mysqli_result::fetch_fields
As indicated in the user comments of the mysql_fetch_object, it is important to realize that class fields get values assigned to them BEFORE the constructor is called.
For example;
<?php
class Employee
{
private $id;
public function __construct($id = 0)
{
$this->id = $id;
}
}
// some code for creating a database connection... i.e. mysqli object
....
$result = $con->query("select id, name from employees");
$anEmployee = $result->fetch_object("Employee");
?>
will result in the ID being 0 because it is overridden by the constructor. Therefore, it is useful to check if the class field is already set.
I.e.
<?php
class Employee
{
private $id;
public function __construct($id = 0)
{
if (!$this->id)
{
$this->id = $id
}
}
}
?>
Also note that the fields which will be assigned by fetch_object are case sensitive. If your table has the field "ID", it will result in the class field $ID being set. A simple work-around is to use aliases. I.e. "SELECT *, ID as id FROM myTable"
I hope this helps some people.
mysqli_fetch_object
result->fetch_object
(PHP 5)
mysqli_fetch_object -- result->fetch_object — Retorna a linha atual do conjunto de resultados como um objeto
Descrição
Estilo de procedimento:
Estilo orientado a objeto (metodo):
mixed
fetch_object
( void
)
A função mysqli_fetch_object() irá retornar a linha atual do conjunto de resultados
como um objeto aonde os atributos do objeto representam os nomes dos campos encontrados
no conjunto de resultados. Se não existirem mais linhas no conjunto de resultados atual, é retornado NULL.
Valores de retorno
Retorna um objeto que corresponde a linha obtida ou NULL se não houverem mais linhas no conjunto de resultados.
Nota: Nomes de campos nesta função diferenciam maiúsculas e minusculas.
Nota: Esta função assimila campos NULL para o o
NULLdo PHP.
Veja também
mysqli_fetch_array(), mysqli_fetch_assoc(), mysqli_fetch_row().
Exemplo
Exemplo #1 Estilo orientado a objeto
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$query = "SELECT Name, CountryCode FROM City ORDER by ID DESC LIMIT 50,5";
if ($result = $mysqli->query($query)) {
/* fetch object array */
while ($obj = $result->fetch_object()) {
printf ("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
/* free result set */
$result->close();
}
/* close connection */
$mysqli->close();
?>
Exemplo #2 Estilo de procedimento
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$query = "SELECT Name, CountryCode FROM City ORDER by ID DESC LIMIT 50,5";
if ($result = mysqli_query($link, $query)) {
/* fetch associative array */
while ($obj = mysqli_fetch_object($result)) {
printf ("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
/* free result set */
mysqli_free_result($result);
}
/* close connection */
mysqli_close($link);
?>
Os exemplos acima devem produzir a seguinte saída:
Pueblo (USA) Arvada (USA) Cape Coral (USA) Green Bay (USA) Santa Clara (USA)
add a note
User Contributed Notes
mysqli_fetch_object - [5 notes]
Driek ¶
10 months ago
benpptung at tacol dot biz ¶
3 years ago
I don't know why no one talk about this.
fetch_object is very powerful since you can instantiate an Object which has the methods you wanna have.
You can try like this..
<?php
class PowerfulVO extends AbstractWhatEver {
public $field1;
private $field2; // note : private is ok
public function method(){
// method in this class
}
}
$sql = "SELECT * FROM table ..."
$mysqli = new mysqli(........);
$result = $mysqli->query($sql);
$vo = $result->fetch_object('PowerfulVO');
?>
Note : if the field is not defined in the class, fetch_object will add this field for you as public.
The method is very powerful, especially if you want to use a VO design pattern or class mapping feature with Flex Remoting Object( Of course, you need to have ZendAMF or AMFPHP ..framework)
Hope this help and open new possibilities for you
jorortega at gmail dot com ¶
10 months ago
Be aware that, since the class fields get values assigned to them BEFORE the constructor is called, the...
if ($result = $mysqli->query($query)) {
...statement in some cases has not sense. At all.
Using some example:
$query = "SELECT * FROM City WHERE Country='some country'";
If 'some country' doesn't exist, $query won't be FALSE like with the good old days, but will be an object with some predefined fields. Thus, in this case, the if statement is useles, as it will always be TRUE.
In this case, is best to check the object property "num_rows" :
if ($result->num_rows != 0) ...
because if the query fails, num_rows will be asigned the number 0 (integer), and thus, you will know the query failed.
Alex ¶
1 year ago
Make sure to specify the full namespace for the "string $class_name" parameter and not a partial one, as it won't find it. For example:
<?php
namespace Root(backslash)FirstLevel
{
public static function Test($result)
{
return mysqli_fetch_object($result, 'SecondLevel\\MyClass');
}
}
?>
... will not work but this will:
<?php
namespace Root(backslash)FirstLevel
{
public static function Test($result)
{
return mysqli_fetch_object($result, 'Root\\FirstLevel\\SecondLevel\\MyClass');
}
}
?>
peterbelm at g[oogle]mail dot com ¶
4 years ago
If your SQL code selects columns with empty names like so:
SELECT id as ``...
You will get a fatal error "Cannot access empty property", this took me a while to track down!
Obviously your SQL really shouldn't do that, and should be fixed but I'm going to submit a feature request to ask for a better error message for that.