如何从 foreach 中获取确定值

Question

我正在创建用户树保存在.json文件中，但是我在二级用户中找不到读取第三方用户的方法

通过一个 foreach，mysql 的次级用户阅读了我的内容，但它没有将他们与第三个用户对齐我的桌子是

1.(用户名=juan referedby=none)

2.(用户名=jose referedby=juan)

3.(用户名=alberto referedby=juan)

4.（用户名=fernando referedby=jose）

`` php


$stmt = $mysqli->prepare("SELECT username FROM affiliateuser WHERE referedby = '$actualuser'");
$stmt->execute();
$array = [];
foreach ($stmt->get_result() as $row)
{
    $referedby[] = $row['username'];

}
$string = '';
$string2 = '';
foreach ($referedby as $key => $secundaryusers){
}` ``

我希望结果能给我这样的结果。

    { "name": "juan ", "children": [ { "name ": "jose", "children": [{ "name": "fernando", "children": [] }] } { "name": "alberto", "children": [] } ] },

Answer 1

这里的想法是创建一个 PHP 结构，其数据与 JSON 中存在的数据相同，然后使用 json_encode() 将该结构转换为 JSON .

如果您查看 class User，它代表一个用户和所有后代。如果我可以用所有数据填充它，那么将它转换成 JSON 就很容易了。

请注意，table 中的每个用户都有一个存储在列 referredby_id 中的父级。这是父用户的主键。只要保证 table 中的用户名是唯一的，您就可以将其更改为用户名。为此，将 referredby_id 列的类型更改为 VARCHAR。如果数据量大，则索引用户名table.

Table:

CREATE TABLE `affilitateuser` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `username` varchar(40) DEFAULT NULL,
  `referredby_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

数据：

INSERT INTO `affilitateuser` (`id`, `username`, `referredby_id`) VALUES
(1, 'sarah', NULL),
(2, 'james', 1),
(3, 'tom', 2),
(4, 'natalie', 3),
(5, 'juan', NULL),
(6, 'jose', 5),
(7, 'alberto', 5),
(8, 'fernando', 5),
(9, 'camila', 8),
(10, 'sean', 9),
(11, 'scotty', 9),
(12, 'robert', 9),
(13, 'montgomery', 12),
(14, 'jessie', 13),
(15, 'cole', 13),
(16, 'cary', 14),
(17, 'porter', 14),
(18, 'sandra', 5),
(19, 'lily', 6);

代码：

// A class to represent nodes on a tree
class User
{
    public $name;
    public $children = [];
    public function __construct($name)
    {
        $this->name = $name;
    }
    // Add a child to this User
    public function addChild($name)
    {
        $u = new User($name);
        $this->children[] = $u;
        // return the newly created object so we can use it later.
        return $u;
    }
}

// Class that does the extracting
class UserTreeExtractor
{
    protected $conn; // keep the database connection

    public function run()
    {
        $this->connect();
        // Extract Juan's tree
        // print_r($this->tree(5));
        // Save the JSON to a string
        $jsonString = json_encode($this->tree(5), JSON_PRETTY_PRINT);
        // Write it out to a file
        file_put_contents('output.json', $jsonString);
    }
    // { "name": "juan ", "children": [ { "name ": "jose", "children": [{ "name": "fernando", "children": [] }] } { "name": "alberto", "children": [] } ] },

    /**
     * Gets the children and downstream descendants for a user
     */
    protected function tree($id)
    {
        // First, get the user
        $sql1 = "SELECT username FROM affilitateuser WHERE id = {$id}";
        $stmt = $this->conn->prepare($sql1);
        if ( ! $stmt ) {
            die('query failed');
        }
        $stmt->execute();
        $top = $stmt->get_result()->fetch_assoc();
        // print_r($top); exit();

        // Now get the all descendents
        $sql = "SELECT  id, username, referredby_id 
        FROM    (SELECT * FROM affilitateuser
        ORDER BY referredby_id, id) users_sorted,
        (SELECT @pv := '{$id}') initialisation
        WHERE   find_in_set(referredby_id, @pv)
        AND     LENGTH(@pv := CONCAT(@pv, ',', id))";
        // "SELECT username FROM `affiliateuser` WHERE referedby_id = {$id}"
        $stmt = $this->conn->prepare($sql);
        $stmt->execute();
        $children = [];
        $tree = new User($top['username']);
        // Keep an index of where the objects are stored
        // so we can find them later to attach their children.
        $index[$id] = $tree;
        $parent = null;
        foreach ($stmt->get_result() as $row)
        {
            if ( isset($index[$row['referredby_id']]) ) {
                $new = $index[$row['referredby_id']]->addChild($row['username']);
                $index[$row['id']] = $new; // put the new user into the index
            } else {
                // referred by some user that does not exist
                die("Referred by non-existent user");
            }
            $children[] = ['username' => $row['username'], 'id' => $row['id'], 'referredby_id' => $row['referredby_id']];
        }
        return $tree;
    }
    // Connect to the database
    protected function connect()
    {
        // Change the connection credentials as needed.
        $this->conn = mysqli_connect("127.0.0.1", "app", "aaaa", "sss"); 
        if( ! $this->conn ) { 
            die("Database Connection Failed: ".mysql_error()); 
        }
    }
}

$obj = new UserTreeExtractor;
$obj->run();

如何从 foreach 中获取确定值

how to to obtain a determine values from a foreach

php

mysql

php-7