Laravel is invalid to add a field to a two-dimensional array

I want to add another preview field to each element below the pic field, but why is it printed out and not added to each element? Did I add it in the wrong way? 

foreach($res as $k=>$v){
    foreach($v["pic"] as $k2=>$v2){
        $v2["preview"]=uniqid();
    }
}
dd($res);

foreachdd($v2)

the original data is as follows 

array ( 0 => array ( "id" => 1, "uid" => 10001, "href" => "111111", "content" => "6666", "create_at" => 1513264258, "user" => array ( "id" => 1, "uid" => 10001, "email" => "5414@qq.com", "password" => "111000", "tel" => NULL, "role" => 0, "created_at" => NULL, ), "info" => array ( "uid" => 10001, "nickname" => "", "image" => "static/img/3.jpeg", ), "pic" => array ( 0 => array ( "id" => 1, "uid" => 10001, "href" => "111111", "path" => "static/img/0.jpg", "number" => 0, "create_at" => 1513264258, ), 1 => array ( "id" => 2, "uid" => 10001, "href" => "111111", "path" => "static/img/1.jpg", "number" => 0, "create_at" => 1521442222, ), 2 => array ( "id" => 5, "uid" => 10001, "href" => "111111", "path" => "static/img/0.jpg", "number" => 0, "create_at" => 22222, ), ), "likebar" => array ( 0 => array ( "href" => "111111", "uid" => "10001", ), 1 => array ( "href" => "111111", "uid" => "10001", ), "hot" => 2, "comments" => 3, "status" => true, ), "comments" => array ( 0 => array ( "id" => 1, "href" => "111111", "uid" => 10001, "comment" => "hahhahah", "time" => 14751452, ), 1 => array ( "id" => 2, "href" => "111111", "uid" => 10001, "comment" => "666", "time" => 14521415, ), 2 => array ( "id" => 3, "href" => "111111", "uid" => 10002, "comment" => "ffffff", "time" => 1522441, ), ), "userinfo" => array ( "uid" => 10001, "nickname" => "", "image" => "static/img/3.jpeg", ), "isFollow" => false, ), 1 => array ( "id" => 3, "uid" => 10001, "href" => "111333", "content" => "55555", "create_at" => 22542, "user" => array ( "id" => 1, "uid" => 10001, "email" => "5414@qq.com", "password" => "111000", "tel" => NULL, "role" => 0, "created_at" => NULL, ), "info" => array ( "uid" => 10001, "nickname" => "", "image" => "static/img/3.jpeg", ), "pic" => array ( 0 => array ( "id" => 6, "uid" => 10001, "href" => "111333", "path" => "static/img/0.jpg", "number" => 0, "create_at" => 0, ), ), "likebar" => array ( "hot" => 0, "comments" => 0, "status" => false, ), "comments" => array ( ), "userinfo" => array ( "uid" => 10001, "nickname" => "", "image" => "static/img/3.jpeg", ), "isFollow" => false, ), 2 => array ( "id" => 2, "uid" => 10002, "href" => "111222", "content" => "fffffffff", "create_at" => 211545220, "user" => array ( "id" => 2, "uid" => 10002, "email" => "5555@qq.com", "password" => "123123", "tel" => NULL, "role" => 0, "created_at" => NULL, ), "info" => array ( "uid" => 10002, "nickname" => "", "image" => "static/img/3.jpeg", ), "pic" => array ( 0 => array ( "id" => 3, "uid" => 10001, "href" => "111222", "path" => "static/img/0.jpg", "number" => 0, "create_at" => 15221122, ), 1 => array ( "id" => 4, "uid" => 10001, "href" => "111222", "path" => "static/img/0.jpg", "number" => 0, "create_at" => 222222, ), ), "likebar" => array ( 0 => array ( "href" => "111222", "uid" => "10002", ), "hot" => 1, "comments" => 1, "status" => false, ), "comments" => array ( 0 => array ( "id" => 4, "href" => "111222", "uid" => 10001, "comment" => "22222", "time" => 55241212, ), ), "userinfo" => array ( "uid" => 10002, "nickname" => "", "image" => "static/img/3.jpeg", ), "isFollow" => false, ), )[{"id":1,"uid":10001,"href":"111111","content":"\u54c8\u54c86666","create_at":1513264258,"user":{"id":1,"uid":10001,"email":"5414@qq.com","password":"111000","tel":null,"role":0,"created_at":null},"info":{"uid":10001,"nickname":"\u5c0f\u660e","image":"static\/img\/3.jpeg"},"pic":[{"id":1,"uid":10001,"href":"111111","path":"static\/img\/0.jpg","number":0,"create_at":1513264258},{"id":2,"uid":10001,"href":"111111","path":"static\/img\/1.jpg","number":0,"create_at":1521442222},{"id":5,"uid":10001,"href":"111111","path":"static\/img\/0.jpg","number":0,"create_at":22222}],"likebar":{"0":{"href":"111111","uid":"10001"},"1":{"href":"111111","uid":"10001"},"hot":2,"comments":3,"status":true},"comments":[{"id":1,"href":"111111","uid":10001,"comment":"hahhahah","time":14751452},{"id":2,"href":"111111","uid":10001,"comment":"666","time":14521415},{"id":3,"href":"111111","uid":10002,"comment":"ffffff","time":1522441}],"userinfo":{"uid":10001,"nickname":"\u5c0f\u660e","image":"static\/img\/3.jpeg"},"isFollow":false},{"id":3,"uid":10001,"href":"111333","content":"55555","create_at":22542,"user":{"id":1,"uid":10001,"email":"5414@qq.com","password":"111000","tel":null,"role":0,"created_at":null},"info":{"uid":10001,"nickname":"\u5c0f\u660e","image":"static\/img\/3.jpeg"},"pic":[{"id":6,"uid":10001,"href":"111333","path":"static\/img\/0.jpg","number":0,"create_at":0}],"likebar":{"hot":0,"comments":0,"status":false},"comments":[],"userinfo":{"uid":10001,"nickname":"\u5c0f\u660e","image":"static\/img\/3.jpeg"},"isFollow":false},{"id":2,"uid":10002,"href":"111222","content":"fffffffff","create_at":211545220,"user":{"id":2,"uid":10002,"email":"5555@qq.com","password":"123123","tel":null,"role":0,"created_at":null},"info":{"uid":10002,"nickname":"\u5c0f\u534e","image":"static\/img\/3.jpeg"},"pic":[{"id":3,"uid":10001,"href":"111222","path":"static\/img\/0.jpg","number":0,"create_at":15221122},{"id":4,"uid":10001,"href":"111222","path":"static\/img\/0.jpg","number":0,"create_at":222222}],"likebar":{"0":{"href":"111222","uid":"10002"},"hot":1,"comments":1,"status":false},"comments":[{"id":4,"href":"111222","uid":10001,"comment":"22222","time":55241212}],"userinfo":{"uid":10002,"nickname":"\u5c0f\u534e","image":"static\/img\/3.jpeg"},"isFollow":false}]
Laravel
May.20,2022 


:


$res = [
        [
            'id' => 1,
            'uid' => 3,
            'pic' => [
                'id' => 2,
                'uid' => 33,
            ]
        ],
        [
            'id' => 11,
            'uid' => 31,
            'pic' => [
                'id' => 21,
                'uid' => 331,
            ]
        ],
    ];
    
foreach ($res as $key => $value) {
    $res[$key]['pic']['preview'] = uniqid();
}


 that's fine. 


 you have chosen the wrong object. Add a key-value pair to the pic array and traverse it once. In your way, the $v2 after the second traversal is the specific value in the pic array, but if you want to add the key-value pair to the pic array, it will not be successful 
.

 this has nothing to do with laravel, it's php array knowledge 


 I hope it will be helpful to you

Previous: The order of execution of setTimeout, nextTick, process.nextTick, etc. of vue

Next: Engineering project koa-bodyparser quotation report _ _ webpack_require__ (...) Is not a function

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3fade-34862.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3fade-34862.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?