fix(exiftool): convert interface{} array to string array

pkg/modules/exiftool/exiftool.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"reflect"
 
 	"github.com/barasher/go-exiftool"
 	"go.uber.org/zap"
@@ -109,6 +110,17 @@ func (engine *ExifTool) WriteMetadata(ctx context.Context, logger *zap.Logger, m
 			fileMetadata[0].SetString(key, val)
 		case []string:
 			fileMetadata[0].SetStrings(key, val)
+		case []interface{}:
+			// See https://github.com/gotenberg/gotenberg/issues/1048.
+			strings := make([]string, len(val))
+			for i, entry := range val {
+				if str, ok := entry.(string); ok {
+					strings[i] = str
+					continue
+				}
+				return fmt.Errorf("write PDF metadata with ExifTool: %s %+v %s %w", key, val, reflect.TypeOf(val), gotenberg.ErrPdfEngineMetadataValueNotSupported)
+			}
+			fileMetadata[0].SetStrings(key, strings)
 		case bool:
 			fileMetadata[0].SetString(key, fmt.Sprintf("%t", val))
 		case int:
@@ -122,7 +134,7 @@ func (engine *ExifTool) WriteMetadata(ctx context.Context, logger *zap.Logger, m
 		// TODO: support more complex cases, e.g., arrays and nested objects
 		// 	(limitations in underlying library).
 		default:
-			return fmt.Errorf("write PDF metadata with ExifTool: %w", gotenberg.ErrPdfEngineMetadataValueNotSupported)
+			return fmt.Errorf("write PDF metadata with ExifTool: %s %+v %s %w", key, val, reflect.TypeOf(val), gotenberg.ErrPdfEngineMetadataValueNotSupported)
 		}
 	}
 

pkg/modules/exiftool/exiftool_test.go

@@ -162,7 +162,20 @@ func TestExiftool_WriteMetadata(t *testing.T) {
 			expectError: true,
 		},
 		{
-			scenario:   "gotenberg.ErrPdfEngineMetadataValueNotSupported",
+			scenario:   "gotenberg.ErrPdfEngineMetadataValueNotSupported (not string array)",
+			createCopy: true,
+			inputPath:  "/tests/test/testdata/pdfengines/sample1.pdf",
+			metadata: map[string]interface{}{
+				"Unsupported": []interface{}{
+					"foo",
+					1,
+				},
+			},
+			expectError:   true,
+			expectedError: gotenberg.ErrPdfEngineMetadataValueNotSupported,
+		},
+		{
+			scenario:   "gotenberg.ErrPdfEngineMetadataValueNotSupported (default)",
 			createCopy: true,
 			inputPath:  "/tests/test/testdata/pdfengines/sample1.pdf",
 			metadata: map[string]interface{}{
@@ -171,6 +184,24 @@ func TestExiftool_WriteMetadata(t *testing.T) {
 			expectError:   true,
 			expectedError: gotenberg.ErrPdfEngineMetadataValueNotSupported,
 		},
+		{
+			scenario:   "success (interface array to string array)",
+			createCopy: true,
+			inputPath:  "/tests/test/testdata/pdfengines/sample1.pdf",
+			metadata: map[string]interface{}{
+				"Keywords": []interface{}{
+					"first",
+					"second",
+				},
+			},
+			expectMetadata: map[string]interface{}{
+				"Keywords": []interface{}{
+					"first",
+					"second",
+				},
+			},
+			expectError: false,
+		},
 		{
 			scenario:   "success",
 			createCopy: true,