I was looking at the Redirect method in the SPUtility class.
Besides the url, this method also takes a parameter of type SPRedirectFlags. I
was wondering when to use the values of this enumeration. The MSDN documentation does help a bit, but
not very much. I asked on Twitter if anyone knew the meaning of
these values. Within minutes, Anders answered and pointed me in the
right direction. One of the examples of why I love Twitter!
The signature of the Redirect method is:
public static bool Redirect(string url, SPRedirectFlags flags, HttpContext context)
There is an overload
that also takes the queryString as a parameter. The SPRedirectFlags enumeration
has these values:
·
CheckUrl
·
Default
·
DoNotEncodeUrl
·
DoNotEndResponse
·
RelativeToLayoutsPage
·
RelativeToLocalizedLayoutsPage
·
Static
·
Trusted
·
UseSource
Source url
If UseSource is part of the flags parameter
of the Redirect method, the url to which the user is redirected will be read
from the querystring of the original request (context parameter). The new url
will be the value of one of these querystring parameters:
·
Source
·
NextUsing
·
NextPage
If one of these parameters has a value, the new url will be
validated. Validation is done by the IsUrlSafeForRedirect method of the Request
property of the current SPWeb. The url in the querystring of the original
request needs to be a relative url. See the samples below.
If this url is not valid, or the UseSource parameter resulted in
an empty string, the url parameter that was originally passed will be used.
Static url
If Static is part of the flags parameter,
the url is considered relative. Depending on the presence ofRelativeToLayoutsPage in
the flags parameter, the url is relative to the ´_layouts´. If
this enumeration value is present, SharePoint checks the flags parameter for
the presence of RelativeToLocalizedLayoutsPage. If this is present,
a new absolute url to the localized ‘_layouts’ folder is constructed. If not,
the url is constructed to the root of the ‘_layouts’ folder. The layouts url is
the url of the current SPWeb, followed by ‘_layouts’ and the Language of the
current SPWeb. If constructing this url fails for whatever reason, the url will
be the url of the current SPSite. If required, the value of
SPGlobal.ServerCulture.LCID is added to the url.
Absolute url
If Static is NOT part of the flags parameter,
the user will be redirected to the value of the url parameter,
after validating the url. If Trusted is part of the flags parameter,
the url is always valid. If Trusted is not available, it
depends on the outcome of the IsUrlSafeForRedirect method of the Request property
of the current SPWeb whether or not the url is valid.
Encoding
The last step is before the user is redirected is the encoding.
If DoNotEncodeUrl is NOT present in the flags attribute, the
url is first encoded using SPHttpUtility.UrlPathEncode.
Samples
Below you will find a number of samples. Each sample starts with
the sample code for SPUtility.Redirect. This code is tested in a web part. The
3 lines below that sample show the results of calling the redirect. The first
column contains the page url that contains the web part. The second column
contains the result of the redirect.
SPUtility.Redirect(http://newsite,
SPRedirectFlags.Default, HttpContext.Current);
|
no redirect
|
|
|
no redirect
|
|
|
no redirect
|
SPUtility.Redirect("/news", SPRedirectFlags.Default, HttpContext.Current);
SPUtility.Redirect(http://newsite,
SPRedirectFlags.Static, HttpContext.Current);
|
no redirect
|
|
SPUtility.Redirect(http://newsite,
SPRedirectFlags.UseSource, HttpContext.Current);
|
no redirect
|
|
|
no redirect
|
|
SPUtility.Redirect(http://newsite,
SPRedirectFlags.UseSource | SPRedirectFlags.Trusted, HttpContext.Current);
|
no redirect
|
|
SPUtility.Redirect(http://newsite,
SPRedirectFlags.Trusted, HttpContext.Current);
SPUtility.Redirect("settings.aspx", SPRedirectFlags.Static |
SPRedirectFlags.RelativeToLayoutsPage, HttpContext.Current);
SPUtility.Redirect("images/approve.gif", SPRedirectFlags.Static |
SPRedirectFlags.RelativeToLayoutsPage |
SPRedirectFlags.RelativeToLocalizedLayoutsPage, HttpContext.Current);
There are a few
members of the enumeration that I did not describe, because I was not able to
find out how these are used.
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