fix(message): use correct encodings for JSON Number values (#281)

message/message.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"math"
 	"strings"
 	"unicode/utf8"
 
@@ -366,6 +367,16 @@ func setValue(json []byte, key string, value interface{}) ([]byte, error) {
 			return sjson.SetBytes(json, key, base64.Encode(v))
 		}
 	case Value:
+		// JSON number values can lose precision if not read with the right encoding.
+		// Determine if the value is an integer by checking if floating poit truncation has no
+		// affect of the value.
+		if v.gjson.Type == gjson.Number {
+			if v.Float() == math.Trunc(v.Float()) {
+				return sjson.SetBytes(json, key, v.Int())
+			}
+			return sjson.SetBytes(json, key, v.Float())
+		}
+
 		return sjson.SetBytes(json, key, v.Value())
 	default:
 		return sjson.SetBytes(json, key, v)

transform/object_copy_test.go

@@ -32,6 +32,36 @@ var objectCopyTests = []struct {
 			[]byte(`{"a":"b","c":"b"}`),
 		},
 	},
+	{
+		"large integer",
+		config.Config{
+			Settings: map[string]interface{}{
+				"object": map[string]interface{}{
+					"source_key": "a",
+					"target_key": "b",
+				},
+			},
+		},
+		[]byte(`{"a":30400402455622563}`),
+		[][]byte{
+			[]byte(`{"a":30400402455622563,"b":30400402455622563}`),
+		},
+	},
+	{
+		"large float",
+		config.Config{
+			Settings: map[string]interface{}{
+				"object": map[string]interface{}{
+					"source_key": "a",
+					"target_key": "b",
+				},
+			},
+		},
+		[]byte(`{"a":3.141592653589793}`),
+		[][]byte{
+			[]byte(`{"a":3.141592653589793,"b":3.141592653589793}`),
+		},
+	},
 	{
 		"unescape object",
 		config.Config{