1 files changed, 40 insertions, 1 deletions

diff --git a/model/step.go b/model/step.go
index e3fa24b..89a9efd 100644
--- a/model/step.go
+++ b/model/step.go
@@ -20,11 +20,45 @@ func (s Step) String() string {
 	return string(b)
 }
 
+func (s *Step) Validate() error {
+	var err error
+
+	if s.Id != "" {
+		err = isPositiveOrZeroInt(s.Id)
+		if err != nil {
+			return fmt.Errorf("Invalid step ID: %w", err)
+		}
+	}
+
+	if s.Index != "" {
+		err = isPositiveOrZeroInt(s.Index)
+		if err != nil {
+			return fmt.Errorf("Invalid step index: %w", err)
+		}
+	}
+
+	if s.Text == "" {
+		return fmt.Errorf("Step text must not be empty")
+	}
+
+	err = isPositiveOrZeroInt(s.Recipe)
+	if err != nil {
+		return fmt.Errorf("Step does not reference a valid recipe ID: %w", err)
+	}
+
+	return nil
+}
+
 func (s *Step) Create(tx *sql.Tx) error {
 	if s.Id != "" {
 		return fmt.Errorf("Cannot create step if ID is given")
 	}
 
+	err := s.Validate()
+	if err != nil {
+		return err
+	}
+
 	cmd := `
 INSERT INTO steps
     ('index', text, recipe)
@@ -127,10 +161,15 @@ WHERE
 		}
 	}
 
-	return nil
+	return s.Validate()
 }
 
 func (s *Step) Update(tx *sql.Tx) error {
+	err := s.Validate()
+	if err != nil {
+		return err
+	}
+
 	oldIngredients, err := s.getIngredientIds(tx)
 	if err != nil {
 		return err