扫描错误：不支持的扫描，存储驱动程序。将值类型<nil>转换为* string类型

Question

When I try to fetch Articles without photo from mysql database:

func ArticlesAllText() ([]Article, error) {
    var err error
    var result []Article
    err = database.SQL.Select(&result, "SELECT * FROM Article WHERE photo IS NULL")
    if err != nil {
        log.Println(err)
    }
    return result, standardizeError(err)
}

I get

sql: Scan error on column index 10: unsupported Scan, storing driver.Value type into type *string

When the field value is NULL.

How can I fix this?

Answer 1

Use sql.NullString.

https://godoc.org/database/sql#NullString

Personally, I hate this solution, which is why I normalize my DB so that there are no NULLs.

Either change

var result []Article

To

var result []sql.NullString

Then take those results and make a []Article using the checks from the documentation.

Or in your struct, change

Photo *string

To

Photo sql.NullString

And deal with the annoyance of it being a struct instead of a *string

Thanks to ATN, see here for a guide https://medium.com/aubergine-solutions/how-i-handled-null-possible-values-from-database-rows-in-golang-521fb0ee267