jQuery Ajax Json response - check if is null - php

Question

I am getting data from MySQL using jQuery Ajax and JSON. However I need to know when the response is empty. I passe a date parameter to my php that will return some data or not... depending on date.
My Javascript code (simple version):
function pac_irra(date){
.ajax({
url: 'get_db_data/pac_irra.php?date='+date,
dataType: 'JSON',
type: 'POST',
data: {get_values: true},
beforeSend: function(){
$("#morris-line-chart").append(load_img);
},
success: function(response) {
date = response[0].Timestamp;
$('#a1').append(date);
},
});
}
If for example I used yesterday (2015-09-26) data I get the following json data (only a part of it):
[{"Timestamp":"2015-09-26 16:50:00","pac":"35.20","irra":"38.97"},{"Timestamp":"2015-09-26 17:00:00","pac":"32.19","irra":"35.51"}]
Now, for example, if I chose a date without data it returns:
[]
In my javascript code below I would like to add a if statement to my success function in case of json array is empty... something like:
function pac_irra(date){
.ajax({
url: 'get_db_data/pac_irra.php?date='+date,
dataType: 'JSON',
type: 'POST',
data: {get_values: true},
beforeSend: function(){
$("#morris-line-chart").append(load_img);
},
success: function(response) {
date = response[0].Timestamp;
$('#a1').append(date);
if ( ***array is empty***) {
('#a1').append('No data');
};
},
});
}
In my success function I have a morris chart created with the json data... I don't put it in the code...
So how do I check if it's empty? I already made a lot of attempts:
if (response.length == 0)
or another attempt
if (response[0].Timestamp == "") or if (!response)
And nothing works... I still can't check if the json array is empty...
My php code:
<?php
error_reporting(0);
$path = $_SERVER['DOCUMENT_ROOT'];
$path .= "/database/db_connect.php";
include_once($path);
if(isset($_GET['date'])) {
$date = $_GET['date'];
$days = $_GET['days'];
$var = array();
$query = "SELECT CONVERT_TZ(CONCAT(Date,' ',pac.Time), 'UTC', 'Europe/Lisbon' ) as Timestamp, ROUND((pac.Value/6440)*100,2) pac, ROUND((irra.Value/1000)*100,2) irra
FROM AggData pac
LEFT JOIN (SELECT Time, Value
FROM AggData WHERE Date=DATE_ADD('$date',INTERVAL '$days' DAY) and idEquipment=5 and idMeasure=6 ) irra
ON pac.Time=irra.Time
Where pac.Date=DATE_ADD('$date',INTERVAL '$days' DAY) and pac.idEquipment=1 and pac.idMeasure=3
AND (irra.Value>0 or pac.Value>0)
Order BY pac.Time asc
" or die("Error in the consult.." . mysqli_error($link));
$result = $link->query($query);
while($obj = mysqli_fetch_object($result)) {
$var[] = $obj;
}
echo json_encode($var);
}
?>

Answer 1

Try below if will check various condition
if((response && jQuery.isArray(response))?(response.length==0?false:(jQuery.isPlainObject(response[0])?!jQuery.isEmptyObject(response[0]):response[0])):response){
//console.log("adfdsaf");
}
if it will check if
response is null or undefined
or response == []
or response == [{}] or response[""]
I think this is the problem
success: function(response) {
if((response && jQuery.isArray(response))?(response.length==0?false:(jQuery.isPlainObject(response[0])?!jQuery.isEmptyObject(response[0]):response[0])):response){
('#a1').append('No data');
}else{
date = response[0].Timestamp;
$('#a1').append(date);
}
};
},
hopefully it will work