(PHP 5, PHP 7, PHP 8)
mysqli_result::fetch_object -- mysqli_fetch_object — 結果セットの次の行を取得し、オブジェクトとして返す
オブジェクト指向型
$class = "stdClass", array $constructor_args = []): object|null|false手続き型
$result, string $class = "stdClass", array $constructor_args = []): object|null|false
結果セットから1行取得し、それをオブジェクトとして返します。
このオブジェクトは、結果セットのカラム名をプロパティとして持ちます。
値を取得した後は、この関数をコールするたびに結果セットの次の行の値を返します。
もう結果セットに行がない場合には null を返します。
もし2つ以上のカラムが同じ名前であった場合は、最後に現れた カラムが優先され、以前のあらゆるデータを上書きします。同名の複数のカラムに アクセスする場合、mysqli_fetch_row() を用いて 数値添字配列を使用するか、あるいは SQL クエリ中の SELECT リストに異なる名前を与えるために、カラムにエイリアスを指定する 必要があります。
注意: この関数がオブジェクトのプロパティを設定するのは、 オブジェクトのコンストラクタをコールする前であることに注意しましょう。
注意: この関数により返されるフィー ルド名は 大文字小文字を区別 します。
注意: この関数は、 NULL フィールドに PHPの
null値を設定します。
result手続き型のみ: mysqli_query()、mysqli_store_result()、mysqli_use_result()、mysqli_stmt_get_result() が返す mysqli_result オブジェクト。
classインスタンス化してプロパティを設定後に返すクラスの名前。 省略した場合は stdClass オブジェクトを返します。
constructor_args
オプションのパラメータの配列で、
class オブジェクトのコンストラクタに渡します。
取得した行を表すオブジェクトを返します。
これは、個別のプロパティが結果セットのカラム名を表します。
結果セットにもう行がない場合には null を返します。
失敗した場合に false を返します
| バージョン | 説明 |
|---|---|
| 8.0.0 |
constructor_args は、
引数を指定しない場合に []
を受け入れるようになりました。
これより前のバージョンでは、例外がスローされていました。
|
例1 mysqli_result::fetch_object() の例
オブジェクト指向型
<?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);
/* オブジェクトの配列を取得します */
while ($obj = $result->fetch_object()) {
printf("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
手続き型
<?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, $query);
/* 連想配列を取得します */
while ($obj = mysqli_fetch_object($result)) {
printf("%s (%s)\n", $obj->Name, $obj->CountryCode);
}
上の例の出力は、 たとえば以下のようになります。
Pueblo (USA) Arvada (USA) Cape Coral (USA) Green Bay (USA) Santa Clara (USA)
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 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.
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
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
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
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.
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.
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');
}
}
?>
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'
?>
