model: CRUD methods only for targeted objects

A create, read, update or delete (CRUD) method should only care about
the object which provides the receiver and the relations to its child
objects.

For example the method

	func (r *Recipe) Create(tx *sql.Tx) error {}

should only create the relational data inside the database for the
recipe, not for the steps nested into this Recipe struct. This should be
covered by the

	func (s *Step) Create(tx *sql.Tx) error {}

method which is then called by `func (r *Recipe) Create()`.

This has the advantage that every CRUD method has a constraint scope and
is more unified since the Step CRUD methods now have a Step struct as
receiver instead of a Recipe receiver.

1 files changed, 90 insertions, 16 deletions

diff --git a/model/recipe.go b/model/recipe.go
index b1ad781..c4f0d47 100644
--- a/model/recipe.go
+++ b/model/recipe.go
@@ -24,6 +24,10 @@ func (r Recipe) String() string {
 }
 
 func (r *Recipe) Create(tx *sql.Tx) error {
+	if r.Id != "" {
+		return fmt.Errorf("Cannot create recipe if ID is given")
+	}
+
 	cmd := `
 INSERT INTO recipes
     (title, portions, url, notes, created, last_changed)
@@ -44,19 +48,60 @@ VALUES
 
 	r.Id = fmt.Sprint(id)
 
-	err = r.CreateSteps(tx)
-	if err != nil {
-		return err
+	for i := range r.Steps {
+		r.Steps[i].Recipe = r.Id
+		r.Steps[i].Index = fmt.Sprint(i)
+		err = r.Steps[i].Create(tx)
+		if err != nil {
+			return err
+		}
 	}
 
 	return nil
 }
 
+func (r *Recipe) getStepIds(tx *sql.Tx) ([]Step, error) {
+	retval := make([]Step, 0)
+
+	cmd := `
+SELECT
+    id
+FROM
+    steps
+WHERE
+    recipe = ?
+ORDER BY
+    'index' ASC
+`
+
+	rows, err := tx.Query(cmd, r.Id)
+	if err != nil {
+		return retval, err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		s := Step{}
+
+		err = rows.Scan(&s.Id)
+		if err != nil {
+			return retval, err
+		}
+
+		retval = append(retval, s)
+	}
+
+	return retval, nil
+}
+
 func (r *Recipe) Read(tx *sql.Tx) error {
 	cmd := `
-SELECT id, title, portions, url, notes, created, last_changed
-FROM recipes
-WHERE id = ?
+SELECT
+    title, portions, url, notes, created, last_changed
+FROM
+    recipes
+WHERE
+    id = ?
 `
 
 	rows, err := tx.Query(cmd, r.Id)
@@ -70,7 +115,6 @@ WHERE id = ?
 	}
 
 	err = rows.Scan(
-		&r.Id,
 		&r.Title,
 		&r.Portions,
 		&r.Url,
@@ -82,32 +126,57 @@ WHERE id = ?
 		return err
 	}
 
-	err = r.ReadSteps(tx)
+	r.Steps, err = r.getStepIds(tx)
 	if err != nil {
 		return err
 	}
 
+	for i := range r.Steps {
+		err = r.Steps[i].Read(tx)
+		if err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
 
 func (r *Recipe) Update(tx *sql.Tx) error {
-	err := r.UpdateSteps(tx)
+	oldSteps, err := r.getStepIds(tx)
 	if err != nil {
 		return err
 	}
 
-	query := `UPDATE
+	for i := range oldSteps {
+		err = oldSteps[i].Delete(tx)
+		if err != nil {
+			return err
+		}
+	}
+
+	for i := range r.Steps {
+		r.Steps[i].Index = fmt.Sprint(i)
+		r.Steps[i].Recipe = r.Id
+		r.Steps[i].Create(tx)
+		if err != nil {
+			return err
+		}
+	}
+
+	cmd := `
+UPDATE
     recipes
 SET
     title = ?,
 	portions = ?,
 	url = ?,
 	notes = ?,
+	created = ?,
 	last_changed = ?
 WHERE
     id = ?`
 
-	res, err := tx.Exec(query, r.Title, r.Portions, r.Url, r.Notes,
+	res, err := tx.Exec(cmd, r.Title, r.Portions, r.Url, r.Notes, r.Created,
 		r.LastChanged, r.Id)
 	if err != nil {
 		return err
@@ -125,19 +194,26 @@ WHERE
 }
 
 func (r *Recipe) Delete(tx *sql.Tx) error {
-	err := r.DeleteSteps(tx)
+	oldSteps, err := r.getStepIds(tx)
 	if err != nil {
 		return err
 	}
 
-	query := `
+	for i := range oldSteps {
+		err = oldSteps[i].Delete(tx)
+		if err != nil {
+			return err
+		}
+	}
+
+	cmd := `
 DELETE FROM
     recipes
 WHERE
     id = ?
 `
 
-	result, err := tx.Exec(query, r.Id)
+	result, err := tx.Exec(cmd, r.Id)
 	if err != nil {
 		return err
 	}
@@ -153,7 +229,6 @@ WHERE
 func RecipeTestData() []Recipe {
 	return []Recipe{
 		{
-			Id:          "1",
 			Title:       "Pancakes",
 			Portions:    "4",
 			Url:         "https://example.org",
@@ -167,7 +242,6 @@ func RecipeTestData() []Recipe {
 			},
 		},
 		{
-			Id:          "2",
 			Title:       "Burger",
 			Portions:    "2",
 			Url:         "https://xengineering.eu/git/ceres",