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// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
// SPDX-License-Identifier: Apache-2.0
package oblast
import (
"context"
"database/sql"
"fmt"
"go.xyrillian.de/oblast/handle"
)
// Handle contains behavior that database handles must offer to Oblast.
// The standard-library types [*sql.DB] and [*sql.Tx] can satisfy this interface through the [Wrap] function.
// Custom implementations of this interface can be used to connect non-std database drivers to Oblast.
type Handle = handle.Handle
// SqlHandle wraps types like [*sql.DB] or [*sql.Tx] into a [Handle] that can be used with Oblast.
// TODO: separate types for wrapped *sql.DB and wrapped *sql.Tx, so we can have those types as embedded fields and forward method implementations
type SqlHandle[T SqlExecutor] struct {
// The original database or transaction handle.
// It is safe to read this field to execute operations that Oblast does not handle (e.g. transactions, savepoints or OLAP queries).
Base T
// If this is not true, then any methods on this type will panic.
// This is just to enforce that the handle is constructed with Wrap(), thus guaranteeing future compatibility if actual important private struct fields are added later.
ok bool
}
// Wrap converts an [*sql.DB] or [*sql.Tx] into a [Handle] that can be used with Oblast functions.
func Wrap[T SqlExecutor](dbOrTx T) SqlHandle[T] {
return SqlHandle[T]{Base: dbOrTx, ok: true}
}
// SqlExecutor is an interface covered by both [*sql.DB] and [*sql.Tx].
// It appears in the signature of function [Wrap].
type SqlExecutor interface {
ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
PrepareContext(ctx context.Context, query string) (*sql.Stmt, error)
QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error)
QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row
}
// static assertion that the respective types implement the interface
var (
_ SqlExecutor = &sql.DB{}
_ SqlExecutor = &sql.Tx{}
)
// OblastPrepare implements the [Handle] interface.
func (h SqlHandle[T]) OblastPrepare(ctx context.Context, query string, repeated bool) (handle.Statement, error) {
if !h.ok {
panic("SqlHandle was not constructed through oblast.Wrap()!")
}
if !repeated {
return wrappedStatement{h.Base, query, nil}, nil
}
stmt, err := h.Base.PrepareContext(ctx, query)
if err != nil {
return nil, fmt.Errorf("during Prepare(): %w", err)
}
return wrappedStatement{h.Base, query, stmt}, nil
}
// OblastQuery implements the [Handle] interface.
func (h SqlHandle[T]) OblastQuery(ctx context.Context, query string, args []any) (handle.Rows, error) {
if !h.ok {
panic("SqlHandle was not constructed through oblast.Wrap()!")
}
return h.Base.QueryContext(ctx, query, args...) //nolint:rowserrcheck // the caller does the check
}
type wrappedStatement struct {
db SqlExecutor
query string
stmt *sql.Stmt // nil if repeated = false
}
// Close implements the [Statement] interface.
func (s wrappedStatement) Close() error {
if s.stmt == nil {
return nil
}
return s.stmt.Close()
}
// Exec implements the [Statement] interface.
func (s wrappedStatement) Exec(ctx context.Context, args []any) (sql.Result, error) {
if s.stmt == nil {
return s.db.ExecContext(ctx, s.query, args...)
} else {
return s.stmt.ExecContext(ctx, args...)
}
}
// QueryRow implements the [Statement] interface.
func (s wrappedStatement) QueryRow(ctx context.Context, args, slots []any) error {
if s.stmt == nil {
return s.db.QueryRowContext(ctx, s.query, args...).Scan(slots...)
} else {
return s.stmt.QueryRowContext(ctx, args...).Scan(slots...)
}
}
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