Method MigrateColumn

migrator/migrator.go:470–597

MigrateColumn migrate column

(value interface{}, field *schema.Field, columnType gorm.ColumnType)

// MigrateColumn migrate column
func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnType gorm.ColumnType) error {
	if field.IgnoreMigration {
		return nil
	}

	// found, smart migrate
	fullDataType := strings.TrimSpace(strings.ToLower(m.DB.Migrator().FullDataTypeOf(field).SQL))
	realDataType := strings.ToLower(columnType.DatabaseTypeName())
	var (
		alterColumn bool
		isSameType  = fullDataType == realDataType
	)

	if !field.PrimaryKey {
		// check type
		if !strings.HasPrefix(fullDataType, realDataType) {
			// check type aliases
			aliases := m.DB.Migrator().GetTypeAliases(realDataType)
			for _, alias := range aliases {
				if strings.HasPrefix(fullDataType, alias) {
					isSameType = true
					break
				}
			}

			if !isSameType {
				alterColumn = true
			}
		}
	}

	if !isSameType {
		// check size
		if length, ok := columnType.Length(); length != int64(field.Size) {
			if length > 0 && field.Size > 0 {
				alterColumn = true
			} else {
				// has size in data type and not equal
				// Since the following code is frequently called in the for loop, reg optimization is needed here
				matches2 := regFullDataType.FindAllStringSubmatch(fullDataType, -1)
				if !field.PrimaryKey &&
					(len(matches2) == 1 && matches2[0][1] != fmt.Sprint(length) && ok) {
					alterColumn = true
				}
			}
		}
	}

	// check precision
	if realDataType == "decimal" || realDataType == "numeric" &&
		regexp.MustCompile(realDataType+`\(.*\)`).FindString(fullDataType) != "" { // if realDataType has no precision,ignore
		precision, scale, ok := columnType.DecimalSize()
		if ok {
			if !strings.HasPrefix(fullDataType, fmt.Sprintf("%s(%d,%d)", realDataType, precision, scale)) &&
				!strings.HasPrefix(fullDataType, fmt.Sprintf("%s(%d)", realDataType, precision)) {
				alterColumn = true
			}
		}