Why my script ignoring empty array result?

Question

I have a script that basically check if there is a result from a query:

$.post('<?php echo site_url('xxx/yyy'); ?>',{data:no},function(result){
        if(!result){
            alert("No Data");
        }
        else{
            alert("Data retrieved");
        }
});

Why my IF alert Data retrieved when I get empty JSON array. I tried to do alert(result) with different data (the data which result is empty and result is true), but both data is alerting Data retrieved.

This is my model:

$this->db->select('*',FALSE);
    $this->db->from('t_penomoran tp');      
    $this->db->join('t_penomoran_detail t_pd', 'tp.nomor = t_pd.nomor');

    $this->db->where('tp.nomor',$nomor);

    $query = $this->db->get();
    return $query->result_array();

note:
For some reason when I do alert(result.length) with data that has no value, the result is 2. But when I do alert(result) with data that has no value the result is []

Empty JSON array [] in stringified form is still string, so maybe you need to parse the result to actual JSON first? — Daniel H.J.
– Daniel H.J., Commented Oct 24, 2017 at 4:51
@DanielH.J. "JSON (JavaScript Object Notation) is a lightweight data-interchange format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others." - What is the difference between JSON and Object Literal Notation? — Andreas
– Andreas, Commented Oct 24, 2017 at 4:57
Andreas, what I am saying is the Ajax result is an empty JSON array that is stringified, so [] is not the same as '[]'. '[]' is a string with length of 2. You need to parse the result first. — Daniel H.J.
– Daniel H.J., Commented Oct 24, 2017 at 5:07
@DanielH.J. If the server doesn't send application/json as the content-type you're right. Otherwise jQuery will automatically parse the response (jsfiddle.net/Lpt9n8q3). — Andreas
– Andreas, Commented Oct 24, 2017 at 10:48

JohanP · Accepted Answer · 2017-10-24 04:51:28Z

1

Empty array is a truthy value, meaning in your if statement, it will evaluate to true and that is why you see the alert(). To fix it, use the length property:

if(!result.length) alert('no data')

answered Oct 24, 2017 at 4:51

JohanP

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2 Comments

ashura91 Over a year ago

still no luck. For some reason when I do alert(result.length) with data that has no value, the result is 2. But when I do alert(result) with data that has no value the result is []

James Over a year ago

That correlates to result being a string of length 2, namely”[]”

Jinesh · Accepted Answer · 2017-10-24 04:54:49Z

0

You can check like this

 if(jQuery.isEmptyObject(result))
{
        alert('no data')
}

answered Oct 24, 2017 at 4:54

Jinesh

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Comments

Asmarah · Accepted Answer · 2017-10-24 05:13:49Z

0

First of all parse your result like this

var res = result.responseJSON;

Then alert what you get if empty then it will be null. so you can filter that out

answered Oct 24, 2017 at 5:13

Asmarah

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