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A text in JSON format is given in the form of a string, and Queries is given consisting of key of given JSON object in the form of a string. For each query, value of that key is to be printed.

JSONtext = `{"Student":{"Name":"John","Age":"15"},"Class":"10"}`;
NoOfQueries=3;
queries=["Student.Name","Student.Age", "Class"];

ansShouldBe = John 15 10

queries[0] = ("Student.Name") ans should be calculated ans = myobj.Student.Name is "John", similarly for 2nd is 15 & 3rd is 10

I have written just the beginning of the code, can someone help me to complete this?

function jsonfn(text,N,queries){
    let myObj = JSON.parse(text);
    for(let i=0; i<queries.length ; i++)
    {
        let query = queries[i]; //student.name
        console.log(myObj.query) //this is giving undefined
        // please complete this code
    }

}

If I run myObj.Student.Nameit gives ans as "John" but how to do it dynamically if Student.Name is given in a string provided by user. How to parse Json object at run time? is there a way we can do it

The object can also be deeply nested like

{
    "c": {
        "mf": {
            "he": "k"
        }
    },
    "p": "q"
}

Same with the queries ["c.mf.he", "p"]

Please someone help me on this.

Michael M.
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anmol arora
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2 Answers2

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You can't use directly the array values in the object (like this: obj.array_values), they both have different types.

Try this one! It works fine.

function jsonfn(text, queries){
    let myObj = JSON.parse(text);
    for(let i = 0; i< queries.length ; i++)
    {
        let query = queries[i];
        if (Array.isArray(query)) {
          console.log(myObj[query[0]][query[1]]);
        }
        else {
          console.log(myObj[query]);
        }
    }
}

let JSONtext = `{"Student":{"Name":"John","Age":15},"Class":10}`;
let queries=[["Student", "Name"], ["Student", "Age"], "Class"];

jsonfn(JSONtext, queries)
siddharth rastogi
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  • Thanks @Siddhart_Rastogi, it was very helpful. I had to change a little bit of it for nested objects. Thanks a ton! – anmol arora Sep 29 '22 at 09:08
0

Thanks @siddharthRastogi I just changed your ans a bit, and got this! 

let JSONtext = `{
    "Student": {
        "Name": "John",
        "Age": "15"
    },
    "Class": "10",
    "Address": {
        "Country": {
            "State": {
                "City": {
                    "location": "12, abc road",
                    "pincode": "987654"
                }
            }
        }
    }
}`;
let queries=["Student.Name","Student.Age", "Class" , "Address.Country.State.City.location","Address.Country.State.City.pincode"];
queries = changeQueryArr(queries);

Added a function to changeQueryArr() to convert queries into dot splitted queries for deeply nested objects.

function changeQueryArr(queries)
{
    let ans = []
    for(let i=0;i<queries.length;i++)
    {
        let str = queries[i];
        ans.push(str.split("."));
    }
    return ans;
}
now queries would look like 

// queries=[["Student", "Name"], ["Student", "Age"], "Class",["Address","Country","State","City","location"],["Address","Country","State","City","pincode"]];



function jsonfn(text, queries){
    let myObj = JSON.parse(text);
    for(let i = 0; i< queries.length ; i++)
    {
        let query = queries[i];
        if (Array.isArray(query)) {
            console.log( query.reduce((prev, curr) => prev?.[curr], myObj))
        }
        else {
          console.log(myObj[query]);
        }
    }
}


jsonfn(JSONtext, queries)


// Ans :- 
// John
// 15
// 10
// 12, abc road
// 987654
anmol arora
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