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pgxscan.go
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pgxscan.go
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package pgxscan
import (
"context"
"database/sql"
"errors"
"fmt"
"github.com/jackc/pgx/v5"
"github.com/jackc/pgx/v5/pgxpool"
"github.com/georgysavva/scany/v2/dbscan"
)
// Querier is something that pgxscan can query and get the pgx.Rows from.
// For example, it can be: *pgxpool.Pool, *pgx.Conn or pgx.Tx.
type Querier interface {
Query(ctx context.Context, query string, args ...interface{}) (pgx.Rows, error)
}
var (
_ Querier = &pgxpool.Pool{}
_ Querier = &pgx.Conn{}
_ Querier = pgx.Tx(nil)
)
// Select is a package-level helper function that uses the DefaultAPI object.
// See API.Select for details.
func Select(ctx context.Context, db Querier, dst interface{}, query string, args ...interface{}) error {
return DefaultAPI.Select(ctx, db, dst, query, args...)
}
// Get is a package-level helper function that uses the DefaultAPI object.
// See API.Get for details.
func Get(ctx context.Context, db Querier, dst interface{}, query string, args ...interface{}) error {
return DefaultAPI.Get(ctx, db, dst, query, args...)
}
// ScanAll is a package-level helper function that uses the DefaultAPI object.
// See API.ScanAll for details.
func ScanAll(dst interface{}, rows pgx.Rows) error {
return DefaultAPI.ScanAll(dst, rows)
}
// ScanOne is a package-level helper function that uses the DefaultAPI object.
// See API.ScanOne for details.
func ScanOne(dst interface{}, rows pgx.Rows) error {
return DefaultAPI.ScanOne(dst, rows)
}
// RowScanner is a wrapper around the dbscan.RowScanner type.
// See dbscan.RowScanner for details.
type RowScanner struct {
*dbscan.RowScanner
}
// NewRowScanner is a package-level helper function that uses the DefaultAPI object.
// See API.NewRowScanner for details.
func NewRowScanner(rows pgx.Rows) *RowScanner {
return DefaultAPI.NewRowScanner(rows)
}
// ScanRow is a package-level helper function that uses the DefaultAPI object.
// See API.ScanRow for details.
func ScanRow(dst interface{}, rows pgx.Rows) error {
return DefaultAPI.ScanRow(dst, rows)
}
// NewDBScanAPI creates a new dbscan API object with default configuration settings for pgxscan.
func NewDBScanAPI(opts ...dbscan.APIOption) (*dbscan.API, error) {
defaultOpts := []dbscan.APIOption{
dbscan.WithScannableTypes(
(*sql.Scanner)(nil),
),
}
opts = append(defaultOpts, opts...)
api, err := dbscan.NewAPI(opts...)
return api, err
}
// API is a wrapper around the dbscan.API type.
// See dbscan.API for details.
type API struct {
dbscanAPI *dbscan.API
}
// NewAPI creates new API instance from dbscan.API instance.
func NewAPI(dbscanAPI *dbscan.API) (*API, error) {
api := &API{dbscanAPI: dbscanAPI}
return api, nil
}
// Select is a high-level function that queries rows from Querier and calls the ScanAll function.
// See ScanAll for details.
func (api *API) Select(ctx context.Context, db Querier, dst interface{}, query string, args ...interface{}) error {
rows, err := db.Query(ctx, query, args...)
if err != nil {
return fmt.Errorf("scany: query multiple result rows: %w", err)
}
if err := api.ScanAll(dst, rows); err != nil {
return fmt.Errorf("scanning all: %w", err)
}
return nil
}
// Get is a high-level function that queries rows from Querier and calls the ScanOne function.
// See ScanOne for details.
func (api *API) Get(ctx context.Context, db Querier, dst interface{}, query string, args ...interface{}) error {
rows, err := db.Query(ctx, query, args...)
if err != nil {
return fmt.Errorf("scany: query one result row: %w", err)
}
if err := api.ScanOne(dst, rows); err != nil {
return fmt.Errorf("scanning one: %w", err)
}
return nil
}
// ScanAll is a wrapper around the dbscan.ScanAll function.
// See dbscan.ScanAll for details.
func (api *API) ScanAll(dst interface{}, rows pgx.Rows) error {
return api.dbscanAPI.ScanAll(dst, NewRowsAdapter(rows))
}
// ScanOne is a wrapper around the dbscan.ScanOne function.
// See dbscan.ScanOne for details. If no rows are found it
// returns a pgx.ErrNoRows error.
func (api *API) ScanOne(dst interface{}, rows pgx.Rows) error {
switch err := api.dbscanAPI.ScanOne(dst, NewRowsAdapter(rows)); {
case dbscan.NotFound(err):
return fmt.Errorf("%w", pgx.ErrNoRows)
case err != nil:
return fmt.Errorf("%w", err)
default:
return nil
}
}
// NotFound is a helper function to check if an error
// is `pgx.ErrNoRows`.
func NotFound(err error) bool {
return errors.Is(err, pgx.ErrNoRows)
}
// NewRowScanner returns a new RowScanner instance.
func (api *API) NewRowScanner(rows pgx.Rows) *RowScanner {
ra := NewRowsAdapter(rows)
return &RowScanner{RowScanner: api.dbscanAPI.NewRowScanner(ra)}
}
// ScanRow is a wrapper around the dbscan.ScanRow function.
// See dbscan.ScanRow for details.
func (api *API) ScanRow(dst interface{}, rows pgx.Rows) error {
return api.dbscanAPI.ScanRow(dst, NewRowsAdapter(rows))
}
// RowsAdapter makes pgx.Rows compliant with the dbscan.Rows interface.
// See dbscan.Rows for details.
type RowsAdapter struct {
pgx.Rows
}
// NewRowsAdapter returns a new RowsAdapter instance.
func NewRowsAdapter(rows pgx.Rows) *RowsAdapter {
return &RowsAdapter{Rows: rows}
}
// Columns implements the dbscan.Rows.Columns method.
func (ra RowsAdapter) Columns() ([]string, error) {
columns := make([]string, len(ra.Rows.FieldDescriptions()))
for i, fd := range ra.Rows.FieldDescriptions() {
columns[i] = fd.Name
}
return columns, nil
}
// Close implements the dbscan.Rows.Close method.
func (ra RowsAdapter) Close() error {
ra.Rows.Close()
return nil
}
// NextResultSet is currently always returning false.
func (ra RowsAdapter) NextResultSet() bool {
// TODO: when pgx issue #308 and #1512 and is fixed mabye we can do something here.
return false
}
func mustNewDBScanAPI(opts ...dbscan.APIOption) *dbscan.API {
api, err := NewDBScanAPI(opts...)
if err != nil {
panic(err)
}
return api
}
func mustNewAPI(dbscanAPI *dbscan.API) *API {
api, err := NewAPI(dbscanAPI)
if err != nil {
panic(err)
}
return api
}
// DefaultAPI is the default instance of API with all configuration settings set to default.
var DefaultAPI = mustNewAPI(mustNewDBScanAPI())