model: Always pass *sql.Tx to CRUD methods

When nesting objects like steps into other objects like recipes it is
required to pass a *sql.Tx value to the CRUD methods of the inner
object to be able to roll back the whole transaction.

The top level object used to be responsible for the creation of this
*sql.Tx inside its CRUD methods.

This is now moved to the caller of the CRUD methods (here the HTTP
handler function). The advantage is that all CRUD methods now accept a
*sql.Tx as only argument which makes those methods more consistent.

1 files changed, 10 insertions, 44 deletions

diff --git a/model/recipe.go b/model/recipe.go
index 6750426..b1ad781 100644
--- a/model/recipe.go
+++ b/model/recipe.go
@@ -23,12 +23,7 @@ func (r Recipe) String() string {
 	return string(b)
 }
 
-func (r *Recipe) Create() error {
-	tx, err := db.Begin()
-	if err != nil {
-		return err
-	}
-
+func (r *Recipe) Create(tx *sql.Tx) error {
 	cmd := `
 INSERT INTO recipes
     (title, portions, url, notes, created, last_changed)
@@ -39,13 +34,11 @@ VALUES
 	result, err := tx.Exec(cmd, r.Title, r.Portions, r.Url, r.Notes, r.Created,
 		r.LastChanged)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
 	id, err := result.LastInsertId()
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
@@ -53,19 +46,13 @@ VALUES
 
 	err = r.CreateSteps(tx)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
-	return tx.Commit()
+	return nil
 }
 
-func (r *Recipe) Read() error {
-	tx, err := db.Begin()
-	if err != nil {
-		return err
-	}
-
+func (r *Recipe) Read(tx *sql.Tx) error {
 	cmd := `
 SELECT id, title, portions, url, notes, created, last_changed
 FROM recipes
@@ -74,13 +61,11 @@ WHERE id = ?
 
 	rows, err := tx.Query(cmd, r.Id)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 	defer rows.Close()
 
 	if !rows.Next() {
-		rollback(tx)
 		return sql.ErrNoRows
 	}
 
@@ -94,31 +79,23 @@ WHERE id = ?
 		&r.LastChanged,
 	)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
 	err = r.ReadSteps(tx)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
-	return tx.Commit()
+	return nil
 }
 
-func (r *Recipe) Update() error {
-	tx, err := db.Begin()
+func (r *Recipe) Update(tx *sql.Tx) error {
+	err := r.UpdateSteps(tx)
 	if err != nil {
 		return err
 	}
 
-	err = r.UpdateSteps(tx)
-	if err != nil {
-		rollback(tx)
-		return err
-	}
-
 	query := `UPDATE
     recipes
 SET
@@ -133,32 +110,23 @@ WHERE
 	res, err := tx.Exec(query, r.Title, r.Portions, r.Url, r.Notes,
 		r.LastChanged, r.Id)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
 	affected, err := res.RowsAffected()
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 	if affected != 1 {
-		rollback(tx)
 		return fmt.Errorf("Recipe update affected %d rows instead of 1", affected)
 	}
 
-	return tx.Commit()
+	return nil
 }
 
-func (r *Recipe) Delete() error {
-	tx, err := db.Begin()
-	if err != nil {
-		return err
-	}
-
-	err = r.DeleteSteps(tx)
+func (r *Recipe) Delete(tx *sql.Tx) error {
+	err := r.DeleteSteps(tx)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
@@ -171,17 +139,15 @@ WHERE
 
 	result, err := tx.Exec(query, r.Id)
 	if err != nil {
-		rollback(tx)
 		return err
 	}
 
 	rows, err := result.RowsAffected()
 	if rows != 1 {
-		rollback(tx)
 		return errors.New("Recipe deletion did not affect exactly one row")
 	}
 
-	return tx.Commit()
+	return nil
 }
 
 func RecipeTestData() []Recipe {