遍历多维Json

Question

I have a multilevel JSon and need to loop through and get its column name and value.

 var json   {  
       "Students":[  
          {  
             "name":{  
                "value":"Allan"
             },
             "number":{  
                "value":"123"
             }
          },
          {  
             "name":{  
                "value":"Frank"
             },
             "number":{  
                "value":"456"
             }
          }
       ]
    }

I can loop through and get the column name but cannot get the value.

var objectKeys = Object.keys(json); 
for (var key in objectKeys)
    {       
        var student = json.Students;

        for (var i = 0; i < student .length; i++) {

            for (var column in json.Students[i])
                {

                window.print(column);
                window.print(column.value);                                         

            }

        }       
}

The above gives me the following

name
undefined
number
undefined
name
undefined
number
undefined

Ideally i want to treat one row separately so i can insert it in database, like insert Allan and 123 against name and number column of students table.

Answer 1

var objectKeys = Object.keys(json);
for (var key in objectKeys)
{       
    var student = json.Students;

    for (var i = 0; i < student .length; i++) {

        for (var column in json.Students[i]) {
            window.print(column);
            window.print(json.Students[i][column].value);

        }

    }
}

since key in outer for loop isn't used it is redundant

Answer 2

var objectKeys = Object.keys(json); 
for (var key in objectKeys) {       
    var student = json.Students;
    for (var i = 0; i < student .length; i++) {
        window.print(json.Students[i].name.value);
        window.print(json.Students[i].number.value);

    }       
}

Answer 3

Your JSON object contains 1 entry with key Students and value of a list of 2 dictionaries.

so var objectKeys = Object.keys(json); represents just one value "Students"

It doesn't look like you're using the var key in objectKeys as you instantiate this variable key but never use it.

Re-write your code like this if your intent is to loop through the dictionary:

 var json   {  
       "Students":[  
          {  
             "name":{  
                "value":"Allan"
             },
             "number":{  
                "value":"123"
             }
          },
          {  
             "name":{  
                "value":"Frank"
             },
             "number":{  
                "value":"456"
             }
          }
       ]
    }

for(let i = 0; i < json["Students"].length; i++){

    let key_values = Object.keys(json["Students"][i]);

    for(let inner_key_values in key_values){
        window.print(json["Students"][i][inner_key_values].value);
    }

}

Answer 4

I wrote the below snippet for you - It prints a nested object recursively. You can modify it as you want.

var p = {
    "p1": "value1",
    "p2": "value2",
    "p3": "value3",
    "p4": {
        "p4": 'value 4'
    }
};



/**
*   Printing a nested javascript object
*/
function jsonPrinter(obj) {

    for (let key in obj) {
        // checking if it's nested
        if (obj.hasOwnProperty(key) && (typeof obj[key] === "object")) {
            jsonPrinter(obj[key])
        } else {
            // printing the flat attributes
            console.log(key + " -> " + obj[key]);
        }
    }
}

jsonPrinter(p);