Listing 10.8: Detecting constraint errors

What's changed?

--- a/link/sqlite/sqlite.go
+++ b/link/sqlite/sqlite.go
@@ -3,11 +3,12 @@
 import (
 	"context"
 	"database/sql"
 	_ "embed"
+	"errors"
 	"fmt"
 	"testing"
 
-	_ "modernc.org/sqlite"
+	"modernc.org/sqlite"
 )
 
 //go:embed schema.sql
@@ -50,0 +52,9 @@
+
+func isPrimaryKeyViolation(err error) bool {
+	var serr *sqlite.Error
+	if errors.As(err, &serr) {
+		return serr.Code() == 1555
+		// See: sqlite.org/rescode.html#constraint_primarykey
+	}
+	return false
+}

Code in the file

link / sqlite / sqlite.go

package sqlite

import (
	"context"
	"database/sql"
	_ "embed"
	"errors"
	"fmt"
	"testing"

	"modernc.org/sqlite"
)

//go:embed schema.sql
var schema string

// Dial connects to SQLite and applies the schema for convenience.
func Dial(ctx context.Context, dsn string) (*sql.DB, error) {
	db, err := sql.Open("sqlite", dsn)
	if err != nil {
		return nil, fmt.Errorf("opening: %w", err)
	}
	if err := db.PingContext(ctx); err != nil {
		return nil, fmt.Errorf("pinging: %w", err)
	}
	if _, err := db.ExecContext(ctx, schema); err != nil {
		return nil, fmt.Errorf("applying schema: %w", err)
	}
	return db, nil
}

// DialTestDB connects to a unique in-memory SQLite database.
func DialTestDB(tb testing.TB) *sql.DB {
	tb.Helper()

	dsn := fmt.Sprintf(
		"file:%s?mode=memory&cache=shared",
		tb.Name(),
	)
	db, err := Dial(tb.Context(), dsn)
	if err != nil {
		tb.Fatalf("DialTestDB: %v", err)
	}
	tb.Cleanup(func() {
		if err := db.Close(); err != nil {
			tb.Logf("DialTestDB: closing: %v", err)
		}
	})

	return db
}

func isPrimaryKeyViolation(err error) bool {
	var serr *sqlite.Error
	if errors.As(err, &serr) {
		return serr.Code() == 1555
		// See: sqlite.org/rescode.html#constraint_primarykey
	}
	return false
}