getRow method
Called to obtain the data about a particular row.
The new DataRow.byIndex constructor provides a convenient way to construct DataRow objects for this callback's purposes without having to worry about independently keying each row.
If the given index does not correspond to a row, or if no data is yet available for a row, then return null. The row will be left blank and a loading indicator will be displayed over the table. Once data is available or once it is firmly established that the row index in question is beyond the end of the table, call notifyListeners.
Data returned from this method must be consistent for the lifetime of the object. If the row count changes, then a new delegate must be provided.
Implementation
DataRow getRow(int index);