BlackListing or WhiteListing columns for struct based inserts and updates

[derkan]

This PR is to blacklist or whitelist columns during struct based inserts or updates. For example:

type User struct {
	ID             int64            `db:"id,key,auto" json:"id"`
	Username       string           `db:"username" json:"username"`
	LastLoginIP    types.NullString `db:"last_login_ip" json:"last_login_ip" `
	LastLoginTime  types.NullTime   `db:"last_login_time" json:"last_login_time"`
	CreatedAt      time.Time        `db:"created_at,auto" json:"created_at"`
	UpdatedAt      types.NullTime   `db:"updated_at" json:"updated_at"`
}

func insert(db *godb.DB, res *User) error {
     return db.Insert(res).Blacklist("last_login_ip", "last_login_time", "updated_at").Do()
}

func update(db *godb.DB, res *User) error {
     return db.Update(res).Blacklist("last_login_ip", "last_login_time", "created_at").Do()
}

func login(db *godb.DB, res *User) error {
     return db.Update(res).Whitelist("last_login_time", "last_login_ip").Do()
}

Also added BlacklistReset or WhitelistReset for struct based inserts or updates to clear lists.

[lozaeric]

nice feature!

[samonzeweb]

wbColsSet need to be set to true here.

You can add a test with BulkInsert to reveal the error (and ensure there will be no regression) :

			Convey("Do executes the query using a blacklist", func() {
				dummies := make([]Dummy, 0, 2)
				dummy1 := Dummy{
					AText:           "Dummy1",
					AnotherText:     "Foo",
					AnInteger:       12345,
					ANullableString: sql.NullString{String: "Void", Valid: true},
				}
				dummy2 := Dummy{
					AText:           "Dummy2",
					AnotherText:     "Foo",
					AnInteger:       12345,
					ANullableString: sql.NullString{String: "Void", Valid: true},
				}
				dummies = append(dummies, dummy1, dummy2)
				err := db.BulkInsert(&dummies).Blacklist("a_nullable_string").Do()
				So(err, ShouldBeNil)
			})

[derkan]

That's right, it is a footprint of my struggle to preserve to match params and values. First tried a map for columns and values, that failed because of random ordering of maps. Later used slices for columns and values.
Corrected. Thanks

[samonzeweb]

As you made some more changes since my last review, I'm not sure if it's finished or not (Github lack the WIP status in PR).

Can I merge it ?

[derkan]

Yes please!