Support optional boolean query parameters (i.e. pointers)

This commit adds support for boolean query parameters that are optional,
meaning their type is `*bool` rather than `bool`. This is useful in
cases where an API must know whether the parameter was actually
provided, even if it was false, and not just received a zero value.

decoder.go

@@ -174,6 +174,13 @@ func unmarshalField(
 		valueField.SetFloat(value)
 	case reflect.Bool:
 		valueField.SetBool(boolRegex.MatchString(strings.ToLower(params[param])))
+	case reflect.Ptr:
+		if typeField.Elem().Kind() == reflect.Bool {
+			if val, ok := params[param]; ok {
+				b := boolRegex.MatchString(strings.ToLower(val))
+				valueField.Set(reflect.ValueOf(&b))
+			}
+		}
 	case reflect.Slice:
 		// we'll be extracting values from multiParam, generating a slice and
 		// putting it in valueField

decoder_test.go

@@ -22,6 +22,8 @@ func Test_UnmarshalRequest(t *testing.T) {
 					"page":      "2",
 					"page_size": "30",
 					"const":     "two",
+					"bool":      "true",
+					"pbool1":    "0",
 				},
 				MultiValueQueryStringParameters: map[string][]string{
 					"terms":   []string{"one", "two"},
@@ -43,6 +45,10 @@ func Test_UnmarshalRequest(t *testing.T) {
 		assert.Equal(t, int64(30), input.PageSize, "PageSize must be parsed from query")
 		assert.Equal(t, "en-us", input.Language, "Language must be parsed from headers")
 		assert.Equal(t, mockConstTwo, input.Const, "Const must be parsed from query")
+		assert.True(t, input.Bool, "Bool must be true")
+		assert.NotNil(t, input.PBoolOne, "PBoolOne must not be nil")
+		assert.False(t, *input.PBoolOne, "PBoolOne must be *false")
+		assert.Equal(t, (*bool)(nil), input.PBoolTwo, "PBoolTwo must be nil")
 		assert.DeepEqual(t, []string{"one", "two"}, input.Terms, "Terms must be parsed from multiple query params")
 		assert.DeepEqual(t, []float64{1.2, 3.5, 666.666}, input.Numbers, "Numbers must be parsed from multiple query params")
 		assert.DeepEqual(t, []string{"gzip", "deflate"}, input.Encoding, "Encoding must be parsed from multiple header params")

structs_test.go

@@ -16,6 +16,9 @@ type mockListRequest struct {
 	Terms    []string  `lambda:"query.terms"`
 	Numbers  []float64 `lambda:"query.numbers"`
 	Const    mockConst `lambda:"query.const"`
+	Bool     bool      `lambda:"query.bool"`
+	PBoolOne *bool     `lambda:"query.pbool1"`
+	PBoolTwo *bool     `lambda:"query.pbool2"`
 	Language string    `lambda:"header.Accept-Language"`
 	Encoding []string  `lambda:"header.Accept-Encoding"`
 }