add processor to pull field out of struct

internal/processor/struct-field-get.go

@@ -0,0 +1,49 @@
+package processor
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"reflect"
+
+	"github.com/jwetzell/showbridge-go/internal/config"
+)
+
+type StructFieldGet struct {
+	config config.ProcessorConfig
+	Name   string
+}
+
+func (sf *StructFieldGet) Process(ctx context.Context, payload any) (any, error) {
+	s := reflect.ValueOf(payload)
+
+	if s.Kind() != reflect.Struct {
+		return nil, errors.New("struct.field.get processor only accepts a struct payload")
+	}
+
+	field := s.FieldByName(sf.Name)
+	if !field.IsValid() {
+		return nil, fmt.Errorf("struct.field.get field '%s' does not exist", sf.Name)
+	}
+
+	return field.Interface(), nil
+}
+
+func (sf *StructFieldGet) Type() string {
+	return sf.config.Type
+}
+
+func init() {
+	RegisterProcessor(ProcessorRegistration{
+		Type: "struct.field.get",
+		New: func(config config.ProcessorConfig) (Processor, error) {
+			params := config.Params
+			nameString, err := params.GetString("name")
+			if err != nil {
+				return nil, fmt.Errorf("struct.field.get name error: %w", err)
+			}
+
+			return &StructFieldGet{config: config, Name: nameString}, nil
+		},
+	})
+}