Send empty VoteChoices instead of nil

client/client.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2022-2024 The Decred developers
+// Copyright (c) 2022-2025 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -66,8 +66,11 @@ func (c *Client) FeeAddress(ctx context.Context, req types.FeeAddressRequest,
 func (c *Client) PayFee(ctx context.Context, req types.PayFeeRequest,
 	commitmentAddr stdaddr.Address) (*types.PayFeeResponse, error) {
 
-	// TSpendPolicy and TreasuryPolicy are optional but must be an empty map
-	// rather than nil.
+	// VoteChoices, TSpendPolicy and TreasuryPolicy are optional but must be an
+	// empty map rather than nil.
+	if req.VoteChoices == nil {
+		req.VoteChoices = map[string]string{}
+	}
 	if req.TSpendPolicy == nil {
 		req.TSpendPolicy = map[string]string{}
 	}
@@ -119,8 +122,11 @@ func (c *Client) TicketStatus(ctx context.Context, req types.TicketStatusRequest
 func (c *Client) SetVoteChoices(ctx context.Context, req types.SetVoteChoicesRequest,
 	commitmentAddr stdaddr.Address) (*types.SetVoteChoicesResponse, error) {
 
-	// TSpendPolicy and TreasuryPolicy are optional but must be an empty map
-	// rather than nil.
+	// VoteChoices, TSpendPolicy and TreasuryPolicy are optional but must be an
+	// empty map rather than nil.
+	if req.VoteChoices == nil {
+		req.VoteChoices = map[string]string{}
+	}
 	if req.TSpendPolicy == nil {
 		req.TSpendPolicy = map[string]string{}
 	}

internal/webapi/binding_test.go

@@ -0,0 +1,114 @@
+package webapi
+
+import (
+	"testing"
+
+	"github.com/decred/vspd/types/v3"
+	"github.com/gin-gonic/gin/binding"
+)
+
+// TestGinJSONBinding does not test code in this package. It is a
+// characterization test to determine exactly how Gin handles JSON binding tags.
+func TestGinJSONBinding(t *testing.T) {
+	tests := map[string]struct {
+		req         []byte
+		expectedErr string
+	}{
+
+		"Filled arrays bind without error": {
+			req: []byte(`{
+				"timestamp":      12345,
+				"tickethash":     "hash",
+				"votechoices":    {"k": "v"},
+				"tspendpolicy":   {"k": "v"},
+				"treasurypolicy": {"k": "v"}
+			}`),
+			expectedErr: "",
+		},
+
+		"Array filled beyond max does not bind": {
+			req: []byte(`{
+				"timestamp":      12345,
+				"tickethash":     "hash",
+				"votechoices":    {"k": "v"},
+				"tspendpolicy":   {"k": "v"},
+				"treasurypolicy": {"k1": "v","k2": "v","k3": "v","k4": "v"}
+			}`),
+			expectedErr: "Key: 'SetVoteChoicesRequest.TreasuryPolicy' Error:Field validation for 'TreasuryPolicy' failed on the 'max' tag",
+		},
+
+		"Empty arrays bind without error": {
+			req: []byte(`{
+				"timestamp":      12345,
+				"tickethash":     "hash",
+				"votechoices":    {},
+				"tspendpolicy":   {},
+				"treasurypolicy": {}
+			}`),
+			expectedErr: "",
+		},
+
+		"Missing array with 'required' tag does not bind": {
+			req: []byte(`{
+				"timestamp":      12345,
+				"tickethash":     "hash",
+				"tspendpolicy":   {},
+				"treasurypolicy": {}
+			}`),
+			expectedErr: "Key: 'SetVoteChoicesRequest.VoteChoices' Error:Field validation for 'VoteChoices' failed on the 'required' tag",
+		},
+
+		"Missing array with 'max' tag binds without error": {
+			req: []byte(`{
+				"timestamp":      12345,
+				"tickethash":     "hash",
+				"votechoices":    {},
+				"treasurypolicy": {}
+			}`),
+			expectedErr: "",
+		},
+
+		"Null array with 'required' tag does not bind": {
+			req: []byte(`{
+				"timestamp":      12345,
+				"tickethash":     "hash",
+				"votechoices":    null,
+				"tspendpolicy":   {},
+				"treasurypolicy": {}
+			}`),
+			expectedErr: "Key: 'SetVoteChoicesRequest.VoteChoices' Error:Field validation for 'VoteChoices' failed on the 'required' tag",
+		},
+
+		"Null array with 'max' tag binds without error": {
+			req: []byte(`{
+				"timestamp":      12345,
+				"tickethash":     "hash",
+				"votechoices":    {},
+				"tspendpolicy":   null,
+				"treasurypolicy": {}
+			}`),
+			expectedErr: "",
+		},
+	}
+
+	for testName, test := range tests {
+		t.Run(testName, func(t *testing.T) {
+			err := binding.JSON.BindBody(test.req, &types.SetVoteChoicesRequest{})
+			if test.expectedErr == "" {
+				if err != nil {
+					t.Fatalf("unexpected error: %v", err)
+				}
+			} else {
+				if err == nil {
+					t.Fatalf("expected error but got none")
+				}
+				if err.Error() != test.expectedErr {
+					t.Fatalf("incorrect error, got %q expected %q",
+						err.Error(), test.expectedErr)
+				}
+			}
+
+		})
+	}
+
+}