Need to create Json object in php

Question

I want to create a json object using php like below as I need to create a stacked bar chart using d3.js, hence I am using data from oracle table and need the json data as above image.
My table has these 3 columns. (ID, NAME, Layers) like:-

ID, NAME, Layers
1   ABC   a:8,b:10
2   WWW   c:8,d:7

When I am fetching data from oracle, my php code is:-

while (($row = oci_fetch_array($stid, OCI_ASSOC))) {
          $streamArr[] = $row;
}    
header("Access-Control-Allow-Origin: *");
echo json_encode($streamArr);

I am getting this error:-

Warning: [json] (php_json_encode) type is unsupported, encoded as null in line 48
json output as:-
[["1","ABC",{"descriptor":null}],["2","WWW",{"descriptor":null}]]

can you please help me in rectifying with this issue?

Images and screenshots can be a nice addition to a post, but please make sure the post is still clear and useful without them. Don't post images of code or error messages. Read why Instead copy and paste or type the actual data into the post directly. — Filnor
– Filnor, Commented Dec 13, 2017 at 8:37

marekful · Accepted Answer · 2017-12-13 08:46:52Z

1

The error message refers to a field you didn't mention in the example. Maybe just don't select unneeded fields?

If you fix that, you still won't get the desired JSON structure. To get layers as an object in every element of data in the resulting JSON, you need to convert the string values stored in the database to PHP arrays before encoding.

You could do that with similar code:

while (($row = oci_fetch_array($stid, OCI_ASSOC))) 
{
  $row['layers'] = array_map(function($el) {
    return explode(':', $el);
  }, explode(',', $row['layers']));

  $streamArr[] = $row;
}

answered Dec 13, 2017 at 8:46

marekful

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1 Comment

Camille Over a year ago

Nice solution! Bravo!

Camille · Accepted Answer · 2017-12-13 09:41:37Z

1

@marekful answer is really nice, not easiest to understand but efficient and short!

Here you have a longer and not so efficient, but maybe easier to get.

$streamArr = array();
while (($row = oci_fetch_array($stid, OCI_ASSOC))) 
{
    // Get ID and NAME
    $data = array(
        'id' => $row['ID'],
        'name' => $row['NAME'],
        'layers' => array()
    );
    // Get Layers by split by comma
    $layers = explode(',', $row['layers']);
    foreach ($layers as $layer) {
        // Get layer parts by slit with double-point
        $layersPart = explode(':', $layer);
        foreach ($layersPart as $key => $value) {
            $data['layers'][$key] = $value;
        }
    }
    // Add to global array
    $streamArr[] = $data;
}
echo json_encode($streamArr);

answered Dec 13, 2017 at 9:41

Camille

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1 Comment

marekful Over a year ago

Thanks Camille, your solution is indeed more readable but quite a bit longer. You will want to be short when you work a lot with code, plus it becomes easier to read, too. explode does its own "foreach" internally though, but it uses a tokeniser on the string and iterates over the tokens to create an array. These kind of PHP functions are handy to hide complexity.

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