How can I change the text of a cell with data defined in ColumnDef?

angelo.rendon

I have a datatable with 5 columns. The last column is the only one that I have defined in columnDef because it will always start with the content: [ + ], indicating you can click it to expand. Once clicked and expanded, i want it to change to: [ - ]. I first tired defining the content by defaultContent, but I couldnt not obtain that data to edit. I then tried doing:

"columnDefs": [ {
                    "targets": 5,
                    "className": '',
                    "data": function ( data, type, full, meta ) {
                       return '<span><a>[ + ]</a></span>';
                    }
                }, 

By doing this, I can see the data by outputting,

data = table.cell(row,5).data();
console.log("DATA:::::: " + data);

But for some reason I cannot change the cell data by doing:

table.cell(row,5).data('<span><a>[ - ]</a></span>').draw();

Why is this? What would be a good way to change the text on click? I by doing the method above, I am able to change all the other fields on click but not the columnDef generated data.
Note: The other data is populated by javascript data ( [ [stuff, stuff,] , [stiff, stuff] ])

Thanks!