Error : Array to string conversion in PHP - php

Question

I'm getting this error while trying to execute my function.
The columns of my database are 100% correct and i tested every request and it worked!
Error :
[26-May-2018 05:21:49 UTC] PHP Notice: Array to string conversion in C:\wamp64\www\gcm\database.php on line 82
[26-May-2018 05:21:49 UTC] PHP Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given in C:\wamp64\www\gcm\database.php on line 88
My function:
function getHistoriqueNotification($user,$mdp){
$com = new DbConnect();
$message=array();
$sql="select UTLR_UID from adm_utilisateurs where UTLR_LOGIN='$user' and UTLR_MDP='$mdp'";
$result=mysqli_query($com->getDb(),$sql);
$getID = mysqli_fetch_assoc($result);
$userID = $getID['UTLR_UID'];
$sqli = "SELECT alr_alertes.ALRT_DES_LN1,alr_alertes.ALRT_PHOTO,alr_historiques.AHIS_DES_LN1,alr_historiques.AHIS_DATEHEURE from alr_alertes,alr_historiques WHERE alr_alertes.ALRT_UID=alr_historiques.ALRT_UID AND alr_historiques.UTLR_UID=$userID";
$resulti = mysqli_query($com->getDb(),$sqli);
while($row=mysqli_fetch_assoc($resulti)){
$message = array('photo' =>$row['ALRT_PHOTO'] , 'titre' => $row['ALRT_DES_LN1'] , 'dateHeure' =>$row['AHIS_DATEHEURE'] , 'detail' => $row['AHIS_DES_LN1']);
}
return $message;
}

Answer 1

When using mysqli you need to free up the results per each query. Since you made a query with the $sql and then a second query using the $sqli without freeing up the results in between the two queries it caused you the problem.
Please read on these mysqli functions:
http://php.net/manual/en/mysqli-result.free.php
Notice I closed your first connection and then made a second one. I think you can do this by keeping the same connection but calling mysqli_free_result() prior to your next query. I am not all that familiar with mysqli but I think that's right.
function getHistoriqueNotification($user, $mdp){
$com = new DbConnect();
$message=array();
$sql = "select UTLR_UID from adm_utilisateurs where UTLR_LOGIN='$user' and UTLR_MDP='$mdp'";
$result = mysqli_query($com->getDb(),$sql);
$getID = mysqli_fetch_assoc($result);
$userID = $getID['UTLR_UID'];
mysqli_close($com);
unset($com);
$com1 = new DbConnect(); //This is really just a test.
$sqli = "SELECT alr_alertes.ALRT_DES_LN1,alr_alertes.ALRT_PHOTO,alr_historiques.AHIS_DES_LN1,alr_historiques.AHIS_DATEHEURE from alr_alertes,alr_historiques WHERE alr_alertes.ALRT_UID=alr_historiques.ALRT_UID AND alr_historiques.UTLR_UID=$userID";
if ($resulti = mysqli_query($com1->getDb(), $sqli)){
while($row = mysqli_fetch_assoc($resulti)){
//Added the [] after message.
$message[] = array(
'photo' =>$row['ALRT_PHOTO'],
'titre' =>$row['ALRT_DES_LN1'],
'dateHeure' =>$row['AHIS_DATEHEURE'],
'detail' =>$row['AHIS_DES_LN1']
);
}
}else{
echo("Error description: " . mysqli_error($com1->getDb()));
}
print_r($message); //<---This will show you if you have a result.
return $message;
}