Determine how an ASP.NET Web page was invoked

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Determine how an ASP.NET Web page was invoked

Examine the values of the following Page class properties, and then refer the table to determine how the page was invoked:

  • IsPostBack

  • PreviousPage

  • IsCrossPagePostBack

  • IsCallback

The following table lists ways in which a page can be invoked and the corresponding Page property values.

Invocation method

Property values

Original request

  • IsPostBack is set to false.

  • PreviousPage is set to null (Nothing in Visual Basic).

  • IsCallback is set to false.

Postback

  • IsPostBack is set to true.

  • PreviousPage is set to null (Nothing in Visual Basic).

  • IsCallback is set to false.

Cross-page posting

  • IsPostBack is set to false.

  • PreviousPage references the source page.

  • IsCrossPagePostBack is set to true.

  • IsCallback is set to false.

Server transfer

  • IsPostBack is set to false.

  • PreviousPage references the source page.

  • IsCrossPagePostBack that is referenced in the PreviousPage is set to false.

  • IsCallback is set to false.

Callback

  • IsPostBack is set to false.

  • PreviousPage is set to null (Nothing in Visual Basic).

  • IsCallback is set to true.
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2 thoughts on “Determine how an ASP.NET Web page was invoked”

  1. It is often useful to know how an ASP.NET Website was invoked: whether by an unique ask for (an HTTP GET), a postback (an HTTP POST), a cross-page publish from another web page (an HTTP POST), or a exchange from another web page using the Transfer technique or using a callback from the web browser.

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