[LON-CAPA-users] Disabling remote browser caching answers?

[Stuart Raeburn]

Hi Ray,

>   What, if any, is the best way for an author or course coordinator   
> to prevent students' browsers caching answers in a problem?

I doubt this is a caching issue.

When rendering a problem the response header sent to the browser by  
LON-CAPA includes:

Pragma: no-cache
Cache-Control: no-cache
Expires: <current date/time>

However, if the problem is being displayed after a student has made  
prior submissions, and the status is CAN_ANSWER then the most recent  
submission will be displayed in the textbox where the student enters  
an answer.

Some possibilities which could be implemented currently:

(a) Set the question type for the problem to "New Randomization Each N  
Tries (default N=1)"

or

(b) Add a javascript function to be called on page load to set the  
value attribute for all <input> form elements with name or id  
beginning with the string: HWVAL_ to ''.

Other possibilities, which would require modifications to LON-CAPA,  
would be to optionally exclude $oldresponse from the value attribute  
on the server side when the content is being rendered, and also to add  
a javascript function, as outlined in (b), to LON-CAPA itself, and  
then provide a parameter, settable by the CC, to determine whether to  
exclude $oldresponse and also run the javascript function on page load.


Stuart Raeburn
LON-CAPA Academic Consortium


Quoting Raymond Batchelor <batchelo at sfu.ca>:

> Hi All,
>   What, if any, is the best way for an author or course coordinator   
> to prevent students' browsers caching answers in a problem?
>
> --
> Ray
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