fix(utils): accept json.Number in ToDecimal

.changeset/utils-todecimal-jsonnumber.md

@@ -0,0 +1,7 @@
+---
+"chainlink": patch
+---
+
+Teach `utils.ToDecimal` to convert `json.Number` so pipeline tasks that consume HTTP JSON payloads (ethabiencode, fluxmonitor, OCR data sources) no longer fail with "type json.Number cannot be converted to decimal.Decimal".
+
+#bugfix

core/utils/decimal.go

@@ -1,6 +1,7 @@
 package utils
 
 import (
+	"encoding/json"
 	"math"
 	"math/big"
 
@@ -14,6 +15,14 @@ import (
 // https://github.com/smartcontractkit/chainlink/pull/14841
 func ToDecimal(input any) (decimal.Decimal, error) {
 	switch v := input.(type) {
+	case json.Number:
+		// json.Number is what encoding/json returns when Decoder.UseNumber()
+		// has been set, which is how the pipeline parses HTTP / JSON payloads
+		// containing numeric values. Without this case any downstream task
+		// that receives a json.Number (e.g. ethabiencode with a uint256[]
+		// argument, fluxmonitor, OCR data sources) fails the conversion with
+		// "type json.Number cannot be converted to decimal.Decimal".
+		return decimal.NewFromString(string(v))
 	case string:
 		return decimal.NewFromString(v)
 	case int:

core/utils/decimal_test.go

@@ -1,6 +1,7 @@
 package utils
 
 import (
+	"encoding/json"
 	"math"
 	"math/big"
 	"testing"
@@ -46,6 +47,12 @@ func TestDecimal(t *testing.T) {
 		{math.NaN(), true},
 		{float32(math.NaN()), true},
 		{true, true},
+		// json.Number is produced by Decoder.UseNumber, which the pipeline
+		// uses when decoding JSON HTTP responses. Both integer and floating
+		// point forms have to be accepted; see #8504.
+		{json.Number("123"), false},
+		{json.Number("-1.1"), false},
+		{json.Number("not-a-number"), true},
 	}
 	for _, tc := range tt {
 		_, err := ToDecimal(tc.v)