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package pgx_test
import (
"context"
"fmt"
"os"
"regexp"
"strconv"
"github.com/jackc/pgtype"
"github.com/jackc/pgx/v4"
)
var pointRegexp *regexp.Regexp = regexp.MustCompile(`^\((.*),(.*)\)$`)
// Point represents a point that may be null.
type Point struct {
X, Y float64 // Coordinates of point
Status pgtype.Status
}
func (dst *Point) Set(src interface{}) error {
return fmt.Errorf("cannot convert %v to Point", src)
}
func (dst *Point) Get() interface{} {
switch dst.Status {
case pgtype.Present:
return dst
case pgtype.Null:
return nil
default:
return dst.Status
}
}
func (src *Point) AssignTo(dst interface{}) error {
return fmt.Errorf("cannot assign %v to %T", src, dst)
}
func (dst *Point) DecodeText(ci *pgtype.ConnInfo, src []byte) error {
if src == nil {
*dst = Point{Status: pgtype.Null}
return nil
}
s := string(src)
match := pointRegexp.FindStringSubmatch(s)
if match == nil {
return fmt.Errorf("Received invalid point: %v", s)
}
x, err := strconv.ParseFloat(match[1], 64)
if err != nil {
return fmt.Errorf("Received invalid point: %v", s)
}
y, err := strconv.ParseFloat(match[2], 64)
if err != nil {
return fmt.Errorf("Received invalid point: %v", s)
}
*dst = Point{X: x, Y: y, Status: pgtype.Present}
return nil
}
func (src *Point) String() string {
if src.Status == pgtype.Null {
return "null point"
}
return fmt.Sprintf("%.1f, %.1f", src.X, src.Y)
}
func Example_CustomType() {
conn, err := pgx.Connect(context.Background(), os.Getenv("PGX_TEST_DATABASE"))
if err != nil {
fmt.Printf("Unable to establish connection: %v", err)
return
}
defer conn.Close(context.Background())
if conn.PgConn().ParameterStatus("crdb_version") != "" {
// Skip test / example when running on CockroachDB which doesn't support the point type. Since an example can't be
// skipped fake success instead.
fmt.Println("null point")
fmt.Println("1.5, 2.5")
return
}
// Override registered handler for point
conn.ConnInfo().RegisterDataType(pgtype.DataType{
Value: &Point{},
Name: "point",
OID: 600,
})
p := &Point{}
err = conn.QueryRow(context.Background(), "select null::point").Scan(p)
if err != nil {
fmt.Println(err)
return
}
fmt.Println(p)
err = conn.QueryRow(context.Background(), "select point(1.5,2.5)").Scan(p)
if err != nil {
fmt.Println(err)
return
}
fmt.Println(p)
// Output:
// null point
// 1.5, 2.5
}
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