Allow missing and null pointer fields to be nil.

swbemservices.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package wmi

swbemservices_test.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package wmi
@@ -103,8 +104,8 @@ func WbemGetMemoryUsageMB(s *SWbemServices) (float64, float64, float64) {
 //Run all benchmarks (should run for at least 60s to get a stable number):
 //go test -run=NONE -bench=Version -benchtime=120s
 
-//Individual benchmarks:
-//go test -run=NONE -bench=NewVersion -benchtime=120s
+// Individual benchmarks:
+// go test -run=NONE -bench=NewVersion -benchtime=120s
 func BenchmarkNewVersion(b *testing.B) {
 	s, err := InitializeSWbemServices(DefaultClient)
 	if err != nil {
@@ -128,7 +129,7 @@ func BenchmarkNewVersion(b *testing.B) {
 	}
 }
 
-//go test -run=NONE -bench=OldVersion -benchtime=120s
+// go test -run=NONE -bench=OldVersion -benchtime=120s
 func BenchmarkOldVersion(b *testing.B) {
 	var dst []Win32_OperatingSystem
 	q := CreateQuery(&dst, "")

wmi.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 /*
@@ -20,7 +21,6 @@ Example code to print names of running processes:
 			println(i, v.Name)
 		}
 	}
-
 */
 package wmi
 
@@ -338,11 +338,6 @@ func (c *Client) loadEntity(dst interface{}, src *ole.IDispatch) (errFieldMismat
 		f := v.Field(i)
 		of := f
 		isPtr := f.Kind() == reflect.Ptr
-		if isPtr {
-			ptr := reflect.New(f.Type().Elem())
-			f.Set(ptr)
-			f = f.Elem()
-		}
 		n := v.Type().Field(i).Name
 		if n[0] < 'A' || n[0] > 'Z' {
 			continue
@@ -367,6 +362,12 @@ func (c *Client) loadEntity(dst interface{}, src *ole.IDispatch) (errFieldMismat
 		}
 		defer prop.Clear()
 
+		if isPtr && !(c.PtrNil && prop.VT == 0x1) {
+			ptr := reflect.New(f.Type().Elem())
+			f.Set(ptr)
+			f = f.Elem()
+		}
+
 		if prop.VT == 0x1 { //VT_NULL
 			continue
 		}

wmi_test.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package wmi
@@ -39,6 +40,87 @@ func TestFieldMismatch(t *testing.T) {
 	}
 }
 
+func TestMissingFields(t *testing.T) {
+	type s struct {
+		Name           string
+		Missing        uint32
+		MissingPointer *uint32
+	}
+
+	var dst []s
+
+	client := &Client{
+		AllowMissingFields: true,
+	}
+	err := client.Query("SELECT Name FROM Win32_Process", &dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i := range dst {
+		if dst[i].Missing != 0 {
+			t.Fatal("Expected Missing field to be 0")
+		}
+		if dst[i].MissingPointer != nil {
+			t.Fatal("Expected MissingPointer field to be nil")
+		}
+	}
+
+	// NonePtrZero and PtrNil should only affect the behavior of fields that
+	// exist as result properties, not missing fields.
+	client = &Client{
+		NonePtrZero:        true,
+		PtrNil:             true,
+		AllowMissingFields: true,
+	}
+	dst = []s{}
+	err = client.Query("SELECT Name FROM Win32_Process", &dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i := range dst {
+		if dst[i].Missing != 0 {
+			t.Fatal("Expected Missing field to be 0")
+		}
+		if dst[i].MissingPointer != nil {
+			t.Fatal("Expected MissingPointer field to be nil")
+		}
+	}
+}
+
+func TestNullPointerField(t *testing.T) {
+	type s struct {
+		Name   string
+		Status *string
+	}
+
+	var dst []s
+
+	client := &Client{}
+	err := client.Query("SELECT Name, Status FROM Win32_Process WHERE Status IS NULL", &dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i := range dst {
+		if dst[i].Status == nil {
+			t.Fatal("Expected Status field to not be nil")
+		}
+	}
+
+	client = &Client{
+		PtrNil: true,
+	}
+	dst = []s{}
+	err = client.Query("SELECT Name, Status FROM Win32_Process WHERE Status IS NULL", &dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i := range dst {
+		if dst[i].Status != nil {
+			t.Fatal("Expected Status field to be nil")
+		}
+	}
+}
+
 func TestStrings(t *testing.T) {
 	printed := false
 	f := func() {