ASP Razor: displaying current data from database

Question

I need to display currently stored data on website which refreshes itself automatically only if the data changed.

My current approach which failed:

request data from database let's say every 10s
check if this data differs from the currently displayed one

What I did:

setInterval(function() {refreshData()}, 5000);

function refreshData() {
        @{
            var db2 = Database.Open("StarterSite");    
            string tresc2 = db.QuerySingle(someQuery, 3).Tresc;


            <text>
                alert(@tresc2);
            </text>


        }        
    }

the problem here is that this code seems to be working fine, I do not get any error messages but @tresc2 does not exist. It looks like db2 also does not exist.

I do not understand what is going on here.

Two questions if I may:

what should be a proper approach to my problem?
what do I do wrong here?

Thank you

alert needs quotes around the argument.

mxmissile
– mxmissile

2014-05-01 20:37:26 +00:00
Commented May 1, 2014 at 20:37 — mxmissile
– mxmissile, Commented May 1, 2014 at 20:37

Wiktor Zychla · Accepted Answer · 2014-05-01 21:03:30Z

1

The code at the server side gets executed and when it renders, it becomes

setInterval(function() {refreshData()}, 5000);

function refreshData() {
    alert(somevalue);
}

What you get then is that you constantly call the very same function that alerts the very same message.

A more correct approach would be to ajax-call the server and update the page:

<div id="divToRefresh" />
<script type="text/ecmascript">

   $(function() {
     setInterval(function() {refreshData()}, 5000);

     function refreshData() {
       $.ajax( {
         url : 'controller/action',
         async : false,
         success: function(data) {
           $("#divToRefresh").html(data);
        }
     }
  });
</script>

This assumes that the controller/action controller/action returns a partial html that contains a refreshed fragment of your page.

answered May 1, 2014 at 21:03

Wiktor Zychla

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3 Comments

Jacek Wojcik Over a year ago

Thank you for your answer. Do not know much about AJAX and I need to have my problem solved ASAP so if possible: could you please tell me where in the ajax function you mentioned should I add my request to the database (I should probably mention that my web page is not MVC).

Wiktor Zychla Over a year ago

@JacekWojcik: the call to the database is done at the server side. The url of the ajax call can point to anythhing, mvc, webforms, whatever.

Jacek Wojcik Over a year ago

To force browser to display new data it is also necessary to set cache = false as a parameter for $.ajax method.

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