model: Add strict Ingredient.Validate()

2 files changed, 54 insertions, 1 deletions

diff --git a/model/ingredient.go b/model/ingredient.go
index 85a4729..9922060 100644
--- a/model/ingredient.go
+++ b/model/ingredient.go
@@ -15,11 +15,46 @@ type Ingredient struct {
 	Step   string `json:"step"`
 }
 
+func (i *Ingredient) Validate() error {
+	var err error
+
+	if i.Id != "" {
+		err = isPositiveOrZeroInt(i.Id)
+		if err != nil {
+			return fmt.Errorf("Invalid ingredient ID: %w", err)
+		}
+	}
+
+	err = isPositiveOrZeroInt(i.Index)
+	if err != nil {
+		return fmt.Errorf("Invalid ingredient index: %w", err)
+	}
+
+	if i.Amount != "" {
+		err = isPositiveOrZeroFloat(i.Amount)
+		if err != nil {
+			return fmt.Errorf("Invalid ingredient amount: %w", err)
+		}
+	}
+
+	err = isPositiveOrZeroInt(i.Step)
+	if err != nil {
+		return fmt.Errorf("Ingredient does not reference a valid step ID: %w", err)
+	}
+
+	return nil
+}
+
 func (i *Ingredient) Create(tx *sql.Tx) error {
 	if i.Id != "" {
 		return fmt.Errorf("Cannot create ingredient if ID is given")
 	}
 
+	err := i.Validate()
+	if err != nil {
+		return err
+	}
+
 	cmd := `
 INSERT INTO ingredients
     ('index', amount, unit, 'type', step)
@@ -67,10 +102,15 @@ WHERE
 		return err
 	}
 
-	return nil
+	return i.Validate()
 }
 
 func (i *Ingredient) Update(tx *sql.Tx) error {
+	err := i.Validate()
+	if err != nil {
+		return err
+	}
+
 	cmd := `
 UPDATE
     ingredients
diff --git a/model/validation.go b/model/validation.go
index d49141d..ac38777 100644
--- a/model/validation.go
+++ b/model/validation.go
@@ -26,3 +26,16 @@ func isPositiveOrZeroInt(s string) error {
 
 	return nil
 }
+
+func isPositiveOrZeroFloat(s string) error {
+	f, err := strconv.ParseFloat(s, 32)
+	if err != nil {
+		return fmt.Errorf("'%s' cannot be casted to floating point number", s)
+	}
+
+	if f < 0 {
+		return fmt.Errorf("'%s' is negative", s)
+	}
+
+	return nil
+}