(PHP 5, PHP 7, PHP 8)
mysqli_result::fetch_object -- mysqli_fetch_object — Returns the current row of a result set as an object
面向对象风格
$class = "stdClass"
, array $constructor_args = []
) : object|null|false过程化风格
$result
, string $class = "stdClass"
, array $constructor_args = []
) : object|null|falseReturns the current row result set as an object where the attributes of the object represent the names of the fields found within the result set.
Note: This function sets the properties of the object before calling the object constructor.
Note: 此函数返回的字段名大小写敏感。
Note: 此函数将 NULL 字段设置为 PHP
null值。
result仅以过程化样式：由 mysqli_query()、mysqli_store_result()、 mysqli_use_result()、mysqli_stmt_get_result() 返回的结果集标识。
classThe name of the class to instantiate, set the properties of and return. If not specified, a stdClass object is returned.
constructor_args
An optional array of parameters to pass to the constructor
for class objects.
Returns an object that corresponds to the fetched
row or null if there are no more rows in result set.
| 版本 | 说明 |
|---|---|
| 8.0.0 |
constructor_args now accepts [] for constructors with 0 parameters;
previously an exception was thrown.
|
Example #1 mysqli_result::fetch_object() example
面向对象风格
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
$query = "SELECT Name, CountryCode FROM City ORDER BY ID DESC";
$result = $mysqli->query($query);
/* fetch object array */
while ($obj = $result->fetch_object()) {
printf("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
过程化风格
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
$query = "SELECT Name, CountryCode FROM City ORDER BY ID DESC";
$result = mysqli_query($link, $query);
/* fetch associative array */
while ($obj = mysqli_fetch_object($result)) {
printf("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
以上例程的输出类似于：
Pueblo (USA) Arvada (USA) Cape Coral (USA) Green Bay (USA) Santa Clara (USA)
I checked the bug database and as long as your PHP installation is up to date, the order of setting properties and calling the constructor should now follow the order specified in the documentation. There was a little while that a patch had been introduced where it was happening the other way around but that has been fixed now.
Note that if you supply a class that has a __set() magic method defined in it, that method will be called for any properties that are not defined in your class. For example:
<?php
class SomeClass {
private $id;
public $partner_name;
public function __set( $name, $value ) {
echo "__set was called! Name = $name\n";
$this->$name = $value;
}
}
$db = new mysqli( 'localhost', 'Username', 'Password', 'DbName' );
$result = $db->query( 'SELECT id, partner_name, partner_type FROM submissions' );
$object = $result->fetch_object( 'SomeClass' );
?>
Produces the following output:
__set was called! Name = partner_type
Since 5.6.21 and PHP 7.0.6
mysqli_fetch_object() sets the properties of the object AFTER calling the object constructor. Not BEFORE as was in previous versions.
So behaviour has changed. Seems a bug but not sure if was done intentionally.
https://bugs.php.net/bug.php?id=72151
Please mind the difference between objects and arrays in PHP>=5: arrays are by value while objects are by reference.
<?
$o = mysqli_fetch_object($res);
$o1 = $o;
$o1->value = 10;
$a = mysqli_fetch_array($res);
$a1 = $a;
$a1['value'] = 10;
echo $o->value; // 10
echo $a['value']; // (original value from db)
?>
Should same behaviour be intended, the object needs to be cloned:
<?
$o1 = clone $o;
?>
More about object cloning:
http://php.net/manual/en/language.oop5.cloning.php
As a best practice, if you intend to use a defined class when using fetching_object(). Put the data obtaining code within a static method of the defined class. Otherwise, wherever you include the file (if not using an autoloader) the data connection will occur whether you want it to or not.
For example:
<?php
class User
{
public $name;
public static function getUser($id)
{
$conn = new mysqli('localhost', 'username', 'password', 'database');
if ($result = $conn->query("SELECT * FROM users WHERE id = {$id} LIMIT 1")) {
return $result->fetch_object('User');
$result->close();
}
}
}
?>
Call the static method to obtain an instance of the User class with your data applied to it.
<?php
$user = User::getUser('31');
echo $user->name; // echo's 'Phil'
?>
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.
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');
}
}
?>
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
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.