fnupdate updates wrong row datatables - datatables

Question

I am trying to update a row by passing index.
http://live.datatables.net/raculubo/1/
But it most of the time replaces a wrong row.
The code is :-
$(document).ready(function() {
var table = $('#example').DataTable();
var index = table.column(0).data().indexOf("Cedric Kelly");
console.log("index2",index);
table.row().data(["ax","by","dd"], index);
} );

Answer 1

This is happening because of how you are sorting your data, leading to a difference between the "sort order" index and the "internal DataTables" index.
The table.column(0).data() function will return an array of names, as currently displayed in the table, taking into account sorting. In this scenario, the index of "Cedric Kelly" is therefore 1.
However, the internal unique index value stored by DataTables is actually 3 because that is the order provided to DataTables from your HTML code when the data was loaded for the very first time (where Cedric Kelly is the 4th record listed - so the index is 3).
This initial loading happens before data is sorted, and it is during this step that data indexes are assigned. Once assigned, they never change (unless you delete data).
Your data update function uses the value of 1 - thus updating the wrong row.
The fix for this is to tell DataTables to use the original loading order in the table.column(0).data() function:
var index = table.column(0, {order:'index'} ).data().indexOf("Cedric Kelly");
That directive {order:'index'} causes DataTables to use the original loading order. Now, the correct record will be updated because this index will now return 3 instead of 1.
You can see more details about this "selector modifier" syntax here.
Bear in mind that the correct syntax for updating a row is actually this:
table.row( index ).data(["ax","by","dd"]);
Finally, bear in mind that if you filter your data, then you are OK, since the default value used is search: 'none' - which means "do not take searching/filtering into account" when selecting the column data.