View state FAQ's

 Updated on October 07, 2014     VIKRAM     1225

Q: What is View state?

Ans: A View state is a hidden element which contains the data of all the controls present on a page in a encrypted manner.

  • View state is loaded after Page_Init.
  • View state is created after Page_PreRender.

Q: What type of data can be stored in View state variable?

Ans: Any type of data can be stored, but reference type of information needs serialization and deserialization.

Q: How much amount of data can be maintained by using View state variable?

Ans: No limit, but more information is not preferred.

Q: How the View state information can be carried between client and server?

Ans: By using Hidden controls along with request and response.

Q: What is the security protocol used to encrypt View state information?

Ans: Base64 algorithm

Q: What is the meaning of "EnableViewStateMac = true" in page directive?

Ans: It is indication to runtime environment to verify the required security algorithm used for encryption and decryption of viewstate information in machine.config file, instead of using default security algorithm i.e Base64.

Q: What is the StateBag object?

Ans:

  • It will hold complete state information of serverside controls, it is created based on the data taken from Hideden control with id __ViewState
  • SateBag object is usefull while processing page as well as while rendering page. So that automatic View state can be maintained for server side controls

Q: What is the Hidden control?

Ans: It is like textbox control, which is used to maintain state of server side control.

Q: Where the memory for View state variable is allocated?

Ans: No memory is reserved either at client or at server, data will be transmitted along with request and response in the form of hidden controls.

Q: What are the disadvantages of Viewstate?

Ans:

  1. Extra information need to be transmitted for each request and response
  2. Data will be unsecured, since base64 algorithm is known to all

Q: At what level automatic View state can be controlled?

Ans: Automatic View state can be controlled in three levels

1). At control level:

ex:<input type="text" enableviestate="true" id="txt1" runat="server"/>

2). At page level:

goto page directive 

<% @page language="cs" enableviewstate="true" %>

3). At Application level:

goto web.config

<system.Web>
   <pages enableviewstate="true">
   </pages>
</system.Web>

Q: Is it posssible to maintain automatic View state for password fields?

Ans: No, by default automatic View state is disabled for password fields.

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