Introduce model.Transaction()

It is a very common pattern that some function needs to access the
database and wants to wrap all the actions into one transaction.

The advantage of a transaction is that it is ACID:

- atomic
- consistent
- isolated
- durable

In Go it is required to request a new transaction, execute functionality
on it and handle rollback or commit of this transaction based on the
success of the operation.

All this and the error handling can be written down in the
model.Transaction() function exactly once. The full signature of it is:

	func Transaction(f func(*sql.Tx) error) error

It requires a function or closure passed as argument which takes the
transaction (*sql.Tx) and returns an error which might be nil.

This is very generic. It is applied to:

- injecting test data
- database migrations
- data read requests
- data write requests

1 files changed, 3 insertions, 3 deletions

diff --git a/controller/recipe.go b/controller/recipe.go
index 9427b0d..9529b2a 100644
--- a/controller/recipe.go
+++ b/controller/recipe.go
@@ -19,7 +19,7 @@ func RecipeCreate(w http.ResponseWriter, r *http.Request) {
 	recipe.Created = recipe.LastChanged
 
 	var obj model.Object = &recipe
-	err := model.SafeCrud(obj.Create)
+	err := model.Transaction(obj.Create)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -50,7 +50,7 @@ func RecipeUpdate(w http.ResponseWriter, r *http.Request) {
 	recipe.LastChanged = fmt.Sprint(time.Now().Unix())
 
 	var obj model.Object = &recipe
-	err = model.SafeCrud(obj.Update)
+	err = model.Transaction(obj.Update)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -64,7 +64,7 @@ func RecipeDelete(w http.ResponseWriter, r *http.Request) {
 	recipe.Id = mux.Vars(r)[`id`]
 
 	var obj model.Object = &recipe
-	err := model.SafeCrud(obj.Delete)
+	err := model.Transaction(obj.Delete)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return