使用扫描将db值强制转换为特定类型

Question

I'm trying to read a UUID retrieved from Postgres, using github.com/jackc/pgx, into a variable of type uuid.UUID (From the github.com/google/uuid package).

An example code could be:

var dbId = uuid.UUID 
err = db.Pool.QueryRow("SELECT id FROM users WHERE objectname = $1;", objectUUID.String()).Scan(&dbId)
  if err != nil {
    log.Printf("Failed to fetch from database: %v", err)
    return
  }

The quickfix is to store the dbId in a temporary variable and then later convert said temporary variable into the correct type, but I have a feeling that there is a better, or more idiomatic, way to do it.

The error I'm getting is:

2018/02/12 07:09:18 handlers.go:187: Failed to fetch from database: can't scan into dest[1]: cannot assign &{[127 122 68 237 130 120 65 78 159 189 9 188 27 48 117 88] 2} into *uuid.UUID

Answer 1

The errors says that you are trying to Scan a struct pointer to the UUID pointer. The struct is defined here. So basically you should use this struct and Scan it into that and then convert the byte array in the struct to whatever UUID type you are using.