在PHP中将所有行元素打印为树 [英] Printing down all row elements as tree in PHP

问题描述

我建立了一个数据库，该数据库具有一个称为任务的表。表格任务负责按任务的第一个输入日期顺序对其进行保存。任务表具有名为父的列。该父列使用户可以在另一个任务下创建新任务。例如，我们有一个任务，其ID为21。当在第21个任务下创建一个新的子任务时，将新任务的父列设置为21；将第一个任务的父列设置为21。因此它意味着新任务是第21个任务下的任务。我附上一张桌子的图片，以便您更容易了解发生了什么。
http://i.stack.imgur.com/M9cmZ.jpg

I built a database that has a table called "tasks". Table tasks is in charge of keeping tasks in order of their first entry date. Tasks table has a column named "parent". This parent column enables user to create a new task under another task. For example we have a task, its id is 21. When we create a new "child" task under 21th task, we set parent column of new task to 21; so that it implies that new task is a task under 21th task. I included an image of table so that it gets easier to understand what's going on. http://i.stack.imgur.com/M9cmZ.jpg

我要用所有这些任务来实现的目的是，我希望它们以树的形式打印出来，如果可以的话，它们是无序列表。列表的结构如下：

What I am trying to achieve with all those tasks is that I want them printed out as tree, a unordered list if you may. Structure of the list is like following:

<ul id="tree">
        <li><a href="#">A root Task</a>
            <ul>
                <li><a href="#">child of first task</a>
                    <ul>
                        <li><a href="#">grandchildren of first child</a></li>
                        <li><a href="#">grandchildren of first child</a></li>
                    </ul>                           
                </li>
                <li><a href="#">child of first task</a></li>
                <li><a href="#">child of first task</a>
                    <ul>
                        <li><a href="#">grandchildren of first child</a></li>
                        <li><a href="#">grandchildren of first child</a></li>
                        <li><a href="#">grandchildren of first child</a></li>
                    </ul>                           
                </li>
                <li><a href="#">child of first task</a>
                    <ul>
                        <li><a href="#">grandchildren of first child</a></li>

                    </ul>                           
                </li>
                <li><a href="#">child of first task</a></li>
            </ul>                   
        </li>
</ul>

我想出了两个主意，但都没有用。

I came up with couple of ideas, none of them is working. Is there any ideas for that?

上面示例中的根任务是任务表中的任务，其父值为0。其中可能有很多，无父任务，并且在另一个任务下创建任务没有限制。

A root task in the example above is a task from tasks table that its parent value is 0. There may be a lot of them, parentless tasks, and there will no limit on creating task under another.

推荐答案

也许您已经想到了这一点..但是..

Maybe you have thought of that.. but..

我想到的第一个主意是一个简单的函数，该函数将返回与给定parent_id匹配的所有子代。.

The first idea that comes to my mind is a simple function that returns all the childs that match with the given parent_id..

因此，第一个调用是 get_childs（0），他将以 parent_id ='0'返回所有任务。

So, the first call is get_childs(0), and he will return all the Tasks with parent_id='0'.

然后，每个函数都会再次调用相同的函数，并带有其父母的id。
如果主要任务之一的 id = 50 并且表中存在 parent_id = 50 ，

And each one, will call again the same function, with his parents id on it. If one of the main tasks has id=50, and in the table exists parent_id=50, they will print under his parent.

function get_childs($parent_id){

     if ($result = $mysqli->query("SELECT * FROM table WHERE parent_id='".$parent_id."'")) {
         echo '<ul>';

         while ($row = $result->fetch_assoc()) {
             echo '<li><a href="#">'.$row['name'].'</a>';

             //call again for each child. if the id dosen't have childs, then prints nothing and go on!
             get_childs($row['id']);

             echo '</li>';
        }// end while

        echo '</ul>';
     }// end if select

} // end function

希望有帮助！

这篇关于在PHP中将所有行元素打印为树的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！