[sdk/go] Support maps in Invoke outputs and Read inputs (#6014)

* [sdk/go] Support maps in Invoke outputs and Read inputs

These are already supported by the implementation, but were prevented by overzealous input validation in Invoke and ReadResource.

Follow-up to #4522 and #4521.

* Add CHANGELOG

* PR feedback

CHANGELOG.md

@@ -22,6 +22,9 @@ CHANGELOG
   give the user some information on how to resolve the problem
   [#6044](https://github.com/pulumi/pulumi/pull/6044)
 
+- [sdk/go] Support maps in Invoke outputs and Read inputs
+  [#6014](https://github.com/pulumi/pulumi/pull/6014)
+
 ## 2.16.2 (2020-12-23)
 
 - Fix a bug in the core engine that could cause previews to fail if a resource with changes had

sdk/go/pulumi/context.go

@@ -171,8 +171,10 @@ func (ctx *Context) Invoke(tok string, args interface{}, result interface{}, opt
 	}
 
 	resultV := reflect.ValueOf(result)
-	if resultV.Kind() != reflect.Ptr || resultV.Elem().Kind() != reflect.Struct {
-		return errors.New("result must be a pointer to a struct value")
+	if !(resultV.Kind() == reflect.Ptr &&
+		(resultV.Elem().Kind() == reflect.Struct ||
+			(resultV.Elem().Kind() == reflect.Map && resultV.Elem().Type().Key().Kind() == reflect.String))) {
+		return errors.New("result must be a pointer to a struct or map value")
 	}
 
 	options := &invokeOptions{}
@@ -305,8 +307,9 @@ func (ctx *Context) ReadResource(
 		if propsType.Kind() == reflect.Ptr {
 			propsType = propsType.Elem()
 		}
-		if propsType.Kind() != reflect.Struct {
-			return errors.New("props must be a struct or a pointer to a struct")
+		if !(propsType.Kind() == reflect.Struct ||
+			(propsType.Kind() == reflect.Map && propsType.Key().Kind() == reflect.String)) {
+			return errors.New("props must be a struct or map or a pointer to a struct or map")
 		}
 	}
 

sdk/go/pulumi/run_test.go

@@ -176,6 +176,7 @@ func TestReadResource(t *testing.T) {
 	}
 
 	err := RunErr(func(ctx *Context) error {
+		// Test struct-tag-based marshaling.
 		var res testResource2
 		err := ctx.ReadResource("test:resource:type", "resA", ID("someID"), &testResource2Inputs{
 			Foo: String("oof"),
@@ -203,6 +204,20 @@ func TestReadResource(t *testing.T) {
 		assert.Equal(t, []Resource{&res}, deps)
 		assert.Equal(t, "qux", foo)
 
+		// Test map marshaling.
+		var res2 testResource2
+		err = ctx.ReadResource("test:resource:type", "resA", ID("someID"), Map{
+			"foo": String("oof"),
+		}, &res2)
+		assert.NoError(t, err)
+
+		foo, known, secret, deps, err = await(res2.Foo)
+		assert.NoError(t, err)
+		assert.True(t, known)
+		assert.False(t, secret)
+		assert.Equal(t, []Resource{&res2}, deps)
+		assert.Equal(t, "qux", foo)
+
 		return nil
 	}, WithMocks("project", "stack", mocks))
 	assert.NoError(t, err)
@@ -224,16 +239,26 @@ func TestInvoke(t *testing.T) {
 	}
 
 	err := RunErr(func(ctx *Context) error {
+		// Test struct unmarshaling.
 		var result invokeResult
 		err := ctx.Invoke("test:index:func", &invokeArgs{
 			Bang: "gnab",
 			Bar:  "rab",
 		}, &result)
-
 		assert.NoError(t, err)
 		assert.Equal(t, "oof", result.Foo)
 		assert.Equal(t, "zab", result.Baz)
 
+		// Test map unmarshaling.
+		var result2 map[string]interface{}
+		err = ctx.Invoke("test:index:func", &invokeArgs{
+			Bang: "gnab",
+			Bar:  "rab",
+		}, &result2)
+		assert.NoError(t, err)
+		assert.Equal(t, "oof", result2["foo"].(string))
+		assert.Equal(t, "zab", result2["baz"].(string))
+
 		return nil
 	}, WithMocks("project", "stack", mocks))
 	assert.NoError(t, err)