[MM-55096] Introduce generic StoreResult (#25086)

server/channels/app/channel.go

@@ -1401,18 +1401,18 @@ func (a *App) updateChannelMember(c request.CTX, member *model.ChannelMember) (*
 }
 
 func (a *App) DeleteChannel(c request.CTX, channel *model.Channel, userID string) *model.AppError {
-	ihc := make(chan store.StoreResult, 1)
+	ihc := make(chan store.GenericStoreResult[[]*model.IncomingWebhook], 1)
-	ohc := make(chan store.StoreResult, 1)
+	ohc := make(chan store.GenericStoreResult[[]*model.OutgoingWebhook], 1)
 
 	go func() {
 		webhooks, err := a.Srv().Store().Webhook().GetIncomingByChannel(channel.Id)
-		ihc <- store.StoreResult{Data: webhooks, NErr: err}
+		ihc <- store.GenericStoreResult[[]*model.IncomingWebhook]{Data: webhooks, NErr: err}
 		close(ihc)
 	}()
 
 	go func() {
 		outgoingHooks, err := a.Srv().Store().Webhook().GetOutgoingByChannel(channel.Id, -1, -1)
-		ohc <- store.StoreResult{Data: outgoingHooks, NErr: err}
+		ohc <- store.GenericStoreResult[[]*model.OutgoingWebhook]{Data: outgoingHooks, NErr: err}
 		close(ohc)
 	}()
 
@@ -1441,9 +1441,6 @@ func (a *App) DeleteChannel(c request.CTX, channel *model.Channel, userID string
 		return model.NewAppError("DeleteChannel", "app.webhooks.get_outgoing_by_channel.app_error", nil, "", http.StatusInternalServerError).Wrap(ohcresult.NErr)
 	}
 
-	incomingHooks := ihcresult.Data.([]*model.IncomingWebhook)
-	outgoingHooks := ohcresult.Data.([]*model.OutgoingWebhook)
-
 	if channel.DeleteAt > 0 {
 		err := model.NewAppError("deleteChannel", "api.channel.delete_channel.deleted.app_error", nil, "", http.StatusBadRequest)
 		return err
@@ -1492,14 +1489,14 @@ func (a *App) DeleteChannel(c request.CTX, channel *model.Channel, userID string
 	}
 
 	now := model.GetMillis()
-	for _, hook := range incomingHooks {
+	for _, hook := range ihcresult.Data {
 		if err := a.Srv().Store().Webhook().DeleteIncoming(hook.Id, now); err != nil {
 			c.Logger().Warn("Encountered error deleting incoming webhook", mlog.String("hook_id", hook.Id), mlog.Err(err))
 		}
 		a.Srv().Platform().InvalidateCacheForWebhook(hook.Id)
 	}
 
-	for _, hook := range outgoingHooks {
+	for _, hook := range ohcresult.Data {
 		if err := a.Srv().Store().Webhook().DeleteOutgoing(hook.Id, now); err != nil {
 			c.Logger().Warn("Encountered error deleting outgoing webhook", mlog.String("hook_id", hook.Id), mlog.Err(err))
 		}

server/channels/store/store.go

@@ -15,6 +15,7 @@ import (
 	"github.com/mattermost/mattermost/server/v8/channels/product"
 )
 
+// Deprecated: Use GenericStoreResult instead.
 type StoreResult struct {
 	Data any
 
@@ -22,6 +23,15 @@ type StoreResult struct {
 	NErr error
 }
 
+// GenericStoreResult is a type safe version of StoreResult.
+// Once all the code is migrated to use GenericStoreResult, it should be renamed to StoreResult.
+type GenericStoreResult[T any] struct {
+	Data T
+
+	// NErr a temporary field used by the new code for the AppError migration. This will later become Err when the entire store is migrated.
+	NErr error
+}
+
 type Store interface {
 	Team() TeamStore
 	Channel() ChannelStore