Inlined object fields (#108)

* Allow objects with single field to inline the field

* Test structs with private fields

* Added internal check

* Remove stale check

* Address compile error

schema/object.go

@@ -107,12 +107,18 @@ func (o *ObjectSchema) Properties() map[string]*PropertySchema {
 
 func (o *ObjectSchema) Unserialize(data any) (result any, err error) {
 	v := reflect.ValueOf(data)
+	var rawData map[string]any
 	if v.Kind() != reflect.Map {
-		return nil, &ConstraintError{
-			Message: fmt.Sprintf("Must be a map, %T given", data),
+		if len(o.Properties()) == 1 {
+			rawData, err = o.unserializeInlinedDataToMap(data)
+		} else {
+			return nil, &ConstraintError{
+				Message: fmt.Sprintf("Must be a map to convert to object, %T given", data),
+			}
 		}
+	} else {
+		rawData, err = o.convertData(v)
 	}
-	rawData, err := o.convertData(v)
 	if err != nil {
 		return nil, err
 	}
@@ -126,6 +132,26 @@ func (o *ObjectSchema) Unserialize(data any) (result any, err error) {
 	return rawData, nil
 }
 
+func (o *ObjectSchema) unserializeInlinedDataToMap(data any) (map[string]any, error) {
+	if len(o.Properties()) > 1 {
+		panic(fmt.Errorf("unserializeInlinedDataToMap called on ObjectSchema with %d"+
+			" properties; only 1 allowed", len(o.Properties())))
+	}
+	for fieldName, property := range o.Properties() {
+		unserializedProperty, err := property.Unserialize(data)
+		if err != nil {
+			return nil,
+				fmt.Errorf("error while unserializing single inlined property %s for object %s (%q);"+
+					"fix the property or specify the object as a map",
+					fieldName, o.ID(), err)
+		}
+		return map[string]any{
+			fieldName: unserializedProperty,
+		}, nil
+	}
+	panic("convertInlinedData called on object with zero properties")
+}
+
 func (o *ObjectSchema) unserializeToStruct(rawData map[string]any) (any, error) {
 	reflectType := reflect.TypeOf(o.defaultValue)
 	var reflectedValue reflect.Value

schema/object_test.go

@@ -2,6 +2,7 @@ package schema_test
 
 import (
 	"go.arcalot.io/assert"
+	"go.flow.arcalot.io/pluginsdk/schema/testdata"
 	"strconv"
 	"testing"
 
@@ -607,3 +608,83 @@ func TestObjectSchema_ValidateCompatibility(t *testing.T) {
 	assert.Error(t, s1.ValidateCompatibility(schema.NewStringEnumSchema(map[string]*schema.DisplayValue{})))
 	assert.Error(t, s1.ValidateCompatibility(schema.NewIntEnumSchema(map[int64]*schema.DisplayValue{}, nil)))
 }
+
+type testStructWithSingleField struct {
+	Field1 string `json:"field1"`
+}
+
+var testStructWithSingleFieldSchema = schema.NewStructMappedObjectSchema[testStructWithSingleField]("testStructWithSingleField", map[string]*schema.PropertySchema{
+	"field1": schema.NewPropertySchema(schema.NewStringSchema(nil, nil, nil),
+		schema.NewDisplayValue(schema.PointerTo("field1"), nil, nil),
+		true,
+		nil,
+		nil,
+		nil,
+		nil,
+		nil,
+	),
+})
+
+func TestUnserializeSingleFieldObject(t *testing.T) {
+	withoutInlineSerialized := map[string]any{
+		"field1": "hello",
+	}
+	expectedOutput := testStructWithSingleField{
+		"hello",
+	}
+
+	unserializedData, err := testStructWithSingleFieldSchema.Unserialize(withoutInlineSerialized)
+	assert.NoError(t, err)
+	assert.InstanceOf[testStructWithSingleField](t, unserializedData)
+	assert.Equals(t, unserializedData.(testStructWithSingleField), expectedOutput)
+}
+
+func TestUnserializeSingleFieldObjectInlined(t *testing.T) {
+	withoutInlineSerialized := "hello"
+
+	expectedOutput := testStructWithSingleField{
+		"hello",
+	}
+
+	unserializedData, err := testStructWithSingleFieldSchema.Unserialize(withoutInlineSerialized)
+	assert.NoError(t, err)
+	assert.InstanceOf[testStructWithSingleField](t, unserializedData)
+	assert.Equals(t, unserializedData.(testStructWithSingleField), expectedOutput)
+}
+
+func TestStructWithPrivateFields(t *testing.T) {
+	schemaForPrivateFieldStruct := schema.NewStructMappedObjectSchema[testdata.TestStructWithPrivateField](
+		"structWithPrivateField",
+		map[string]*schema.PropertySchema{
+			"field1": schema.NewPropertySchema(
+				schema.NewStringSchema(nil, nil, nil),
+				nil,
+				false,
+				nil,
+				nil,
+				nil,
+				schema.PointerTo("\"Hello world!\""),
+				nil,
+			),
+		},
+	)
+
+	inputWithOnlyPublicField := testdata.TestStructWithPrivateField{
+		Field1: "test",
+	}
+	serializedData, err := schemaForPrivateFieldStruct.Serialize(inputWithOnlyPublicField)
+	assert.NoError(t, err)
+	unserializedData, err := schemaForPrivateFieldStruct.Unserialize(serializedData)
+	assert.NoError(t, err)
+	assert.InstanceOf[testdata.TestStructWithPrivateField](t, unserializedData)
+	assert.Equals(t, inputWithOnlyPublicField, unserializedData.(testdata.TestStructWithPrivateField))
+
+	inputWithPrivateField := testdata.GetTestStructWithPrivateFieldPresent()
+	serializedData, err = schemaForPrivateFieldStruct.Serialize(inputWithPrivateField)
+	assert.NoError(t, err)
+	unserializedData, err = schemaForPrivateFieldStruct.Unserialize(serializedData)
+	assert.NoError(t, err)
+	assert.InstanceOf[testdata.TestStructWithPrivateField](t, unserializedData)
+	// The unserialization will only be able to fill in the public fields.
+	assert.Equals(t, inputWithOnlyPublicField, unserializedData.(testdata.TestStructWithPrivateField))
+}