, expressed as a UTC value.
Return Value
A structure specifying the If-Modified-Since condition.Example
The following code example checks an access condition on the source blob and copies the blob if the condition is met.
| C# | Copy Code |
|---|---|
static void CopyIfModifiedSince(Uri blobEndpoint, string accountName, string accountKey)
{
//Create service client for credentialed access to the Blob service.
CloudBlobClient blobClient = new CloudBlobClient(blobEndpoint, new StorageCredentialsAccountAndKey(accountName, accountKey));
//Get a reference to the source blob.
CloudBlob sourceBlob = blobClient.GetBlobReference("mycontainer/myblob.txt");
sourceBlob.FetchAttributes();
//Get a reference to the destination blob.
CloudBlob destBlob = blobClient.GetBlobReference("mycontainer/copy-if-modified-since.txt");
BlobRequestOptions options = new BlobRequestOptions();
DateTime dt = new DateTime(2010, 9, 1, 0, 0, 0, DateTimeKind.Utc);
try
{
//Copy the source blob to the destination blob if the source blob has been modified since 9/1/2010.
options.CopySourceAccessCondition = AccessCondition.IfModifiedSince(dt.ToUniversalTime());
destBlob.CopyFromBlob(sourceBlob, options);
}
catch (StorageClientException e)
{
if (e.StatusCode == HttpStatusCode.PreconditionFailed)
{
Console.WriteLine("Access condition not met - blob " + sourceBlob.Uri + " has not been modified since " + dt.ToUniversalTime());
}
else
{
Console.WriteLine("Error code: " + e.ErrorCode);
}
}
}
| |
Remarks
Setting this access condition modifies the request to include the HTTP If-Modified-Since conditional header.
If this access condition is set, the operation is performed only if the resource has been modified since the specified time.
See Specifying Conditional Headers for Blob Service Operations for more information.
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.