model: Add helper function for safe CRUD

This removes the redundant setup of a database/sql.Tx in each HTTP
handler.

3 files changed, 23 insertions, 56 deletions

diff --git a/controller/recipe.go b/controller/recipe.go
index da58d35..9427b0d 100644
--- a/controller/recipe.go
+++ b/controller/recipe.go
@@ -18,20 +18,8 @@ func RecipeCreate(w http.ResponseWriter, r *http.Request) {
 	recipe.LastChanged = fmt.Sprint(time.Now().Unix())
 	recipe.Created = recipe.LastChanged
 
-	tx, err := model.NewTx()
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = recipe.Create(tx)
-	if err != nil {
-		model.Rollback(tx)
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = tx.Commit()
+	var obj model.Object = &recipe
+	err := model.SafeCrud(obj.Create)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -61,20 +49,8 @@ func RecipeUpdate(w http.ResponseWriter, r *http.Request) {
 
 	recipe.LastChanged = fmt.Sprint(time.Now().Unix())
 
-	tx, err := model.NewTx()
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = recipe.Update(tx)
-	if err != nil {
-		model.Rollback(tx)
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = tx.Commit()
+	var obj model.Object = &recipe
+	err = model.SafeCrud(obj.Update)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -87,20 +63,8 @@ func RecipeDelete(w http.ResponseWriter, r *http.Request) {
 	recipe := model.Recipe{}
 	recipe.Id = mux.Vars(r)[`id`]
 
-	tx, err := model.NewTx()
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = recipe.Delete(tx)
-	if err != nil {
-		model.Rollback(tx)
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = tx.Commit()
+	var obj model.Object = &recipe
+	err := model.SafeCrud(obj.Delete)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
diff --git a/model/object.go b/model/object.go
index 63ef419..bcbba3e 100644
--- a/model/object.go
+++ b/model/object.go
@@ -10,3 +10,18 @@ type Object interface {
 	Update(tx *sql.Tx) error
 	Delete(tx *sql.Tx) error
 }
+
+func SafeCrud(crud func(tx *sql.Tx) error) error {
+	tx, err := NewTx()
+	if err != nil {
+		return err
+	}
+
+	err = crud(tx)
+	if err != nil {
+		Rollback(tx)
+		return err
+	}
+
+	return tx.Commit()
+}
diff --git a/view/recipe.go b/view/recipe.go
index 52b7a7e..ba670a2 100644
--- a/view/recipe.go
+++ b/view/recipe.go
@@ -12,20 +12,8 @@ func RecipeRead(w http.ResponseWriter, r *http.Request) {
 	recipe := model.Recipe{}
 	recipe.Id = mux.Vars(r)[`id`]
 
-	tx, err := model.NewTx()
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = recipe.Read(tx)
-	if err != nil {
-		model.Rollback(tx)
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	err = tx.Commit()
+	var obj model.Object = &recipe
+	err := model.SafeCrud(obj.Read)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return