Merge pull request #14 from faide/master

Added support for Numeric type in db storage

decimal.go

@@ -469,14 +469,30 @@ func (d Decimal) MarshalJSON() ([]byte, error) {
 
 // Scan implements the sql.Scanner interface for database deserialization.
 func (d *Decimal) Scan(value interface{}) error {
-	str, err := unquoteIfQuoted(value)
+	// first try to see if the data is stored in database as a Numeric datatype
+	switch v := value.(type) {
+
+	case float64:
+		// numeric in sqlite3 sends us float64
+		*d = NewFromFloat(v)
+		return nil
+
+	case int64:
+		// at least in sqlite3 when the value is 0 in db, the data is sent
+		// to us as an int64 instead of a float64 ...
+		*d = New(v, 0)
+		return nil
+
+	default:
+		// default is trying to interpret value stored as string
+		str, err := unquoteIfQuoted(v)
 		if err != nil {
 			return err
 		}
 		*d, err = NewFromString(str)
-
 		return err
 	}
+}
 
 // Value implements the driver.Valuer interface for database serialization.
 func (d Decimal) Value() (driver.Value, error) {

decimal_test.go

@@ -813,6 +813,67 @@ func TestDecimal_Max(t *testing.T) {
 	}
 }
 
+func TestDecimal_Scan(t *testing.T) {
+	// test the Scan method the implements the
+	// sql.Scanner interface
+	// check for the for different type of values
+	// that are possible to be received from the database
+	// drivers
+
+	// in normal operations the db driver (sqlite at least)
+	// will return an int64 if you specified a numeric format
+	a := Decimal{}
+	dbvalue := float64(54.33)
+	expected := NewFromFloat(dbvalue)
+
+	err := a.Scan(dbvalue)
+	if err != nil {
+		// Scan failed... no need to test result value
+		t.Errorf("a.Scan(54.33) failed with message: %s", err)
+
+	} else {
+		// Scan suceeded... test resulting values
+		if !a.Equals(expected) {
+			t.Errorf("%s does not equal to %s", a, expected)
+		}
+	}
+
+	// at least SQLite returns an int64 when 0 is stored in the db
+	// and you specified a numeric format on the schema
+	dbvalue_int := int64(0)
+	expected = New(dbvalue_int, 0)
+
+	err = a.Scan(dbvalue_int)
+	if err != nil {
+		// Scan failed... no need to test result value
+		t.Errorf("a.Scan(0) failed with message: %s", err)
+
+	} else {
+		// Scan suceeded... test resulting values
+		if !a.Equals(expected) {
+			t.Errorf("%s does not equal to %s", a, expected)
+		}
+	}
+
+	// in case you specified a varchar in your SQL schema,
+	// the database driver will return byte slice []byte
+	value_str := "535.666"
+	dbvalue_str := []byte(value_str)
+	expected, err = NewFromString(value_str)
+
+	err = a.Scan(dbvalue_str)
+	if err != nil {
+		// Scan failed... no need to test result value
+		t.Errorf("a.Scan('535.666') failed with message: %s", err)
+
+	} else {
+		// Scan suceeded... test resulting values
+		if !a.Equals(expected) {
+			t.Errorf("%s does not equal to %s", a, expected)
+		}
+	}
+}
+
 // old tests after this line
 
 func TestDecimal_Scale(t *testing.T) {