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, PHP 7, PHP 8)
mysqli_result::fetch_object -- mysqli_fetch_object — Fetch the next row of a result set as an object
说明
面向对象风格
public mysqli_result::fetch_object(string
$class = "stdClass", array $constructor_args = []): object|null|false过程化风格
mysqli_fetch_object(mysqli_result
$result, string $class = "stdClass", array $constructor_args = []): object|null|false
Fetches one row of data from the result set and returns it as an object,
where each property represents the name of the result set's column.
Each subsequent call to this function will return the next row within the
result set, or null if there are no more rows.
If two or more columns of the result have the same name, the last column will take precedence and overwrite any previous data. To access multiple columns with the same name, mysqli_fetch_row() may be used to fetch the numerically indexed array, or aliases may be used in the SQL query select list to give columns different names.
注意: This function sets the properties of the object before calling the object constructor.
注意: 此函数返回的字段名大小写敏感。
注意: 此函数将 NULL 字段设置为 PHP
null值。
参数
-
result -
仅以过程化样式：由 mysqli_query()、mysqli_store_result()、 mysqli_use_result()、mysqli_stmt_get_result() 返回的 mysqli_result 对象。
-
class -
The 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
classobjects.
返回值
Returns an object representing the fetched row, where each property
represents the name of the result set's column, null if there
are no more rows in the result set, 或者在失败时返回 false.
错误／异常
A ValueError is thrown when
the constructor_args is non-empty with the class not having constructor.
更新日志
| 版本 | 说明 |
|---|---|
| 8.3.0 |
Now throws a ValueError exception when
the constructor_args is non-empty with the class not having constructor;
previously an Exception was thrown.
|
| 8.0.0 |
constructor_args now accepts [] for constructors with 0 parameters;
previously an exception was thrown.
|
示例
示例 #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);
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, $query);
while ($obj = mysqli_fetch_object($result)) {
printf("%s (%s)\n", $obj->Name, $obj->CountryCode);
}以上示例的输出类似于：
Pueblo (USA) Arvada (USA) Cape Coral (USA) Green Bay (USA) Santa Clara (USA)
参见
- mysqli_fetch_array() - Fetch the next row of a result set as an associative, a numeric array, or both
- mysqli_fetch_assoc() - Fetch the next row of a result set as an associative array
- mysqli_fetch_column() - Fetch a single column from the next row of a result set
- mysqli_fetch_row() - Fetch the next row of a result set as an enumerated array
- mysqli_query() - 对数据库执行查询
- mysqli_data_seek() - Adjusts the result pointer to an arbitrary row in the result
add a note
User Contributed Notes 5 notes
Driek ¶
12 years ago
object-array at gmail dot com ¶
8 years ago
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
neo22s at gmail dot com ¶
8 years ago
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
macole at paypal dot com ¶
8 years ago
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
benpptung at tacol dot biz ¶
15 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
