Field Filtering

When creating or updating data using struct data, especially during updates, some fields may not need updating. Therefore, corresponding fields should not be assigned values. For example:

type Book struct {
    Id      uint
    Name    string
    Author  string
    Price   float64
    PubTime *gtime.Time `orm:"publish_time"`
}

data := Book{
    Name:    "Linux驱动开发入门与实践",
    PubTime: gtime.New("2023-10-11"),
}

_, err = dao.Book.Ctx(ctx).Where("id", 13).Data(data).Update()

Updating like this would update id, author, and price to their respective zero values: 0, "", 0.

To solve this issue, there are several solutions:

Specify Fields to Update Using Fields

dao.Book.Ctx(ctx).Fields("name", "publish_time").Where("id", 13).Data(data).Update()

Exclude Fields Not to Update Using FieldsEx

dao.Book.Ctx(ctx).FieldsEx("id,author,price").Where("id", 13).Data(data).Update()

Filter Empty Values Using OmitEmpty

data := Book{
    Name:    "Linux驱动开发入门与实践",
    Price:   0,
    PubTime: nil,
}
dao.Book.Ctx(ctx).Where("id", 13).OmitEmpty().Data(data).Update()

With this method, values like 0 and nil will be ignored and not updated.

Using do Object for Field Filtering

When using gf gen dao, each table generates a corresponding do object. Using the do object as a parameter automatically filters empty values.

data := do.Book{
    Name:        "Linux驱动开发入门与实践",
    Price:       0,
    PublishTime: nil,
}

dao.Book.Ctx(ctx).Where("id", 13).Data(data).Update()

Using this approach, non-nil zero values can also be updated.

The do object can also be used to pass query conditions, automatically filtering empty values:

where := do.Book{
    Author:      "郑强",
    Id:          13,
    PublishTime: nil,
}

books, err := dao.Book.Ctx(ctx).Where(where).All()
// Equivalent to
books, err := dao.Book.Ctx(ctx).Where("id", 13).Where("author", "郑强").All()