GO - parse mysql json to array of strings-CodePudding

There is such struct:

Programs struct {
    ID                  int      `json:"id"`
    ShortName           string   `json:"short_name"`
    ProgramPoints       float64  `json:"program_points"`
    Countries           []string `json:"countries"`
}

The column countries is JSON column which contains array of countries ["US","GB"] Parsing:

    stmt, err := db.Query(sql)
    err = stmt.Scan(
            &program.ID,
            &program.ShortName,
            &program.ProgramPoints,
            &program.Countries)

Has error unsupported Scan, storing driver.Value type []uint8 into type *[]string I've found the way how to parse JSON object to struct but not array. Thx in advance for any help

CodePudding user response：

So seeing as you're wanting the JSON value to come from the DB and be (un)marshaled automagically, you'll need to create a type for that:

type Programs struct {
    ID                  int       `json:"id"`
    ShortName           string    `json:"short_name"`
    ProgramPoints       float64   `json:"program_points"`
    Countries           Countries `json:"countries"`
}

type Countries []string

func (c Countries) Value() (driver.Value, error) {
    return json.Marshal(c) // return json marshalled value
}

func (c *Countries) Scan(v interface{}) error {
    switch tv := v.(type) {
    case []byte:
        return json.Unmarshal(tv, &c) // unmarshal
    case []uint8:
        return json.Unmarshal([]byte(tv), &c) // can't remember the specifics, but this may be needed
    }
    return errors.New("unsupported type")
}

That should handle the stmt.Scan stuff