`:many` query returns `nil` slice on empty result

[gnuletik]

Version

1.13.0

What happened?

When executing a :many query that returns an empty slice, the returned slice is nil.

e.g.
With this query,

-- name: GetItems :many
SELECT * FROM items;

The following code is generated

func (q *Queries) GetItems(ctx context.Context) ([]*Item, error) {
	rows, err := q.db.Query(ctx, getItems)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var items []*Item
	for rows.Next() {
		var i Item
		if err := rows.Scan(
			&i.ID,
		); err != nil {
			return nil, err
		}
		items = append(items, &i)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	return items, nil
}

func main() {
  items, err := db.GetItems(context.Background())
  fmt.Println("items is nil: ", items == nil) // true
  fmt.Println("err is nil: ", err == nil) // true
}

IMO, an empty array should be returned instead of nil.

For the usecase, it can be an issue when you want to serialize items as JSON because it gets serialized as null instead of an empty array ([]).

As a fix, it's possible to change the following line in the generated function:

- 	var items []*Item
+	items := []*Item{}

I can open a PR if that sounds good to you.

Thanks!

Relevant log output

No response

Database schema

No response

SQL queries

No response

Configuration

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Playground URL

No response

What operating system are you using?

No response

What database engines are you using?

No response

What type of code are you generating?

No response

[kyleconroy]

You can change this behavior by setting emit_empty_slices to true.

emit_empty_slices:
    If true, slices returned by :many queries will be empty instead of nil. Defaults to false.

[gnuletik]

Thanks for the fast answer @kyleconroy! Sorry, I missed that but it does exactly what I need.
Thanks for this great library also!