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_result::fetch_object
mysqli_fetch_object
(PHP 5)
mysqli_result::fetch_object -- mysqli_fetch_object — Devuelve la fila actual de un conjunto de resultados como un objeto
Descripción
Estilo orientado a objetos
object mysqli_result::fetch_object
([ string
$class_name
[, array $params
]] )Estilo por procedimientos
mysqli_fetch_object() devolverá la fila actual del conjunto de resultados como un objeto, donde los atributos del objeto representan los nombres de los campos encontrados en el conjunto de resultados.
Observe que mysqli_fetch_object() establece las propiedades del objeto antes de llamar al constructor del objeto.
Parámetros
-
result -
Sólo estilo por procedimientos: Un conjunto de identificadores de resultados devuelto por mysqli_query(), mysqli_store_result() o mysqli_use_result().
-
class_name -
El nombre de la clase a instanciar, establecer las propiedades y devolver. Si no se especifica se devuelve un objeto stdClass.
-
params -
Un array opcional de parámetros para pasar al constructor de los objetos de
class_name.
Valores devueltos
Devuelve un objeto con las propiedades de cadena que corresponden a la fila
obtenida o NULL si no hay más filas en el conjunto de resultados.
Nota: Los nombres de los campos devueltos por esta función son sensibles a mayúsculas y minúsculas.
Nota: Esta función define campos NULOS al valor
NULLde PHP.
Historial de cambios
| Versión | Descripción |
|---|---|
| 5.0.0 | Se añadió la capacidad para devolver como un objeto diferente. |
Ejemplos
Ejemplo #1 Estilo orientado a objetos
<?php
$mysqli = new mysqli("localhost", "mi_usuario", "mi_contraseña", "world");
/* comprobar la conexión */
if (mysqli_connect_errno()) {
printf("Falló la conexión: %s\n", mysqli_connect_error());
exit();
}
$consulta = "SELECT Name, CountryCode FROM City ORDER by ID DESC LIMIT 50,5";
if ($resultado = $mysqli->query($consulta)) {
/* obtener el array de objetos */
while ($obj = $resultado->fetch_object()) {
printf ("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
/* liberar el conjunto de resultados */
$resultado->close();
}
/* cerrar la conexión */
$mysqli->close();
?>
Ejemplo #2 Estilo por procedimientos
<?php
$enlace = mysqli_connect("localhost", "mi_usuario", "mi_contraseña", "world");
/* comprobar la conexión */
if (mysqli_connect_errno()) {
printf("Falló la conexión: %s\n", mysqli_connect_error());
exit();
}
$consulta = "SELECT Name, CountryCode FROM City ORDER by ID DESC LIMIT 50,5";
if ($resultado = mysqli_query($enlace, $consulta)) {
/* obtener el array asociativo */
while ($obj = mysqli_fetch_object($resultado)) {
printf ("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
/* liberar el conjunto de resultados */
mysqli_free_result($resultado);
}
/* cerrar la conexión */
mysqli_close($enlace);
?>
El resultado de los ejemplos serían:
Pueblo (USA) Arvada (USA) Cape Coral (USA) Green Bay (USA) Santa Clara (USA)
Ver también
- mysqli_fetch_array() - Obtiene una fila de resultados como un array asociativo, numérico, o ambos
- mysqli_fetch_assoc() - Obtiene una fila de resultado como un array asociativo
- mysqli_fetch_row() - Obtener una fila de resultados como un array enumerado
- mysqli_query() - Realiza una consulta a la Base de Datos
- mysqli_data_seek() - Ajustar el puntero de resultado a una fila arbitraria del resultado
add a note
User Contributed Notes
mysqli_result::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.