Get postgresql array into struct with StructScan

Question

Test data:

CREATE TABLE test (id int, data text[])
INSERT INTO test(id, data) VALUES(1, '{a,b,c}')

Go Code. First - one that is working just fine:

func main() {
  db, _ := sqlx.Open("postgres", "user=postgres dbname=test sslmode=disable")
  var id int
  var asSlice []string
  err := db.QueryRowx(`SELECT id, data FROM test WHERE data @> ARRAY['b']`).Scan(&id, pq.Array(&asSlice))
  if err != nil {
    log.Fatal(err)
  }
  fmt.Println(id, asSlice)
}

I get 1 [a b c] as expected. But here I manually assign results to the variables

Now, to the part that is not working - using StructScan

type MyStruct struct {
    Id   int
    Data []string
}

func main() {
    db, _ := sqlx.Open("postgres", "user=postgres dbname=test sslmode=disable")
    var testStruct MyStruct
    err := db.QueryRowx(`SELECT id, data FROM test WHERE data @> ARRAY['b']`).StructScan(&testStruct)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(testStruct)
}

sql: Scan error on column index 1: unsupported Scan, storing driver.Value type []uint8 into type *[]string

I guess that means that sqlx does not know about PostgreSQL arrays and does not use pq.Array internally.

What should I do about it? Maybe I am doing something wrong? Or maybe I should apply pq.Array manually? If so - how?

@Melvin "expected struct but got slice". I'am querying only one row. So it is not it. — Davinel
– Davinel, Commented Jun 6, 2017 at 2:08

Melvin · Accepted Answer · 2017-06-06 09:05:51Z

22

Try using pq.StringArray type for []string

type MyStruct struct {
    Id   int
    Data pq.StringArray
}

answered Jun 6, 2017 at 9:05

Melvin

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