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Paths in asp.net

When working with resources in a Web site, you must often specify a path for the resource. For example, you might use a URL path to reference an image file in a page or the URL of a page elsewhere in the Web site. Similarly, code in your Web application might use a physical file path to a server-based file to read or write the file.

Client Elements

Elements that are not server controls on a page are client elements. There are two ways for specifying a path in client elements.

A. Absolute path
An absolute URL path is useful if you are referencing resources in another location such as an external Web site.
For E.g. <img src="http://www.yourwebsite.com/MyApplication/Images/SampleImage.jpg" />

B. relative path
  • Site Root relative path
A site-root relative path, which is resolved against the site (not application) root. This example path assumes the existence of an Images folder under the Web site root:
For e.g <img src="/Images/SampleImage.jpg" /> for a website http://www.yourwebsite.com will be resolved as http://www.yourwebsite.com/Images/SampleImage.jpg
Site-root relative paths are useful if you keep cross-application resources such as images or client script files in a folder underneath the Web site root.

  • A relative path that is resolved against current page is <img src="Images/SampleImage.jpg" /> and against the peer of current page is <img src="../Images/SampleImage.jpg" />
Note By default, browsers resolve relative paths using the current page URL as the base. However, you can include an HTML base element in a page to specify an alternate base path.


Server Controls.

If you use relative paths, they are resolved relative to the path of the page, user control, or theme in which the control is contained.

For example, imagine that you have a user control in a Controls folder. The user control contains an Image Web server control whose ImageUrl property is set to the following path:

Images/SampleImage.jpg

When the user control runs, the path will resolve to the following:

/Controls/Images/SampleImage.jpg

This is true even no matter where the page is that hosts the user control.

Absolute and relative path references in a server control have the following disadvantages:

Absolute paths are not portable between applications. If you move the application that the absolute path points to, the links will break.

Relative paths in the style of client elements can be difficult to maintain if you move resources or pages to different folders.

To overcome these disadvantages, ASP.NET makes available the Web application root operator (~), which you can use when specifying a path in server controls. ASP.NET resolves the ~ operator to the root of the current application. You can use the ~ operator in conjunction with folders to specify a path that is based on the current root. The following examples show the ~ operator used to specify root-relative paths for an image when using the Image server control:


<asp:image runat="server" id="Image1"
ImageUrl="~/Images/SampleImage.jpg" />

Note: The ~ operator is recognized only for server controls and in server code. You cannot use the ~ operator for client elements.

In master pages, paths to resources are resolved based on the path of the content page.

DebugGuru

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