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Index -1 for json key – Jquery ajax

I have been searching for answers to this for awhile and can’t seem to see the obvious.

I’m attempting to return the value by index of a json string. Although the key appears to match, its returning -1 for index. I simply want the value, in this case “Ethan” for key username. I’ve verified that rows is valid json.

for (var r in rows) {
            table_body += '<tr>';
            for (var c in cols) {

                table_body += '<td>';
                //table_body += Object.keys(rows[r]);
                var idx = c;
                console.log(rows[r]);
                var o = rows[r]; //the object
                //var key = Object.keys(o)[idx];

                var key = cols[c].title;
                var index = Object.keys(cols).indexOf(key);
                console.log('key: '+key);
                console.log('index: ' + index);
                console.log('cols: ');
                console.log(cols[c]);
                console.log('c: ' + c);
                var value = o[index];
                table_body += value;
                table_body += '</td>';
            }
            table_body += '</tr>';
        }
        table_body += '</table>';

This is the output in the console showing “o”, which is the json, the key, which is username, and the index of that key, -1

enter image description here

EDIT added more logs…enter image description here

EDIT
This is the json for rows…

[{"id":136,"userName":"ethan","halfDays":1,"fullDays":11,"approvedDept":null,"approvedExec":true,"type":"vacation","createDate":"/Date(1332863557393)/","approvedDeptDate":null,"approvedExecDate":null,"leaveBegin":"/Date(1311570000000)/","leaveEnd":"/Date(1311570000000)/","notes":"Beginning Balance","overage":false,"department":null,"reminderSent":true},{"id":381,"userName":"ethan","halfDays":0,"fullDays":1,"approvedDept":null,"approvedExec":true,"type":"sick","createDate":"/Date(1336055792800)/","approvedDeptDate":null,"approvedExecDate":"/Date(1336021200000)/","leaveBegin":"/Date(1335502800000)/","leaveEnd":"/Date(1335502800000)/","notes":null,"overage":false,"department":"Marketing","reminderSent":true}]

and cols…

[{ "title":"userName" },{ "title":"leaveBegin" },{ "title":"leaveEnd" }]
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3

Answers


  1. 0

    It looks like, you want to find index in array of objects. Use findIndex:

    let cols = [{ "title":"userName" },{ "title":"leaveBegin" },{ "title":"leaveEnd" }];
let index = cols.findIndex(col => col.title == "leaveBegin");
console.log(index);
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  2. 0

    cols is an array of objects, Object.keys() just returns an array of the array indexes, not the values of the title properties of the objects.

    Use findIndex() to search for a matching object.

    var index = cols.findIndex(obj => obj.title == key)

    Alternatively, before the loops you could create an object that maps all the keys to their indexes, and use that.

    var indexes = {};
cols.forEach(({title}, index) => indexes[title] = index);

    Then in the loop you would do

    var index = key in indexes ? indexes[key] : -1;
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  3. 0

    To get the corresponding value to some field, consider the simpler example involving a dumb row:

    const row = { username: 'a', leaveBegin: 'b', leaveEnd: 'c'}

    consider the col: 

    const col = {title: 'username'}

    you would get the value associated to username with

    row[col.title] //'a'

    now the array cols:

    const cols = [{ "title":"userName" },{ "title":"leaveBegin" },{ "title":"leaveEnd" }]
const values = cols.map(({ title }) => row[title]) // ['a', 'b', 'c']

    Finally for each row:

    const rows = [{"id":136,"userName":"ethan","halfDays":1,"fullDays":11,"approvedDept":null,"approvedExec":true,"type":"vacation","createDate":"/Date(1332863557393)/","approvedDeptDate":null,"approvedExecDate":null,"leaveBegin":"/Date(1311570000000)/","leaveEnd":"/Date(1311570000000)/","notes":"Beginning Balance","overage":false,"department":null,"reminderSent":true},{"id":381,"userName":"ethan2","halfDays":0,"fullDays":1,"approvedDept":null,"approvedExec":true,"type":"sick","createDate":"/Date(1336055792800)/","approvedDeptDate":null,"approvedExecDate":"/Date(1336021200000)/","leaveBegin":"/Date(1335502800001)/","leaveEnd":"/Date(1335502800002)/","notes":null,"overage":false,"department":"Marketing","reminderSent":true}]
const cols = [{ "title":"userName" },{ "title":"leaveBegin" },{ "title":"leaveEnd" }]
rows.forEach(row => {
  cols.forEach(({ title }) => {
    console.log(title, row[title])
  })
})
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