如何在最多 4 个级别的树中选择类别 [英] How I can select categories in a tree upto 4 levels

问题描述

我正在尝试创建层次结构/树中所有类别的二维数组.

I am trying to create two dimensional array of all categories in hierarchy/tree.

因此，先是父类别，然后是其子类别，然后是第 3 级类别，然后是第 4 级.

So parent come first then its subcategories then 3rd level categories and then 4th level.

我有这样的记录表

 cc_id    category_name   parent_id  level
  1          general         0         1
  2          Books           1         2
  3          Magazines       1         2
  4          English Book    2         3
  5          Love Story      4         4

我想要这样的输出

Array
(
[0] => Array
    (
        [cc_id] => 1
        [parent_id] => 0
        [category_name] => General
        [level] => 1
    )

[1] => Array
    (
        [cc_id] => 2
        [parent_id] => 1
        [category_name] => Books
        [level] => 2
    )

[2] => Array
    (
        [cc_id] => 4
        [parent_id] => 2
        [category_name] => English Book
        [level] => 3
    )
    [3] => Array
    (
        [cc_id] => 4
        [parent_id] => 3
        [category_name] => Love Story
        [level] => 4
    )
    [4] => Array
    (
        [cc_id] => 3
        [parent_id] => 1
        [category_name] => Magazine
        [level] => 2
    )

 )

如果我可以在同一页面上混合 html 和 php 代码，我可以实现这一点.但我使用的是 MVC 结构，所以这是我的要求，我以嵌套顺序创建一个数组.因为我不能在我的内部使用 if else 条件查看页面.

I can achieve this If I can mixup html and php code on the same page.But I am using MVC structure so this is my requirement I create a array in nested order.Because I can't use if else conditions inside my view page.

我在控制器/lib 文件中尝试的是

What I am trying in my controller/lib file is

    $result = $DB->query("SELECT *
    FROM " . DB_PREFIX . "classified_categoies 
    WHERE is_publish=1");
//------------------------------------------------
// Check if resultset contains any rows
//------------------------------------------------
if ($DB->num_rows($result))
{
    $i = 0;
    //------------------------------------------------
    // Fetch resultset
    //------------------------------------------------
    while( $obj = $DB->fetch_object($result) )
    {
        //------------------------------------------------
        // Set values
        //------------------------------------------------

        if($obj->parent_id==0 and $obj->level==1)
        {
        $entries_obj[$i]['category_id'] = $obj->cc_id;
        $entries_obj[$i]['parent_id'] = $obj->parent_id;
        $entries_obj[$i]['category_name'] = $obj->category_name;
        $entries_obj[$i]['level'] = $obj->level;
        $i++;
        }

        $result2 = $DB->query("SELECT *
        FROM " . DB_PREFIX . "classified_categoies 
        WHERE is_publish=1 AND parent_id=".$obj->cc_id." order by level asc");

        if ($DB->num_rows($result))
        {
            while( $obj2 = $DB->fetch_object($result2) )
            {
                if($obj->level==2)
                {
                    $entries_obj[$i]['category_id'] = $obj2->cc_id;
                    $entries_obj[$i]['parent_id'] = $obj2->parent_id;
                    $entries_obj[$i]['category_name'] = $obj2->category_name;
                    $entries_obj[$i]['level'] = $obj2->level;
                    $i++;
                }
            }

        }

    }

但是通过这样做，我最多可以得到 2 个级别的类别.似乎通过使用上述逻辑，我必须编写 4 个查询.你们有没有任何有效的方法可以提出建议.谢谢..

But by doing this I am able to get upto 2 level categories.It seems by using above logic I have to written 4 queries.Is there not any efficient way you people can suggest Please.thank you..

一般输出应该是这样的

    Genaral
        Books
           English books
               Love Story
        Magazines

但我想要二维数组的输出.

But I want output in two dimensional array.

推荐答案

递归方法可以做到...

A recursive method would do it...

// First get a simple array of recordset, not as efficient but serves our purpose, so avoid filtering by level...

$baseArray = array();

while( $obj = $DB->fetch_object($result) )
{
  $baseArray[$obj->cc_id] = new array('category_id' => $obj->cc_id,
                                      'category_name' => $obj->category_name,
                                      'parent_id' => $obj->parent_id,
                                      'level' => $obj->level);
}

// Now our recursive method

function getBookCategories($inputArray, $parent = 0, $level = 0){
    $tmpReturn = array();
    foreach($inputArray as $cc_id => $categoryArray){
        if($categoryArray['parent_id'] == $parent){
            $tmpReturn[$cc_id] = $categoryArray;
            if($level < 4){
                $tmpReturn[$cc_id]['children'] = array();
                $tmpReturn[$cc_id]['children'] = getBookCategories($inputArray, $cc_id, $level + 1);
            }
        } 
    }
    return $tmpReturn;

}

编辑

如果您希望它与 $baseArray 相同，则:

If you wish it the same as $baseArray then:

function getBookCategories2($inputArray, &$outputArray, $parent = 0, $level = 0){
    foreach($inputArray as $cc_id => $categoryArray){
        if($categoryArray['parent_id'] == $parent){
            $outputArray[] = $categoryArray;
            if($level < 4){
                getBookCategories2($inputArray, $outputArray, $cc_id, $level + 1);
            }
        } 
    }

}

$desiredArray = array();

getBookCategories2($baseArray, $desiredArray, 0, 0);

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