HttpRequestHeaderCollection.IfModifiedSince HttpRequestHeaderCollection.IfModifiedSince HttpRequestHeaderCollection.IfModifiedSince HttpRequestHeaderCollection.IfModifiedSince HttpRequestHeaderCollection.IfModifiedSince Property

Definition

Gets or sets the DateTime object that represents the value of an If-Modified-Since HTTP header on an HTTP request.

public : IReference<DateTime> IfModifiedSince { get; set; }
IReference<DateTime> IfModifiedSince();

void IfModifiedSince(IReference<DateTime> ifmodifiedsince);
public Nullable<DateTimeOffset> IfModifiedSince { get; set; }
Public ReadWrite Property IfModifiedSince As Nullable<DateTimeOffset>
var nullable = httpRequestHeaderCollection.ifModifiedSince;
httpRequestHeaderCollection.ifModifiedSince = nullable;

Property Value

Nullable<DateTimeOffset> Nullable<DateTimeOffset> Nullable<DateTimeOffset>

The DateTime object that represents the value of an If-Modified-Since HTTP header on an HTTP request. A null value means that the header is absent.

Remarks

The IfModifiedSince property represents the value of an If-Modified-Since HTTP header on an HTTP request message. The If-Modified-Since header is the date and time the content was modified since.

Javascript and .NET languages do not use the DateTime object directly. In Javascript a DateTime is projected as a object, and in .NET it is projected as a System.DateTimeOffset. Each language transparently handles the conversion to the granularity and date ranges for the respective language.

In C++, a value has the same granularity as a and supports the date ranges required by Javascript and .NET.

For more detailed information, see the Windows.Foundation.DateTime structure.

The following sample code shows a method to set the If-Modified-Since header on an HttpRequestMessage object using the IfModifiedSince property on the HttpRequestHeaderCollection object.

    public void DemonstrateHeaderRequestIfModifiedSince() {
        var request = new HttpRequestMessage();

        // This is not typically set with a string.

        // Set the header with a strong type.
        var value = DateTimeOffset.Now.AddDays(-1); // Since yesterday.
        request.Headers.IfModifiedSince = value;

        // Get the strong type out
        System.Diagnostics.Debug.WriteLine("IfModifiedSince value in ticks: {0}", request.Headers.IfModifiedSince.Value.Ticks);

        // The ToString() is useful for diagnostics, too.
        System.Diagnostics.Debug.WriteLine("The IfModifiedSince ToString() results: {0}", request.Headers.IfModifiedSince.ToString());
    }

See also