CODEWITHSUNDEEP
postgresqlgomux
als9xd
als9xd

Reputation: 854

Go optional fields with SQLX

I'm learning Go and am trying to create an api endpoint that has an 'fields' parameter. When I try to scan the sqlx resulting rows it into a struct,however the fields omitted by the user are being returned as as an empty string. Is there a way that I can change the struct to reflect only the fields that the user passed? I don't think I want to use omitempty in case for example user_name is an empty string.

type User struct {
    Id int `db:"id"`
    UserName string `db:"user_name"`
}


func GetUsers(w http.ResponseWriter,r *http.Request,db *sqlx.DB) {
    acceptedFields := map[string]bool {
        "id":true,
        "user_name":true,
    }
    var requestedFields string = "id"
    if r.URL.Query().Get("fields") != ""{
        requestedFields = r.URL.Query().Get("fields");
    }

    for _, requestedField := range strings.Split(requestedFields,",") {
        if !acceptedFields[requestedField] {
            http.Error(w, fmt.Sprintf("Unknown Field '%s'",requestedField), http.StatusBadRequest)
        }
    }

    users := []User{}

    err := db.Select(&users,fmt.Sprintf("SELECT %s FROM users",requestedFields)); 
    if err != nil {
        log.Fatal(err)
    }
    response, _ := json.Marshal(users)
    fmt.Fprintf(w,string(response))
}

Resulting Endpoint Output

/users?fields=id => [{"Id":12,"UserName":""}]

Desired Endpoint Output

/users?fields=id => [{"Id":12}]

Also using sql.NullString results in this:

[{"Id":12,"UserName":{"String":"","Valid":false}}]

Upvotes: 1

Views: 2966

Answers (1)

als9xd
als9xd

Reputation: 854

Thanks to mkorpriva here is a solution

type User struct {
    Id int `db:"id"`
    UserName *string `db:"user_name" json:",omitempty"`
}

Upvotes: 2

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