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feature: nested json object parsing #43

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feature: nested json object parsing #43

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10 changes: 5 additions & 5 deletions pkg/plugin/datasource.go
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,7 @@ func (ds *MQTTDatasource) SubscribeStream(_ context.Context, req *backend.Subscr
func (ds *MQTTDatasource) RunStream(ctx context.Context, req *backend.RunStreamRequest, sender *backend.StreamSender) error {
ds.Client.Subscribe(req.Path)
defer ds.Client.Unsubscribe(req.Path)
fields := make(map[string]*data.Field)

for {
select {
Expand All @@ -126,7 +127,7 @@ func (ds *MQTTDatasource) RunStream(ctx context.Context, req *backend.RunStreamR
if message.Topic != req.Path {
continue
}
err := ds.SendMessage(message, req, sender)
err := ds.SendMessage(fields, message, req, sender)
if err != nil {
log.DefaultLogger.Error(fmt.Sprintf("unable to send message: %s", err.Error()))
}
Expand Down Expand Up @@ -162,7 +163,7 @@ func (ds *MQTTDatasource) Query(query backend.DataQuery) backend.DataResponse {
return response
}

frame := ToFrame(qm.Topic, messages)
frame := ToFrame(make(map[string]*data.Field), qm.Topic, messages)

if qm.Topic != "" {
frame.SetMeta(&data.FrameMeta{
Expand All @@ -173,8 +174,7 @@ func (ds *MQTTDatasource) Query(query backend.DataQuery) backend.DataResponse {
response.Frames = append(response.Frames, frame)
return response
}

func (ds *MQTTDatasource) SendMessage(msg mqtt.StreamMessage, req *backend.RunStreamRequest, sender *backend.StreamSender) error {
func (ds *MQTTDatasource) SendMessage(fields map[string]*data.Field, msg mqtt.StreamMessage, req *backend.RunStreamRequest, sender *backend.StreamSender) error {
if !ds.Client.IsSubscribed(req.Path) {
return nil
}
Expand All @@ -184,7 +184,7 @@ func (ds *MQTTDatasource) SendMessage(msg mqtt.StreamMessage, req *backend.RunSt
Value: msg.Value,
}

frame := ToFrame(msg.Topic, []mqtt.Message{message})
frame := ToFrame(fields, msg.Topic, []mqtt.Message{message})

log.DefaultLogger.Debug(fmt.Sprintf("Sending message to client for topic %s", msg.Topic))
return sender.SendFrame(frame, data.IncludeAll)
Expand Down
104 changes: 58 additions & 46 deletions pkg/plugin/message.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@ package plugin

import (
"encoding/json"
"fmt"
"sort"
"strconv"
"strings"
Expand All @@ -11,12 +10,12 @@ import (
"github.com/grafana/mqtt-datasource/pkg/mqtt"
)

func ToFrame(topic string, messages []mqtt.Message) *data.Frame {
func ToFrame(fields map[string]*data.Field, topic string, messages []mqtt.Message) *data.Frame {
count := len(messages)
if count > 0 {
first := messages[0].Value
if strings.HasPrefix(first, "{") {
return jsonMessagesToFrame(topic, messages)
return jsonMessagesToFrame(fields, topic, messages)
}
}

Expand All @@ -36,61 +35,74 @@ func ToFrame(topic string, messages []mqtt.Message) *data.Frame {
return data.NewFrame(topic, timeField, valueField)
}

func jsonMessagesToFrame(topic string, messages []mqtt.Message) *data.Frame {
count := len(messages)
if count == 0 {
return nil
// unnestMap recursively unwraps a given arbitrary map, thereby appending its concrete values under the resulting path.
func unnestMap(v interface{}, newmap map[string]interface{}, key string) map[string]interface{} {
switch v := v.(type) {
case map[string]interface{}: // Object
for k, val := range v {
unnestMap(val, newmap, key+"."+k)
}
case []interface{}: // Array
for newkey := 0; newkey < len(v); newkey++ {
newmap[key+"["+strconv.Itoa(newkey)+"]"] = v[newkey]
}
default: // Number (float64), String (string), Boolean (bool), Null (nil)
newmap[key] = v
}
return newmap

var body map[string]float64
err := json.Unmarshal([]byte(messages[0].Value), &body)
if err != nil {
frame := data.NewFrame(topic)
frame.AppendNotices(data.Notice{Severity: data.NoticeSeverityError,
Text: fmt.Sprintf("error unmarshalling json message: %s", err.Error()),
})
return frame
}

// changeMapStructure transforms a nested arbitrary map to a simple key value layout.
func changeMapStructure(nestedMap map[string]interface{}) map[string]interface{} {
newmap := make(map[string]interface{})
for k, v := range nestedMap {
newmap = unnestMap(v, newmap, k)
}
return newmap
}

func jsonMessagesToFrame(fields map[string]*data.Field, topic string, messages []mqtt.Message) *data.Frame {
count := len(messages)
if count == 0 {
return nil
}
timeField := data.NewFieldFromFieldType(data.FieldTypeTime, count)
timeField.Name = "Time"
timeField.SetConcrete(0, messages[0].Timestamp)

// Create a field for each key and set the first value
keys := make([]string, 0, len(body))
fields := make(map[string]*data.Field, len(body))
for key, val := range body {
field := data.NewFieldFromFieldType(data.FieldTypeNullableFloat64, count)
field.Name = key
field.SetConcrete(0, val)
fields[key] = field
keys = append(keys, key)
}
sort.Strings(keys) // keys stable field order.

// Add rows 1...n
for row, m := range messages {
if row == 0 {
continue
}

err := json.Unmarshal([]byte(m.Value), &body)
if err != nil {
continue // bad row?
}

timeField.SetConcrete(row, m.Timestamp)
for key, val := range body {
field, ok := fields[key]
if ok {
field.SetConcrete(row, val)
var body map[string]interface{}
if err := json.Unmarshal([]byte(m.Value), &body); err != nil {
return nil
}
for key, val := range changeMapStructure(body) {
var t data.FieldType
field, exists := fields[key]
switch val.(type) {
case float64:
t = data.FieldTypeNullableFloat64
case string:
t = data.FieldTypeNullableString
case bool:
t = data.FieldTypeNullableBool
default:
delete(fields, key)
continue
}
if !exists || field.Type() != t {
field = data.NewFieldFromFieldType(t, count)
field.Name = key
fields[key] = field
}
field.SetConcrete(row, val)
}
}

frame := data.NewFrame(topic, timeField)
for _, key := range keys {
frame.Fields = append(frame.Fields, fields[key])
for _, f := range fields {
frame.Fields = append(frame.Fields, f)
}
sort.Slice(frame.Fields, func(i, j int) bool {
return frame.Fields[i].Name < frame.Fields[j].Name
})
return frame
}
61 changes: 38 additions & 23 deletions pkg/plugin/message_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,14 @@ import (
"testing"
"time"

"github.com/grafana/grafana-plugin-sdk-go/data"
"github.com/grafana/mqtt-datasource/pkg/mqtt"
"github.com/grafana/mqtt-datasource/pkg/plugin"
"github.com/stretchr/testify/require"
)

func TestSimpleValueMessage(t *testing.T) {
frame := plugin.ToFrame("test/data", []mqtt.Message{
frame := plugin.ToFrame(make(map[string]*data.Field), "test/data", []mqtt.Message{
{
Timestamp: time.Unix(1, 0),
Value: "1",
Expand All @@ -24,31 +25,45 @@ func TestSimpleValueMessage(t *testing.T) {

func TestJSONValuesMessage(t *testing.T) {
timestamp := time.Unix(1, 0)
values := []float64{
-0.5182926829268293,
-0.3582317073170732,
values := []interface{}{
"-0.5182926829268293",
"Hi",
0.1753048780487805,
0.20599365234375,
false,
-0.050048828125,
1.03582763671875,
true,
}
msg := fmt.Sprintf(`{"ax": %v, "ay": %v, "az": %v, "gx": %v, "gy": %v, "gz": %v}`,
values[0], values[1], values[2], values[3], values[4], values[5])
frame := plugin.ToFrame("test/data", []mqtt.Message{
cases := []struct {
msg string
keys []string
}{
{
Timestamp: timestamp,
Value: msg,
},
})
numFields := len(values) + 1
require.NotNil(t, frame)
require.Equal(t, numFields, len(frame.Fields))
v, ok := frame.Fields[0].ConcreteAt(0)
require.Equal(t, true, ok)
require.Equal(t, v, timestamp)
for idx, val := range values {
v, err := frame.Fields[idx+1].FloatAt(0)
require.NoError(t, err)
require.Equal(t, val, v)
msg: fmt.Sprintf(`{"ax": %#v, "ay": %#v, "az": %#v, "gx": %#v, "gy": %#v, "gz": %#v}`,
values[0], values[1], values[2], values[3], values[4], values[5]),
keys: []string{"ax", "ay", "az", "gx", "gy", "gz"}},

{
msg: fmt.Sprintf(`{"ax": %#v, "ay":{"az": { "gx": %#v}, "gy": %#v}, "gz":{"b":{"bx": %#v,"by": %#v, "bz": %#v}}}`,
values[0], values[1], values[2], values[3], values[4], values[5]),
keys: []string{"ax", "ay.az.gx", "ay.gy", "gz.b.bx", "gz.b.by", "gz.b.bz"}},
}
for _, c := range cases {
frame := plugin.ToFrame(make(map[string]*data.Field), "test/data", []mqtt.Message{
{
Timestamp: timestamp,
Value: c.msg,
},
})
numFields := len(values) + 1
require.NotNil(t, frame)
require.Equal(t, numFields, len(frame.Fields))
v, ok := frame.Fields[0].ConcreteAt(0)
require.Equal(t, true, ok)
require.Equal(t, v, timestamp)
for idx, val := range values {
require.Equal(t, frame.Fields[idx+1].Name, c.keys[idx])
v, _ := frame.Fields[idx+1].ConcreteAt(0)
require.Equal(t, val, v)
}
}
}