读取嵌套 json 显示每个键值 [来自 mySQL]

Question

我正在尝试读取嵌套的 JSON 数据，其中键值是子嵌套的键和值，但它似乎不起作用。数据库表中的第一个 json 数据 [列：角色]

$json = array();

$sql = $db->query("SELECT * FROM u_info WHERE bid=".$branch);

while ($rs = $sql->fetch_assoc()) {    

    $rs['img'] = getImg($rs['img']);

    $query = $db->query('SELECT roles FROM wp_roles WHERE userid='.$rs['id'])->fetch_assoc();

    $rs['role'] = json_decode($query['roles']); // already a json format

    $json[] = $rs; 

}

exit(json_encode($json));// convert to json AJAX response works

然后json结果如下

{ 

    "academics":{ 

        "class":"true",

        "employee":"false",

        "students":"true",

        "subject":"false",

        "all":"true"

    },

    "exam":{ 

        "exams":"false",

        "schedule":"false",

        "result":"false",

        "marksheet":"false",

        "all":"false"

    },

    "timetable":{ 

        "class":"false",

        "teacher":"false",

        "all":"false"

    },

    "attendance":{ 

        "students":"true",

        "teacher":"true",

        "all":"true"

    }

}

未定义的 json 长度 [JAVASCRIPT]

// parse nested json 

var json = JSON.parse(data)

console.log(json.role) // works and print above json

console.log(json.role.length) // undefined

// for loop not works

for(i = 0; i < json.role.length; i++){

   for(y = 0; y < json.role[i].length; y++){

      // json.role.academics.class === true [if condition]

       if(json.role[i][y] === true){

         //......

       }

   }

}

Answer 1

上面的 JSON 是一个对象，这就是它的长度未定义的原因。您尝试读取数据的方式 - JSON 响应应该有一个通过“roles”属性引用的对象数组 - 以下格式应该可以工作。请检查回复。{&nbsp; &nbsp; "roles": [{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "academics": {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "class": "true",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "employee": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "students": "true",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "subject": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "all": "true"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; },&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "exam": {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "exams": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "schedule": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "result": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "marksheet": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "all": "false"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; },&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "timetable": {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "class": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "teacher": "false",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "all": "false"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; },&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "attendance": {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "students": "true",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "teacher": "true",&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "all": "true"&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; ]}