检查ajax返回的json数据是否已设置

In my application im getting the data from database using ajax call as json array data. But some times i may not get the data from database based on condition. How can i check whether there is any data in the ajax returned array.

Here is my code..

Ajax Call:

   $.ajax({ 
        type:'POST',
        url:'user_panel/index',
        data: 'ov_prem_home_id='+home_id,
        dataType: 'json',
        cache: false,
        success: function(dataResponse){
        document.getElementById('ov_prem_title').value=data[0]['title'];
        }
    });

PHP Code

        $home_id=$_POST[home_id];   
        $ov_result=getPremOveriewData($home_id);
        echo json_encode($ov_result);exit;

I tried the conditions like isset(dataResponse),if(dataResponse=='') but i didn't got anything

If what you want is to check the data from the Javascript end, you could use something like:

$.ajax({    
    type:'POST',
    url:'user_panel/index',
    data: 'ov_prem_home_id='+home_id,
    dataType: 'json',
    cache: false,
    success: function(dataResponse){
       if (data && dataResponse.length>0 && dataResponse[0]['title'])
       {
           document.getElementById('ov_prem_title').value=dataResponse[0]['title'];
       }
       else
       {
           //Empty
       }
    }
});

The simple way:

success: function(dataResponse){
   if(!dataResponse){ 
      // its empty
   }
}

And also you could insure yourself a bit more by doing this in PHP:

echo (empty($ov_result) ? null : json_encode($ov_result));exit;

This will return nothing (null) if $ov_result is empty

If the response is empty it will evaluate to false, so simply do if(dataResponse)

$.ajax({
    type:'POST',
    url:'user_panel/index',
    data: 'ov_prem_home_id='+home_id,
    dataType: 'json',
    cache: false,
    success: function(dataResponse){
        if (dataResponse) {
            document.getElementById('ov_prem_title').value=data[0]['title'];
        }
    }
});

$.ajax({    
    type:'POST',
    url:'user_panel/index',
    data: 'ov_prem_home_id='+home_id,
    dataType: 'json',
    cache: false,
    success: function(dataResponse){
    if(typeof dataResponse != 'undefined' && dataResponse.length > 0 )
      document.getElementById('ov_prem_title').value=data[0]['title'];
    }
});