PHP：递归获取父级的子级 [英] PHP: Recursively get children of parent

问题描述

我有一个函数，可从数据库中获取父级所有子级的ID。因此，如果我查找id 7，它可能会返回包含5、6和10的数组。然后，我要递归地找到返回的id的孩子，依此类推，直到孩子的最终深度。

I have a function which gets the ids of all children of a parent from my DB. So, if I looked up id 7, it might return an array with 5, 6 and 10. What I then want to do, is recursively find the children of those returned ids, and so on, to the final depth of the children.

我试图编写一个函数来执行此操作，但是我对递归感到困惑。

I have tried to write a function to do this, but I am getting confused about recursion.

function getChildren($parent_id) {
    $tree = Array();
    $tree_string;
    if (!empty($parent_id)) {
        // getOneLevel() returns a one-dimentional array of child ids
        $tree = $this->getOneLevel($parent_id);
        foreach ($tree as $key => $val) {
            $ids = $this->getChildren($val);
            array_push($tree, $ids);
            //$tree[] = $this->getChildren($val);
            $tree_string .= implode(',', $tree);
        }

        return $tree_string;
    } else {
        return $tree;
    }

}//end getChildren()

之后函数运行后，我希望它返回找到的所有子ID的一维数组。

After the function is run, I would like it to return a one-dimentional array of all the child ids that were found.

推荐答案

这项工作对我来说很好：

This work fine for me:

function getOneLevel($catId){
    $query=mysql_query("SELECT categoryId FROM categories WHERE categoryMasterId='".$catId."'");
    $cat_id=array();
    if(mysql_num_rows($query)>0){
        while($result=mysql_fetch_assoc($query)){
            $cat_id[]=$result['categoryId'];
        }
    }   
    return $cat_id;
}

function getChildren($parent_id, $tree_string=array()) {
    $tree = array();
    // getOneLevel() returns a one-dimensional array of child ids        
    $tree = $this->getOneLevel($parent_id);     
    if(count($tree)>0 && is_array($tree)){      
        $tree_string=array_merge($tree_string,$tree);
    }
    foreach ($tree as $key => $val) {
        $this->getChildren($val, &$tree_string);
    }   
    return $tree_string;
}

调用 getChildren（yourid）;
然后它将返回给定节点/父级的完整子级数组。

Call the getChildren(yourid); Then it will return the complete array of children for that given node/parent.

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