From 3c9e5505ab49ba8cd025c00a6da90ad672443313 Mon Sep 17 00:00:00 2001
From: jdl <jdl@desktop>
Date: Mon, 20 Nov 2023 20:23:44 +0100
Subject: [PATCH] Added some convenience functions.

---
 mdb/collection.go | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/mdb/collection.go b/mdb/collection.go
index 73b035d..a443563 100644
--- a/mdb/collection.go
+++ b/mdb/collection.go
@@ -108,13 +108,14 @@ type indexConfig[T any] struct {
 	Include func(item *T) bool
 }
 
+// A shortcut for c.ByID.Get(tx, &Item{ID:id}).
 func (c *Collection[T]) Get(tx *Snapshot, id uint64) (*T, bool) {
 	x := new(T)
 	c.setID(x, id)
 	return c.ByID.Get(tx, x)
 }
 
-func (c *Collection[T]) List(tx *Snapshot, ids []uint64, out []*T) []*T {
+func (c *Collection[T]) GetList(tx *Snapshot, ids []uint64, out []*T) []*T {
 	if len(ids) == 0 {
 		return out[:0]
 	}
@@ -234,6 +235,18 @@ func (c *Collection[T]) Update(tx *Snapshot, userItem *T) error {
 	return nil
 }
 
+func (c *Collection[T]) UpdateFunc(tx *Snapshot, id uint64, update func(item *T) error) error {
+	item, ok := c.getByID(tx, id)
+	if !ok {
+		return errs.NotFound
+	}
+	itemCopy := c.copy(item)
+	if err := update(itemCopy); err != nil {
+		return err
+	}
+	return c.Update(tx, itemCopy)
+}
+
 func (c *Collection[T]) Upsert(tx *Snapshot, item *T) error {
 	err := c.Insert(tx, item)
 	if err == nil {
@@ -245,6 +258,20 @@ func (c *Collection[T]) Upsert(tx *Snapshot, item *T) error {
 	return err
 }
 
+func (c *Collection[T]) UpsertFunc(tx *Snapshot, id uint64, update func(item *T) error) error {
+	item, ok := c.getByID(tx, id)
+	if !ok {
+		item = new(T)
+		c.setID(item, id)
+	}
+
+	itemCopy := c.copy(item)
+	if err := update(itemCopy); err != nil {
+		return err
+	}
+	return c.Upsert(tx, itemCopy)
+}
+
 func (c *Collection[T]) Delete(tx *Snapshot, itemID uint64) error {
 	if err := c.ensureMutable(tx); err != nil {
 		return err