json: encode nil args as empty params

json/client.go

@@ -24,8 +24,8 @@ import (
 type clientRequest struct {
 	// A String containing the name of the method to be invoked.
 	Method string `json:"method"`
-	// Object to pass as request parameter to the method.
-	Params [1]interface{} `json:"params"`
+	// Array of objects to pass as request parameters to the method.
+	Params []interface{} `json:"params"`
 	// The request id. This can be of any type. It is used to match the
 	// response with the request that it is replying to.
 	Id uint64 `json:"id"`
@@ -45,9 +45,13 @@ func EncodeClientRequest(method string, args interface{}) ([]byte, error) {
 		log.Fatal(err)
 	}
 
+	params := []interface{}{}
+	if args != nil {
+		params = []interface{}{args}
+	}
 	c := &clientRequest{
 		Method: method,
-		Params: [1]interface{}{args},
+		Params: params,
 		Id:     val.Uint64(),
 	}
 	return json.Marshal(c)

json/json_test.go

@@ -135,3 +135,33 @@ func TestServiceBeforeAfter(t *testing.T) {
 		t.Errorf("Expected after in context to be 'After is true', got %s", afterValue)
 	}
 }
+
+func TestEncodeClientRequestNilArgs(t *testing.T) {
+	buf, err := EncodeClientRequest("Service1.Ping", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got map[string]interface{}
+	if err := json.Unmarshal(buf, &got); err != nil {
+		t.Fatal(err)
+	}
+	params, ok := got["params"].([]interface{})
+	if !ok {
+		t.Fatalf("params want array, got %T %v", got["params"], got["params"])
+	}
+	if len(params) != 0 {
+		t.Fatalf("nil args should encode as empty params array, got %#v", params)
+	}
+
+	buf, err = EncodeClientRequest("Service1.Multiply", &Service1Request{A: 4, B: 2})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := json.Unmarshal(buf, &got); err != nil {
+		t.Fatal(err)
+	}
+	params, ok = got["params"].([]interface{})
+	if !ok || len(params) != 1 {
+		t.Fatalf("non-nil args should encode as a one-element array, got %#v", got["params"])
+	}
+}

v2/json/client.go

@@ -23,8 +23,8 @@ import (
 type clientRequest struct {
 	// A String containing the name of the method to be invoked.
 	Method string `json:"method"`
-	// Object to pass as request parameter to the method.
-	Params [1]interface{} `json:"params"`
+	// Array of objects to pass as request parameters to the method.
+	Params []interface{} `json:"params"`
 	// The request id. This can be of any type. It is used to match the
 	// response with the request that it is replying to.
 	Id uint64 `json:"id"`
@@ -44,9 +44,13 @@ func EncodeClientRequest(method string, args interface{}) ([]byte, error) {
 		log.Fatal(err)
 	}
 
+	params := []interface{}{}
+	if args != nil {
+		params = []interface{}{args}
+	}
 	c := &clientRequest{
 		Method: method,
-		Params: [1]interface{}{args},
+		Params: params,
 		Id:     val.Uint64(),
 	}
 	return json.Marshal(c)

v2/json/json_test.go

@@ -132,3 +132,33 @@ func TestClientNullResult(t *testing.T) {
 		t.Fatalf("Unexpected error: %s", err)
 	}
 }
+
+func TestEncodeClientRequestNilArgs(t *testing.T) {
+	buf, err := EncodeClientRequest("Service1.Ping", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got map[string]interface{}
+	if err := json.Unmarshal(buf, &got); err != nil {
+		t.Fatal(err)
+	}
+	params, ok := got["params"].([]interface{})
+	if !ok {
+		t.Fatalf("params want array, got %T %v", got["params"], got["params"])
+	}
+	if len(params) != 0 {
+		t.Fatalf("nil args should encode as empty params array, got %#v", params)
+	}
+
+	buf, err = EncodeClientRequest("Service1.Multiply", &Service1Request{A: 4, B: 2})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := json.Unmarshal(buf, &got); err != nil {
+		t.Fatal(err)
+	}
+	params, ok = got["params"].([]interface{})
+	if !ok || len(params) != 1 {
+		t.Fatalf("non-nil args should encode as a one-element array, got %#v", got["params"])
+	}
+}

v2/json2/client.go

@@ -27,7 +27,7 @@ type clientRequest struct {
 	Method string `json:"method"`
 
 	// Object to pass as request parameter to the method.
-	Params interface{} `json:"params"`
+	Params interface{} `json:"params,omitempty"`
 
 	// The request id. This can be of any type. It is used to match the
 	// response with the request that it is replying to.

v2/json2/json_test.go

@@ -289,3 +289,28 @@ func TestDecodeNullResult(t *testing.T) {
 		t.Error("Expected result to be nil, but got:", result)
 	}
 }
+
+func TestEncodeClientRequestNilArgs(t *testing.T) {
+	buf, err := EncodeClientRequest("Service1.Ping", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got map[string]interface{}
+	if err := json.Unmarshal(buf, &got); err != nil {
+		t.Fatal(err)
+	}
+	if _, ok := got["params"]; ok {
+		t.Fatalf("nil args should omit params, got %#v", got["params"])
+	}
+
+	buf, err = EncodeClientRequest("Service1.Multiply", &Service1Request{A: 4, B: 2})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := json.Unmarshal(buf, &got); err != nil {
+		t.Fatal(err)
+	}
+	if got["params"] == nil {
+		t.Fatal("non-nil args should include params")
+	}
+}