DataTables

The callback function fnRender() overwrite the original values, as described in the post "fnRender overwrites the original value" at http://www.datatables.net/forums/discussion/183/fnrender-overwrites-the-original-value/p1. The solution to have a hidden title does not solve my situation:

Some cells use the data from other cells in the same row. Let me give an example: We have affiliates having sales and commissions. The next two columns are calculated from the sales and the commission. At the moment, the server must send this data:

    // Affiliate Name, Sales, Commission, % Commission, Net, Date of Last Sale
    [ "Dan", 1000000, 400000, .4, 600000 ],
    [ "Jim", 20000, 5000, .25, 15000 ],
    [ "Smith", 80000, 40000, .5, 40000 ],
    [ "Bart", 100000, 99000, .99, 1000 ]

The ideal data from the server would be:

    [ "Dan", 1000000, 400000 ],
    [ "Jim", 20000, 5000 ],
    [ "Smith", 80000, 40000 ],
    [ "Bart", 100000, 99000 ]

When I format a number such as 1000000 using fnRender() to be displayed as "$1,000,000", I cannot longer use fnRender() to calculate the % Commission because the the string "$1,000,000" is not a number anymore.

One solution would be to have a callback method named fnRowDataCallback(iRow, aDataOriginal, aDataRow)

The table would call this method just after processing the aaData or after receiving data from sAjaxSource. After calling fnRowDataCallback(), the content of aDataOriginal would be discarded. The callback function fnRowDataCallback() would allow the developer to perform calculations, and even re-order the columns by assigning aDataRow. This would bring a tremendous help because it is much easier to change the HTML page than changing the routine on the server fetching the data.

Example of swapping two columns:
aDataRow[0] = aDataOriginal[1];
aDataRow[1] = aDataOriginal[0];

In the example above, the code for fnRowDataCallback() would look like this:

function fnRowDataCallback(iRow, aDataOriginal, aDataRow)
	{
	aDataRow[0] = aDataOriginal[0]; // Affiliate Name
	aDataRow[1] = aDataOriginal[1]; // Sales
	aDataRow[2] = aDataOriginal[2]; // Commission
	aDataRow[3] = aDataOriginal[2] / aDataOriginal[1]; // % Commission
	aDataRow[4] = aDataOriginal[1] - aDataOriginal[2]; // Net
	}

Also, as webmasters, we want to see how displaying the data in a different way would look better. Therefore, a variant could be to display the "% Profit" rather than the "% Commission". Having fnRowDataCallback(), it the code would be as easy as replacing two lines of code:

function fnRowDataCallback(iRow, aDataOriginal, aDataRow)
	{
	aDataRow[0] = aDataOriginal[0]; // Affiliate Name
	aDataRow[1] = aDataOriginal[1]; // Sales
	aDataRow[2] = aDataOriginal[2]; // Commission
	aDataRow[3] = aDataOriginal[1] - aDataOriginal[2]; // Net
	aDataRow[4] = aDataRow[3] / aDataOriginal[1]; // % Profit
	}

Another feature request would be to specify the 'display', 'sort' and 'filter' in fnRowDataCallback()

function fnRowDataCallback(iRow, aDataOriginal, aDataRow)
	{
	aDataRow[0] = aDataOriginal[0]; // Affiliate Name
	
	aDataRow[1] = aDataOriginal[1]; // Sales
	aDataRow[1].display = "$" + FormatAmount(aDataOriginal[1]); // Display a "$" in front of the sales and add 1000 separators
	aDataRow[1].filter = aDataRow[1] + " " + aDataRow[1].display;   // Filter using either the raw value or the formatted value
	}

If the aDataRow[].sort is not specified, then the value from aDataRow[] is used. The same can be done for aDataRow[].display and aDataRow[].filter.