how to set cursor position at the end of the value in flutter in textfield?

I've been having the same problem with setting a TextEditingController and this is what worked for me.

controller.text = someString;
controller.selection = TextSelection.fromPosition(TextPosition(offset: controller.text.length));

TextSelection.fromPosition() does the following (from documentation):

Creates a collapsed selection at the given text position. A collapsed selection starts and ends at the same offset, which means it contains zero characters but instead serves as an insertion point in the text.