pkg/aflow: support for optional tool args

Author: dvyukov

pkg/aflow/schema.go

@@ -9,6 +9,7 @@ import (
 	"iter"
 	"maps"
 	"reflect"
+	"strings"
 
 	"github.com/google/jsonschema-go/jsonschema"
 )
@@ -62,6 +63,10 @@ func convertFromMap[T any](m map[string]any, strict, tool bool) (T, error) {
 	for name, field := range foreachField(&val) {
 		f, ok := m[name]
 		if !ok {
+			fieldType, _ := reflect.TypeFor[T]().FieldByName(name)
+			if strings.Contains(fieldType.Tag.Get("json"), ",omitempty") {
+				continue
+			}
 			if tool {
 				return val, BadCallError(fmt.Sprintf("missing argument %q", name))
 			} else {

pkg/aflow/schema_test.go

@@ -79,10 +79,10 @@ func TestConvertFromMap(t *testing.T) {
 	testConvertFromMap(t, true, map[string]any{
 		"I1": 2.0,
 	}, struct {
-		I0 int
+		I0 int `json:"I0"`
 	}{},
 		`missing argument "I0"`,
-		`field "I0" is not present when converting map to struct { I0 int }`)
+		`field "I0" is not present when converting map to struct { I0 int "json:\"I0\"" }`)
 
 	testConvertFromMap(t, true, map[string]any{
 		"I0": "foo",
@@ -108,6 +108,14 @@ func TestConvertFromMap(t *testing.T) {
 	}{},
 		`unused fields when converting map to struct { I0 int }: map[I1:2]`,
 		`unused fields when converting map to struct { I0 int }: map[I1:2]`)
+
+	testConvertFromMap(t, false, map[string]any{
+		"I1": 2.0,
+	}, struct {
+		I0 int `json:",omitempty"`
+	}{},
+		``,
+		``)
 }
 
 func testConvertFromMap[T any](t *testing.T, strict bool, input map[string]any, output T, toolErr, nonToolErr string) {