Move use of gjson into jsonutil.

go.mod

@@ -34,6 +34,7 @@ require (
 	github.com/rs/cors v1.11.0
 	github.com/spf13/viper v1.12.0
 	github.com/stretchr/testify v1.8.1
+	github.com/tidwall/gjson v1.17.1
 	github.com/vrischmann/go-metrics-influxdb v0.1.1
 	github.com/xeipuuv/gojsonschema v1.2.0
 	github.com/yudai/gojsondiff v1.0.0
@@ -70,7 +71,6 @@ require (
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/stretchr/objx v0.5.0 // indirect
 	github.com/subosito/gotenv v1.3.0 // indirect
-	github.com/tidwall/gjson v1.17.1 // indirect
 	github.com/tidwall/match v1.1.1 // indirect
 	github.com/tidwall/pretty v1.2.0 // indirect
 	github.com/tidwall/sjson v1.2.5 // indirect

openrtb_ext/request_wrapper.go

@@ -9,7 +9,6 @@ import (
 	"github.com/prebid/openrtb/v20/openrtb2"
 	"github.com/prebid/prebid-server/v3/util/jsonutil"
 	"github.com/prebid/prebid-server/v3/util/ptrutil"
-	"github.com/tidwall/gjson"
 )
 
 // RequestWrapper wraps the OpenRTB request to provide a storage location for unmarshalled ext fields, so they
@@ -1279,11 +1278,7 @@ func (re *RegExt) unmarshal(extJson json.RawMessage) error {
 
 	gpcJson, hasGPC := re.ext[gpcKey]
 	if hasGPC && gpcJson != nil {
-		gpcResult := gjson.ParseBytes(gpcJson)
-		if gpcResult.Exists() {
-			gpc := gpcResult.String()
-			re.gpc = &gpc
-		}
+		jsonutil.ParseIntoString(gpcJson, &re.gpc)
 	}
 
 	return nil

util/jsonutil/forcestring.go

@@ -0,0 +1,15 @@
+package jsonutil
+
+import "github.com/tidwall/gjson"
+
+// ParseIntoString Parse json bytes into a string pointer
+func ParseIntoString(b []byte, ppString **string) {
+	if ppString == nil {
+		panic("ppString is nil")
+	}
+	result := gjson.ParseBytes(b)
+	if result.Exists() && result.Raw != `null` {
+		*ppString = new(string)
+		**ppString = result.String()
+	}
+}

util/jsonutil/forcestring_test.go

@@ -0,0 +1,57 @@
+package jsonutil
+
+import (
+	"testing"
+
+	"github.com/prebid/prebid-server/v3/util/ptrutil"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_ParseIntoString(t *testing.T) {
+	tests := []struct {
+		name string
+		b    []byte
+		want *string
+	}{
+		{
+			name: "empty",
+		},
+		{
+			name: "quoted_1",
+			b:    []byte(`"1"`),
+			want: ptrutil.ToPtr("1"),
+		},
+		{
+			name: "unquoted_1",
+			b:    []byte(`1`),
+			want: ptrutil.ToPtr("1"),
+		},
+		{
+			name: "null",
+			b:    []byte(`null`),
+		},
+		{
+			name: "quoted_null",
+			b:    []byte(`"null"`),
+			want: ptrutil.ToPtr("null"),
+		},
+		{
+			name: "quoted_hello",
+			b:    []byte(`"hello"`),
+			want: ptrutil.ToPtr("hello"),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var got *string
+			ParseIntoString(tt.b, &got)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func Test_ParseIntoStringPanic(t *testing.T) {
+	assert.Panics(t, func() {
+		ParseIntoString([]byte(`"123"`), nil)
+	})
+}