fix: Provided custom XML marshaling of Event

models/event.go

@@ -16,6 +16,9 @@ package models
 
 import (
 	"encoding/json"
+	"encoding/xml"
+	"fmt"
+	"strings"
 
 	"github.com/fxamacker/cbor/v2"
 )
@@ -29,7 +32,7 @@ type Event struct {
 	Modified    int64             `json:"modified,omitempty" codec:"modified,omitempty"` // Modified is a timestamp indicating when the event was last modified.
 	Origin      int64             `json:"origin,omitempty" codec:"origin,omitempty"`     // Origin is a timestamp that can communicate the time of the original reading, prior to event creation
 	Readings    []Reading         `json:"readings,omitempty" codec:"readings,omitempty"` // Readings will contain zero to many entries for the associated readings of a given event.
-	Tags        map[string]string `json:"tags,omitempty" codec:"tags,omitempty"`         // Tags is an optional collection of key/value pairs that all the event to be tagged with custom information.
+	Tags        map[string]string `json:"tags,omitempty" codec:"tags,omitempty" xml:"-"` // Tags is an optional collection of key/value pairs that all the event to be tagged with custom information. Ignored for XML since maps not supported.
 	isValidated bool              // internal member used for validation check
 }
 
@@ -109,3 +112,26 @@ func (e Event) CBOR() []byte {
 
 	return cbor
 }
+
+// ToXML provides a XML representation of the Event as a string
+func (e Event) ToXML() (string, error) {
+	eventXml, err := xml.Marshal(e)
+	if err != nil {
+		return "", err
+	}
+
+	// The Tags field is being ignore from XML Marshaling since maps are not supported.
+	// We have to provide our own marshaling of the Tags field if it is non-empty
+	if len(e.Tags) > 0 {
+		tagsXmlElements := []string{"<Tags>"}
+		for key, value := range e.Tags {
+			tag := fmt.Sprintf("<%s>%s</%s>", key, value, key)
+			tagsXmlElements = append(tagsXmlElements, tag)
+		}
+		tagsXmlElements = append(tagsXmlElements, "</Tags>")
+		tagsXml := strings.Join(tagsXmlElements, "")
+		eventXml = []byte(strings.Replace(string(eventXml), "</Event>", tagsXml+"</Event>", 1))
+	}
+
+	return string(eventXml), nil
+}

models/event_test.go

@@ -15,12 +15,13 @@
 package models
 
 import (
+	"fmt"
 	"reflect"
 	"strconv"
 	"testing"
 
 	"github.com/fxamacker/cbor/v2"
-	"github.com/go-playground/assert/v2"
+	"github.com/stretchr/testify/assert"
 )
 
 var TestEvent = Event{
@@ -32,6 +33,8 @@ var TestEvent = Event{
 	Readings: []Reading{TestReading},
 	Tags: map[string]string{
 		"GatewayID": "Houston-0001",
+		"Latitude":  "29.630771",
+		"Longitude": "-95.377603",
 	},
 }
 
@@ -48,8 +51,12 @@ func TestEvent_String(t *testing.T) {
 				",\"modified\":" + strconv.FormatInt(TestEvent.Modified, 10) +
 				",\"origin\":" + strconv.FormatInt(TestEvent.Origin, 10) +
 				",\"readings\":[" + TestReading.String() + "]" +
-				",\"tags\":{\"GatewayID\":\"Houston-0001\"}" +
-				"}"},
+				",\"tags\":{" +
+				"\"GatewayID\":\"Houston-0001\"" +
+				",\"Latitude\":\"29.630771\"" +
+				",\"Longitude\":\"-95.377603\"}" +
+				"}",
+		},
 		{"event to string, empty", Event{}, testEmptyJSON},
 	}
 	for _, tt := range tests {
@@ -93,3 +100,18 @@ func Test_encodeAsCBOR(t *testing.T) {
 		t.Error("Failed to properly decode event")
 	}
 }
+
+func TestEvent_ToXML(t *testing.T) {
+	// Since the order in map is random we have to verify the individual items exists without depending on order
+	contains := []string{
+		"<Event><ID></ID><Pushed>123</Pushed><Device>test device name</Device><Created>123</Created><Modified>123</Modified><Origin>123</Origin><Readings><Id>Thermometer</Id><Pushed>123</Pushed><Created>123</Created><Origin>123</Origin><Modified>123</Modified><Device>test device name</Device><Name>Temperature</Name><Value>45</Value><ValueType>Int16</ValueType><FloatEncoding>float16</FloatEncoding><BinaryValue>�</BinaryValue><MediaType>application/cbor</MediaType></Readings><Tags>",
+		"<GatewayID>Houston-0001</GatewayID>",
+		"<Latitude>29.630771</Latitude>",
+		"<Longitude>-95.377603</Longitude>",
+		"</Tags></Event>",
+	}
+	actual, _ := TestEvent.ToXML()
+	for _, item := range contains {
+		assert.Contains(t, actual, item, fmt.Sprintf("Missing item '%s'", item))
+	}
+}

v2/dtos/event.go

@@ -6,6 +6,10 @@
 package dtos
 
 import (
+	"encoding/xml"
+	"fmt"
+	"strings"
+
 	v2 "github.com/edgexfoundry/go-mod-core-contracts/v2"
 	"github.com/edgexfoundry/go-mod-core-contracts/v2/dtos/common"
 	"github.com/edgexfoundry/go-mod-core-contracts/v2/models"
@@ -22,7 +26,7 @@ type Event struct {
 	Created            int64             `json:"created"`
 	Origin             int64             `json:"origin" validate:"required"`
 	Readings           []BaseReading     `json:"readings" validate:"gt=0,dive,required"`
-	Tags               map[string]string `json:"tags,omitempty"`
+	Tags               map[string]string `json:"tags,omitempty" xml:"-"` // Have to ignore since map not supported for XML
 }
 
 func FromEventModelToDTO(event models.Event) Event {
@@ -47,3 +51,26 @@ func FromEventModelToDTO(event models.Event) Event {
 		Tags:        tags,
 	}
 }
+
+// ToXML provides a XML representation of the Event as a string
+func (e Event) ToXML() (string, error) {
+	eventXml, err := xml.Marshal(e)
+	if err != nil {
+		return "", err
+	}
+
+	// The Tags field is being ignore from XML Marshaling since maps are not supported.
+	// We have to provide our own marshaling of the Tags field if it is non-empty
+	if len(e.Tags) > 0 {
+		tagsXmlElements := []string{"<Tags>"}
+		for key, value := range e.Tags {
+			tag := fmt.Sprintf("<%s>%s</%s>", key, value, key)
+			tagsXmlElements = append(tagsXmlElements, tag)
+		}
+		tagsXmlElements = append(tagsXmlElements, "</Tags>")
+		tagsXml := strings.Join(tagsXmlElements, "")
+		eventXml = []byte(strings.Replace(string(eventXml), "</Event>", tagsXml+"</Event>", 1))
+	}
+
+	return string(eventXml), nil
+}

v2/dtos/event_test.go

@@ -6,6 +6,7 @@
 package dtos
 
 import (
+	"fmt"
 	"testing"
 
 	v2 "github.com/edgexfoundry/go-mod-core-contracts/v2"
@@ -15,29 +16,34 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestFromEventModelToDTO(t *testing.T) {
-	valid := models.Event{
-		Id:         TestUUID,
-		Pushed:     TestTimestamp,
-		DeviceName: TestDeviceName,
-		Created:    TestTimestamp,
-		Origin:     TestTimestamp,
-		Tags: map[string]string{
-			"GatewayID": "Houston-0001",
-		},
-	}
-	expectedDTO := Event{
-		Versionable: common.Versionable{ApiVersion: v2.ApiVersion},
-		ID:          TestUUID,
-		Pushed:      TestTimestamp,
-		DeviceName:  TestDeviceName,
-		Created:     TestTimestamp,
-		Origin:      TestTimestamp,
-		Tags: map[string]string{
-			"GatewayID": "Houston-0001",
-		},
-	}
+var valid = models.Event{
+	Id:         TestUUID,
+	Pushed:     TestTimestamp,
+	DeviceName: TestDeviceName,
+	Created:    TestTimestamp,
+	Origin:     TestTimestamp,
+	Tags: map[string]string{
+		"GatewayID": "Houston-0001",
+		"Latitude":  "29.630771",
+		"Longitude": "-95.377603",
+	},
+}
+
+var expectedDTO = Event{
+	Versionable: common.Versionable{ApiVersion: v2.ApiVersion},
+	ID:          TestUUID,
+	Pushed:      TestTimestamp,
+	DeviceName:  TestDeviceName,
+	Created:     TestTimestamp,
+	Origin:      TestTimestamp,
+	Tags: map[string]string{
+		"GatewayID": "Houston-0001",
+		"Latitude":  "29.630771",
+		"Longitude": "-95.377603",
+	},
+}
 
+func TestFromEventModelToDTO(t *testing.T) {
 	tests := []struct {
 		name  string
 		event models.Event
@@ -51,3 +57,18 @@ func TestFromEventModelToDTO(t *testing.T) {
 		})
 	}
 }
+
+func TestEvent_ToXML(t *testing.T) {
+	// Since the order in map is random we have to verify the individual items exists without depending on order
+	contains := []string{
+		"<Event><ApiVersion>v2</ApiVersion><ID>7a1707f0-166f-4c4b-bc9d-1d54c74e0137</ID><Pushed>1594963842</Pushed><DeviceName>TestDevice</DeviceName><Created>1594963842</Created><Origin>1594963842</Origin><Tags>",
+		"<GatewayID>Houston-0001</GatewayID>",
+		"<Latitude>29.630771</Latitude>",
+		"<Longitude>-95.377603</Longitude>",
+		"</Tags></Event>",
+	}
+	actual, _ := expectedDTO.ToXML()
+	for _, item := range contains {
+		assert.Contains(t, actual, item, fmt.Sprintf("Missing item '%s'", item))
+	}
+}