GORM——Mysql

定义的默认类型

gorm.Model
GORM 定义一个 gorm.Model 结构体，其包括字段 ID、CreatedAt、UpdatedAt、DeletedAt
// gorm.Model 的定义
type Model struct {
  ID        uint           `gorm:"primaryKey"`
  CreatedAt time.Time
  UpdatedAt time.Time
  DeletedAt gorm.DeletedAt `gorm:"index"`
}

数据类型默认配置

func (dialector Dialector) DataTypeOf(field *schema.Field) string {
    switch field.DataType {
    case schema.Bool:
        return "boolean"
    case schema.Int, schema.Uint:
        sqlType := "bigint"
        switch {
        case field.Size <= 8:
            sqlType = "tinyint"
        case field.Size <= 16:
            sqlType = "smallint"
        case field.Size <= 24:
            sqlType = "mediumint"
        case field.Size <= 32:
            sqlType = "int"
        }
        if field.DataType == schema.Uint {
            sqlType += " unsigned"
        }
        if field.AutoIncrement {
            sqlType += " AUTO_INCREMENT"
        }
        return sqlType
    case schema.Float:
        if field.Precision > 0 {
            return fmt.Sprintf("decimal(%d, %d)", field.Precision, field.Scale)
        }
        if field.Size <= 32 {
            return "float"
        }
        return "double"
    case schema.String:
        size := field.Size
        defaultSize := dialector.DefaultStringSize
        if size == 0 {
            if defaultSize > 0 {
                size = int(defaultSize)
            } else {
                hasIndex := field.TagSettings["INDEX"] != "" || field.TagSettings["UNIQUE"] != ""
                // TEXT, GEOMETRY or JSON column can't have a default value
                if field.PrimaryKey || field.HasDefaultValue || hasIndex {
                    size = 191 // utf8mb4
                }
            }
        }
        if size >= 65536 && size <= int(math.Pow(2, 24)) {
            return "mediumtext"
        } else if size > int(math.Pow(2, 24)) || size <= 0 {
            return "longtext"
        }
        return fmt.Sprintf("varchar(%d)", size)
    case schema.Time:
        precision := ""
        if !dialector.DisableDatetimePrecision {
            if field.Precision == 0 {
                field.Precision = 3
            }
            if field.Precision > 0 {
                precision = fmt.Sprintf("(%d)", field.Precision)
            }
        }
        if field.NotNull || field.PrimaryKey {
            return "datetime" + precision
        }
        return "datetime" + precision + " NULL"
    case schema.Bytes:
        if field.Size > 0 && field.Size < 65536 {
            return fmt.Sprintf("varbinary(%d)", field.Size)
        }
        if field.Size >= 65536 && field.Size <= int(math.Pow(2, 24)) {
            return "mediumblob"
        }
        return "longblob"
    }
    return string(field.DataType)
}

eg:

type Student struct {
    Id uint `gorm:"size:32;primaryKey;autoIncrement;not null"`
    Name string `gorm:"size:20"`
    Gender int `gorm:"size:4"`
    Number string `gorm:"type:char(8);uniqueIndex:uk_num"`
    DepartID uint `gorm:"size:32;not null;index:idx_dep"`
    MajorID uint `gorm:"size:32;not null;index:idx_major"`
    CreatedAt time.Time
    UpdatedAt time.Time
}

创建的数据表

CREATE TABLE `students` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(20) COLLATE utf8mb4_bin DEFAULT NULL,
  `gender` tinyint(4) DEFAULT NULL,
  `number` char(8) COLLATE utf8mb4_bin DEFAULT NULL,
  `depart_id` int(10) unsigned NOT NULL,
  `major_id` int(10) unsigned NOT NULL,
  `created_at` datetime(3) DEFAULT NULL,
  `updated_at` datetime(3) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uk_num` (`number`),
  KEY `idx_dep` (`depart_id`),
  KEY `idx_major` (`major_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;