The spouse and the children can come to Canada if they come from a country where a visitor visa is required. They can apply for a visitor visa.
If foreign nationals were to be automatically given the right to enter and study in Canada before any examination of the bona fides of the marriage, for example, we could certainly expect there to be some abuse in connection with that program. However, the department gives priority processing to applications to sponsor the spouses and children of Canadian citizens as permanent residents.