FIX #7427 Optimistic Lock in BeforeUpdate: PK Condition Placement Affecting DB Plan Efficiency

[ZhengweiHou]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

FIX #7427 :Optimistic Lock in BeforeUpdate: PK Condition Placement Affecting DB Plan Efficiency

User Case Description

type Hzw struct {
	Id      int32  `gorm:"column:ID;primarykey"`
	Type    int32  `gorm:"column:TYPE;primarykey"`
	Name    string `gorm:"column:NAME;size:100;not null"`
	Version int32  `gorm:"column:VERSION;default:0"`
}

func (h *Hzw) BeforeUpdate(tx *gorm.DB) (err error) {
	cv := h.Version
	h.Version++
	nExprs := tx.Statement.BuildCondition("VERSION", cv)
	newwhere := clause.Where{Exprs: nExprs}
	tx.Statement.AddClause(newwhere)
	return nil
}

func TestUpdateHookOptimisticLock(t *testing.T) {
	hzw := &Hzw{
		Id:      1,
		Type:    2,
		Name:    "hzw",
		Version: 0,
	}

	statement := DB.Session(&gorm.Session{DryRun: true}).Save(hzw).Statement
	sqlstr := statement.SQL.String()

	// Find the WHERE clause
	whereIndex := strings.Index(strings.ToUpper(sqlstr), "WHERE")
	if whereIndex == -1 {
		t.Errorf("No WHERE clause found in the SQL statement")
		return
	}
	whereClause := sqlstr[whereIndex+len("WHERE"):]

	// Define the expected order of conditions
	expectedOrder := []string{"ID", "TYPE", "VERSION"}

	// Use regular expression to match column names
	re := regexp.MustCompile(`\b(?:ID|TYPE|VERSION)\b`)
	matches := re.FindAllString(whereClause, -1)

	if len(matches) < len(expectedOrder) {
		t.Errorf("The actual number of WHERE conditions is less than the expected number")
		return
	}

	for i, expected := range expectedOrder {
		if strings.ToUpper(matches[i]) != expected {
			t.Errorf("The order of WHERE conditions is incorrect. Expected %s at position %d, but got %s", expected, i+1, matches[i])
			return
		}
	}

	vars := statement.Vars
	cversion := vars[4]
	vversion := vars[1]
	if cversion != int32(0) {
		t.Fatalf("current VERSION should be 0")
	}
	if vversion != int32(1) {
		t.Fatalf("value VERSION should be 1")
	}
}