When developing a web project, we often encounter a situation where the data in the database does not exist or is deleted, and the corresponding web page does not exist/error. So how should we deal with this situation?
Generally, similar code: Product pro = GetProduct (123); returns the Product information numbered 123. If you do not judge pro = null, you can directly reference the property of pro, the NullReferenceException (to reference an object to an object instance) is thrown. set in config
Will go to the Progress page, but the jump to err. aspx is the 302 status code returned. In fact, because the product does not exist, we need to return the status code 404. The Status Code 404 is not only for the user, but for the user, it does not matter, however, the search engine will see this status code. If a large number of products do not exist, this will lead to the existence of the product information previously indexed by the search engine, the actual content is not found, which will reduce the search engine's trust in the website. See my practices below:
Create 404. aspx in the root directory of the website. The background code is as follows:
Protectedvoid Page_Load (object sender, EventArgs e)
The front-end code is as follows:
<% @ Page Language = "C #" AutoEventWireup = "true" CodeBehind = "404. aspx. cs" Inherits = "Web. _ 04" %>
<! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Transitional // EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<Html xmlns = "http://www.w3.org/1999/xhtml">
<Head runat = "server">
<Title> the page you accessed does not exist </title>
</Head>
<Body>
<Form id = "form1" runat = "server">
<Div>
<H1> the page you visit does not exist (will automatically jump to the <a href = "http://www.svnhost.cn"> Home page </a>)
<Script language = "javascript">
Function go ()
{
Window. location = "http://www.svnhost.cn ";
}
SetTimeout (go, 3000 );
</Script>
</Div>
</Form>
</Body>
</Html>
Now we have a 404 page.
Next we will call this page:
Product pro = GetProduct (123 );
If (pro = null) Server. Transfer ("/404. aspx ");
After deleting a product, the search engine crawls the page and returns the 404 status code. Then, the index is deleted.
If the website has a similar problem, you can view it in the Google website administrator tool.
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