Postgres list parameter in Go (using database/sql and pq)

Question

I'm trying to write a query that takes a list parameter (ie, a single parameter which is a list of values). It appears that this is at least sometimes possible in Postgres (https://stackoverflow.com/a/10829760/836390). What I want is something like this:

rows, err := db.Query("SELECT * FROM table WHERE id in $1", []int{1, 2, 3})

However, when I execute this using the pq driver, I get an error:

sql: converting Exec argument #0's type: unsupported type []int, a slice

Is this simply not supported in pq yet, or is this not supported in database/sql, or not in Postgres at all, or what? Thanks!

Answer 1

You can use pq.Array with slice parameters nowadays. So the query would look like:

rows, err := db.Query("SELECT * FROM table WHERE id in $1", pq.Array([]int{1, 2, 3}))

Answer 2

So it looks like pq uses database/sql's default ValueConverter, which has no ability to handle slices (see the documentation for DefaultParameterConverter).

Answer 3

I couldn't get the accepted answer to work due to a syntax error. I modified the answer a bit and got it to work for me.

The resource I used was the pq.Array function documentation.

rows, err := db.Query("SELECT * FROM table WHERE id = ANY($1)", pq.Array([]int{1, 2, 3}))

Answer 4

Look at using an alternative Postgres client: https://github.com/vmihailenco/pg

The readme details array support and includes an example of using a slice.

    _, err := db.Query(users,
    `WITH users (name, emails) AS (VALUES (?, ?), (?, ?))
    SELECT * FROM users`,
    "admin", []string{"admin1@admin", "admin2@admin"},
    "root", []string{"root1@root", "root2@root"},
)

(I've not used this myself, but a look over it shows promise).

Answer 5

This does in fact appear to be 'temperamental'. Here are two I would attempt:

rows, err := db.Query("SELECT * FROM table WHERE id in ($1)", []int{1, 2, 3})

or

rows, err := db.Query("SELECT * FROM table WHERE id = ANY($1::[]int)", []int{1, 2, 3})