fix: adding currency property

amplitude/client.go

@@ -154,6 +154,7 @@ func (c *client) Revenue(revenue Revenue, eventOptions EventOptions) {
 				constants.RevenueType:       revenue.RevenueType,
 				constants.RevenueReceipt:    revenue.Receipt,
 				constants.RevenueReceiptSig: revenue.ReceiptSig,
+				constants.Currency:          revenue.Currency,
 				constants.DefaultRevenue:    revenue.Revenue,
 			},
 		}

amplitude/client_test.go

@@ -159,6 +159,7 @@ func (t *ClientSuite) TestRevenue() {
 		Quantity:    45,
 		ProductID:   "product-1",
 		RevenueType: "revenue-1",
+		Currency:    "USD",
 		Receipt:     "receipt-1",
 		ReceiptSig:  "sig-1",
 		Revenue:     7,
@@ -172,6 +173,7 @@ func (t *ClientSuite) TestRevenue() {
     "ip": "IP 1",
     "city": "IP 1 city",
     "event_properties": {
+	  "$currency": "USD",
       "$price": 12.3,
       "$quantity": 45,
       "$productId": "product-1",

amplitude/constants/constants.go

@@ -20,6 +20,7 @@ const (
 	RevenueQuantity   = "$quantity"
 	RevenuePrice      = "$price"
 	RevenueType       = "$revenueType"
+	Currency          = "$currency"
 	RevenueReceipt    = "$receipt"
 	RevenueReceiptSig = "$receiptSig"
 	DefaultRevenue    = "$revenue"

amplitude/types/event_options.go

@@ -34,6 +34,7 @@ type EventOptions struct {
 	Price              float64            `json:"price,omitempty"`
 	Quantity           int                `json:"quantity,omitempty"`
 	Revenue            float64            `json:"revenue,omitempty"`
+	Currency           string             `json:"currency,omitempty"`
 	ProductID          string             `json:"productId,omitempty"`
 	RevenueType        string             `json:"revenueType,omitempty"`
 	EventID            int                `json:"event_id,omitempty"`

amplitude/types/revenue.go

@@ -5,6 +5,7 @@ type Revenue struct {
 	Quantity    int
 	ProductID   string
 	RevenueType string
+	Currency    string
 	Receipt     string
 	ReceiptSig  string
 	Properties  map[string]interface{}