PHP - Inserting into and getting from XML file

Question

I've written the following, using JSON, for a chat system:

header('Content-type: application/json');

$theName = $_GET['name'];
$theMessage = $_GET['message'];

$str = file_get_contents("transactions.json");

if ($str == ""){
     $str = '[]';
}

$arr = json_decode($str, true);

$arrne['name'] = "$theName";
$arrne['message'] = "$theMessage";

array_push($arr, $arrne);   

$aFinalTransaction = json_encode($arr, JSON_PRETTY_PRINT);
echo $aFinalTransaction;

file_put_contents("transactions.json", "$aFinalTransaction");

This gets the content of the transactions file, decodes it, insert the name and messages taken from $_GET, pushes it into the array and encodes it back into a string and puts it into the transactions file.

This works fine, however I need to do the exact same thing just for XML instead of JSON. So the string from the file would look something like this:

<chatMessage>
 <name>Name1</name>
 <message>Msg1</message>
</chatMessage>
<chatMessage>
 <name>Name2</name>
 <message>Msg2</message>
</chatMessage>

This is how is looks right now in JSON:

[
    {
        "name": "Name1",
        "message": "Msg1"
    },
    {
        "name": "Name2",
        "message": "Msg2"
    }
]

Also, one more thing, how exactly would I name that JSON object? So it'd look something like this instead:

{"messages":[
    {
        "name": "Name1",
        "message": "Msg1"
    },
    {
        "name": "Name2",
        "message": "Msg2"
    }
]}

This last part is probably easier than I think, but I haven't had any luck.

I really hope you can help me. Thanks.

Answer 1

If you want to have your "messages" under an element of that name, you just need to make sure your array follows that format. You are also not defining $arrne, you need to set it to an array() first, which you can shorthand as seen below.

$str = file_get_contents( "transactions.json" );

// check if $str is a blank string, false, null, etc
if ( empty( $str ) ){
    // it's empty so create an array
    $arr = array();
} else {
    // it's not empty so decode the JSON string
    $arr = json_decode( $str, true );
}

// use isset() to avoid undefined index warnings
array_push( $arr, array(
    'name' => isset( $_GET['name'] )? $_GET['name'] : "",
    'message' => isset( $_GET['message'] )? $_GET['message'] : "",
) ); 

// assign to a new array with all the messages under the key "messages"
$result = array( 'messages' => $arr );

// convert array to JSON. see comment above for converting to XML with SimpleXML
$json = json_encode( $result, JSON_PRETTY_PRINT );