func (d *Page) GetDataSize() int {
	return len(d.GetData())
}
GetDataSize will return the size of data.
it's len(GetData())
package gxpage
type Page struct {
	requestOffset int
	pageSize      int
	totalSize     int
	data          []interface{}
	totalPages    int
	hasNext       bool
}
func (d *Page) GetOffset() int {
	return d.requestOffset
}
func (d *Page) GetPageSize() int {
	return d.pageSize
}
func (d *Page) GetTotalPages() int {
	return d.totalPages
}
func (d *Page) GetData() []interface{} {
	return d.data
}