allow omitempty struct

bootstrap/bootstrap.go

@@ -32,6 +32,7 @@ type Generator struct {
 	OmitEmpty                bool
 	DisallowUnknownFields    bool
 	SkipMemberNameUnescaping bool
+	AllowOmitEmptyStruct     bool
 
 	OutName       string
 	BuildTags     string
@@ -137,6 +138,9 @@ func (g *Generator) writeMain() (path string, err error) {
 	if g.SkipMemberNameUnescaping {
 		fmt.Fprintln(f, "  g.SkipMemberNameUnescaping()")
 	}
+	if g.AllowOmitEmptyStruct {
+		fmt.Fprintln(f, "  g.AllowOmitEmptyStruct()")
+	}
 
 	sort.Strings(g.Types)
 	for _, v := range g.Types {

easyjson/main.go

@@ -37,6 +37,7 @@ var processPkg = flag.Bool("pkg", false, "process the whole package instead of j
 var disallowUnknownFields = flag.Bool("disallow_unknown_fields", false, "return error if any unknown field in json appeared")
 var skipMemberNameUnescaping = flag.Bool("disable_members_unescape", false, "don't perform unescaping of member names to improve performance")
 var showVersion = flag.Bool("version", false, "print version and exit")
+var allowOmitEmptyStruct = flag.Bool("allow_omitempty_struct", false, "skip empty struct fields if omitempty tag is present")
 
 func generate(fname string) (err error) {
 	fInfo, err := os.Stat(fname)
@@ -85,6 +86,7 @@ func generate(fname string) (err error) {
 		NoStdMarshalers:          *noStdMarshalers,
 		DisallowUnknownFields:    *disallowUnknownFields,
 		SkipMemberNameUnescaping: *skipMemberNameUnescaping,
+		AllowOmitEmptyStruct:     *allowOmitEmptyStruct,
 		OmitEmpty:                *omitEmpty,
 		LeaveTemps:               *leaveTemps,
 		OutName:                  outName,

gen/encoder.go

@@ -306,6 +306,15 @@ func (g *Generator) notEmptyCheck(t reflect.Type, v string) string {
 	switch t.Kind() {
 	case reflect.Slice, reflect.Map:
 		return "len(" + v + ") != 0"
+	case reflect.Struct:
+		if g.allowOmitEmptyStruct {
+			val, s := reflect.New(t).Elem(), "false"
+			for i := 0; i < val.NumField(); i++ {
+				s += " || " + g.notEmptyCheck(val.Field(i).Type(), v+"."+t.Field(i).Name)
+			}
+			return s
+		}
+		return "true"
 	case reflect.Interface, reflect.Ptr:
 		return v + " != nil"
 	case reflect.Bool:
@@ -339,7 +348,11 @@ func (g *Generator) genStructFieldEncoder(t reflect.Type, f reflect.StructField,
 		fmt.Fprintln(g.out, "  {")
 		toggleFirstCondition = false
 	} else {
-		fmt.Fprintln(g.out, "  if", g.notEmptyCheck(f.Type, "in."+f.Name), "{")
+		fmt.Fprintln(
+			g.out, "  if",
+			strings.ReplaceAll(g.notEmptyCheck(f.Type, "in."+f.Name), "|| false", ""),
+			"{",
+		)
 		// can be any in runtime, so toggleFirstCondition stay as is
 	}
 

gen/generator.go

@@ -39,6 +39,7 @@ type Generator struct {
 	fieldNamer               FieldNamer
 	simpleBytes              bool
 	skipMemberNameUnescaping bool
+	allowOmitEmptyStruct     bool
 
 	// package path to local alias map for tracking imports
 	imports map[string]string
@@ -123,6 +124,11 @@ func (g *Generator) SkipMemberNameUnescaping() {
 	g.skipMemberNameUnescaping = true
 }
 
+// AllowOmitEmptyStruct instructs to allow struct field emptiness check if omitempty tag is provided.
+func (g *Generator) AllowOmitEmptyStruct() {
+	g.allowOmitEmptyStruct = true
+}
+
 // OmitEmpty triggers `json=",omitempty"` behaviour by default.
 func (g *Generator) OmitEmpty() {
 	g.omitEmpty = true