more refactors

internal/db/getbyfield.go

@@ -0,0 +1,83 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/pkg/errors"
+	"github.com/uptrace/bun"
+)
+
+type ListFilter struct {
+	filters []Filter
+}
+
+func NewListFilter() *ListFilter {
+	return &ListFilter{[]Filter{}}
+}
+
+func (f *ListFilter) Add(field string, value any) {
+	f.filters = append(f.filters, Filter{field, value})
+}
+
+type fieldgetter[T any] struct {
+	q     *bun.SelectQuery
+	field string
+	value any
+}
+
+func (g *fieldgetter[T]) get(ctx context.Context) (*T, error) {
+	if g.field == "id" && (g.value).(int) < 1 {
+		return nil, errors.New("invalid id")
+	}
+	model := new(T)
+	err := g.q.
+		Where("? = ?", bun.Ident(g.field), g.value).
+		Scan(ctx, model)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return nil, nil
+		}
+		return nil, errors.Wrap(err, "bun.SelectQuery.Scan")
+	}
+	return model, nil
+}
+
+func (g *fieldgetter[T]) GetFirst(ctx context.Context) (*T, error) {
+	g.q = g.q.Limit(1)
+	return g.get(ctx)
+}
+
+func (g *fieldgetter[T]) GetAll(ctx context.Context) (*T, error) {
+	return g.get(ctx)
+}
+
+func (g *fieldgetter[T]) Relation(name string, apply ...func(*bun.SelectQuery) *bun.SelectQuery) *fieldgetter[T] {
+	g.q = g.q.Relation(name, apply...)
+	return g
+}
+
+func (g *fieldgetter[T]) Join(join string, args ...any) *fieldgetter[T] {
+	g.q = g.q.Join(join, args...)
+	return g
+}
+
+// GetByField retrieves a single record by field name
+func GetByField[T any](
+	tx bun.Tx,
+	field string,
+	value any,
+) *fieldgetter[T] {
+	return &fieldgetter[T]{
+		tx.NewSelect().Model((*T)(nil)),
+		field,
+		value,
+	}
+}
+
+func GetByID[T any](
+	tx bun.Tx,
+	id int,
+) *fieldgetter[T] {
+	return GetByField[T](tx, "id", id)
+}