refactor to mautrix 0.17.x; update deps

vendor/go.mau.fi/util/dbutil/queryhelper.go

@@ -0,0 +1,105 @@
+// Copyright (c) 2023 Tulir Asokan
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package dbutil
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+
+	"golang.org/x/exp/constraints"
+)
+
+// DataStruct is an interface for structs that represent a single database row.
+type DataStruct[T any] interface {
+	Scan(row Scannable) (T, error)
+}
+
+// QueryHelper is a generic helper struct for SQL query execution boilerplate.
+//
+// After implementing the Scan and Init methods in a data struct, the query
+// helper allows writing query functions in a single line.
+type QueryHelper[T DataStruct[T]] struct {
+	db      *Database
+	newFunc func(qh *QueryHelper[T]) T
+}
+
+func MakeQueryHelper[T DataStruct[T]](db *Database, new func(qh *QueryHelper[T]) T) *QueryHelper[T] {
+	return &QueryHelper[T]{db: db, newFunc: new}
+}
+
+// ValueOrErr is a helper function that returns the value if err is nil, or
+// returns nil and the error if err is not nil. It can be used to avoid
+// `if err != nil { return nil, err }` boilerplate in certain cases like
+// DataStruct.Scan implementations.
+func ValueOrErr[T any](val *T, err error) (*T, error) {
+	if err != nil {
+		return nil, err
+	}
+	return val, nil
+}
+
+// StrPtr returns a pointer to the given string, or nil if the string is empty.
+func StrPtr[T ~string](val T) *string {
+	if val == "" {
+		return nil
+	}
+	strVal := string(val)
+	return &strVal
+}
+
+// NumPtr returns a pointer to the given number, or nil if the number is zero.
+func NumPtr[T constraints.Integer | constraints.Float](val T) *T {
+	if val == 0 {
+		return nil
+	}
+	return &val
+}
+
+func (qh *QueryHelper[T]) GetDB() *Database {
+	return qh.db
+}
+
+func (qh *QueryHelper[T]) New() T {
+	return qh.newFunc(qh)
+}
+
+// Exec executes a query with ExecContext and returns the error.
+//
+// It omits the sql.Result return value, as it is rarely used. When the result
+// is wanted, use `qh.GetDB().Exec(...)` instead, which is
+// otherwise equivalent.
+func (qh *QueryHelper[T]) Exec(ctx context.Context, query string, args ...any) error {
+	_, err := qh.db.Exec(ctx, query, args...)
+	return err
+}
+
+func (qh *QueryHelper[T]) scanNew(row Scannable) (T, error) {
+	return qh.New().Scan(row)
+}
+
+// QueryOne executes a query with QueryRowContext, uses the associated DataStruct
+// to scan it, and returns the value. If the query returns no rows, it returns nil
+// and no error.
+func (qh *QueryHelper[T]) QueryOne(ctx context.Context, query string, args ...any) (val T, err error) {
+	val, err = qh.scanNew(qh.db.QueryRow(ctx, query, args...))
+	if errors.Is(err, sql.ErrNoRows) {
+		err = nil
+	}
+	return val, err
+}
+
+// QueryMany executes a query with QueryContext, uses the associated DataStruct
+// to scan each row, and returns the values. If the query returns no rows, it
+// returns a non-nil zero-length slice and no error.
+func (qh *QueryHelper[T]) QueryMany(ctx context.Context, query string, args ...any) ([]T, error) {
+	rows, err := qh.db.Query(ctx, query, args...)
+	if err != nil {
+		return nil, err
+	}
+	return NewRowIter(rows, qh.scanNew).AsList()
+}