demo: strange XORM or DB bug

[wxiaoguang]

These 2 code blocks are exactly the same, but the one in TestEmptyRepoAddFile fails to update database, the xorm.exec function only generates about 8-9 columns in the SQL (no is_empty column)

[wxiaoguang]

@lunny

[lunny]

If there are no Cols("is_empty", "default_branch"), XORM will generate update columns automatically. Since there is no real zero value for bool type, is_empty will not be generated. Only non-empty strings, non-zero integers and non-nil pointers will be considered as columns needs to be updated.

[lunny]

Suggested change

	_, err := db.GetEngine(db.DefaultContext).ID(user30EmptyRepo.ID).Update(user30EmptyRepo)
	_, err := db.GetEngine(db.DefaultContext).ID(user30EmptyRepo.ID).Cols("is_empty", "default_branch").Update(user30EmptyRepo)

[lunny]

Suggested change

	_, err := db.GetEngine(db.DefaultContext).ID(user30EmptyRepo.ID).Update(user30EmptyRepo)
	_, err := db.GetEngine(db.DefaultContext).ID(user30EmptyRepo.ID).Cols("is_empty", "default_branch").Update(user30EmptyRepo)

[wxiaoguang]

If there are no Cols("is_empty", "default_branch"), XORM will generate update columns automatically. Since there is no real zero value for bool type, is_empty will not be generated. Only non-empty strings, non-zero integers and non-nil pointers will be considered as columns needs to be updated.

But true is non-zero value.

[lunny]

If there are no Cols("is_empty", "default_branch"), XORM will generate update columns automatically. Since there is no real zero value for bool type, is_empty will not be generated. Only non-empty strings, non-zero integers and non-nil pointers will be considered as columns needs to be updated.

But true is non-zero value.

It's something right. It's also weird if true can be updated but false cannot be. So the decision at that time is boolean will not be generated automatically at any time.