PHP：使用递归函数从多数组中搜索并返回值

Question

I have a multi-dimensional array of objects (see sample data below). Now I want to search a value (or property) in the data. If the value is found, the function should return the right object and stop searching.

I found three solutions to do this with a recursive function. But nothing works like described above.

The first is my own solution:

public static function getPathForUrl($folderContentDetails, string $url, $result = NULL)
{
    foreach($folderContentDetails as $key => $item)
    {
        if($item->url === $url)
        {
            $result = $item;
        }
        elseif($item->elementType === "folder")
        {
            $result = self::getPathForUrl($item->folderContent, $url, $result);
        }
    }
    return $result;
}

If you call the function like this:

print_r(self::getPathForUrl($data, 'order/abc/alpha');

then it returns the right object. The downside is, that the function searches the whole data and finally returns the result. I did not find a way to stop the function, if a result is found, so its wasting resources.

The second (standard-)solution that you will find in the web, looks like this:

public static function getPathForUrl($folderContentDetails, string $url)
{
    foreach($folderContentDetails as $key => $item)    
    {
        if($url === $item->url OR ($item->elementType == "folder" && Folder::getPathForUrl($item->folderContent, $url) !== false)) 
        {
            print_r('inner: <br/>'.$item->url);
            // prints more then one value, depending on your data, in my case :
            // /order/abc/alpha
            // /order/abc
            // /order
            return $item;
        }
    }
    return false;
}

This function stops, if it finds the right value. But for some reason it returns more than one object, and the final object is wrong (see code-comments).

The last solution looks like this:

public static function getPathForUrl($folderContentDetails, string $url)
{           
    foreach($folderContentDetails as $key => $item)
    {
        if($item->elementType == "folder" && $item->url != $url)
        {
            return self::getPathForUrl($item->folderContent, $url); 
            // iterates only the first sub-folder, then stops
        }
        elseif($item->url == $url)
        {
            print_r($item); //nothing, if not found in first sub-folder
            return $item; // nothing, if not found in first sub-folder
        }
    }
    return false;
}

If you return the result of the recursive function, then the function goes down to the first nested element and stops there, so it does not go up again to search the other elements.

If you do not return the result, the function searches the whole data but, of course, does not return the right object.

I probably do not understand the concept of recursion properly. Any help is highly welcome.

These are some sample data:

Array
(
[0] => stdClass Object
    (
        [elementType] => folder
        [path] => 
        [url] => /getting-started
        [folderContent] => Array
            (
                [0] => stdClass Object
                    (
                        [elementType] => file
                        [path] => \0_getting_started\01-installation.md
                        [url] => /getting-started/installation
                    )

                [1] => stdClass Object
                    (
                        [elementType] => file
                        [path] => \0_getting_started\02-system-settings.md
                        [url] => /getting-started/system-settings
                    )

                [2] => stdClass Object
                    (
                        [elementType] => file
                        [path] => \0_getting_started\index.md
                        [url] => /getting-started/index
                    )

            )

    )

[1] => stdClass Object
    (
        [elementType] => folder
        [path] => 
        [url] => /order
        [folderContent] => Array
            (
                [0] => stdClass Object
                    (
                        [elementType] => folder
                        [path] => \2_order
                        [url] => /order/abc
                        [folderContent] => Array
                            (
                                [0] => stdClass Object
                                    (
                                        [elementType] => file
                                        [path] => \2_order\abc\alpha.md
                                        [url] => /order/abc/alpha
                                    )
                            )

                    )
            )

    )

[3] => stdClass Object
    (
        [elementType] => file
        [path] => \index.md
        [url] => /index
   )
)

Answer 1

Return exits the function so if you want the first result just return it in your condition

public static function getPathForUrl($folderContentDetails, string $url, $result = NULL)
{
    foreach($folderContentDetails as $key => $item)
    {
        if($item->url === $url)
        {
            return $item;
        }
        elseif($item->elementType === "folder")
        {
            $result = self::getPathForUrl($item->folderContent, $url, $result);
        }
    }
    return $result;
}

Answer 2

If you want to stop after a match of value is made; just return inside the condition;

public static function getPathForUrl($folderContentDetails, string $url, $result = NULL)
{
    foreach($folderContentDetails as $key => $item)
    {
        if($url === $item->url)
        {
            return $item;
        }

        if("folder" === $item->elementType)
        {
          return self::getPathForUrl($item->folderContent, $url, $result);
        }
    }
}

PS: Keeping in mind Best practices for if/return :)