#399

backend/app/services/post_import_previewer.rb

@@ -126,7 +126,7 @@ class PostImportPreviewer
 
     warnings_present = field_warnings.values.any?(&:present?) || base_warnings.present?
     { source_row: row[:source_row],
-      url: normal_url || url,
+      url: validation_errors[:url].present? ? url : (normal_url || url),
       attributes:,
       provenance:,
       tag_sources:,
@@ -199,7 +199,7 @@ class PostImportPreviewer
   def fetch_metadata url
     return { data: { }, warnings: { 'url' => ['URL が空です．'] } } if url.blank?
 
-    data = PostMetadataFetcher.fetch(url).stringify_keys.compact
+    data = sanitise_metadata(PostMetadataFetcher.fetch(url).stringify_keys.compact)
     warnings = { }
     add_field_warning!(warnings, 'title', TITLE_FETCH_WARNING) if data['title'].blank?
     if data['thumbnail_base'].blank?
@@ -215,6 +215,40 @@ class PostImportPreviewer
     { data: { }, warnings: { 'url' => [METADATA_FETCH_WARNING] } }
   end
 
+  def sanitise_metadata metadata
+    {
+        'title' => sanitise_metadata_title(metadata['title']),
+        'thumbnail_base' => sanitise_metadata_url(metadata['thumbnail_base']),
+        'original_created_from' => sanitise_metadata_time(metadata['original_created_from']),
+        'original_created_before' => sanitise_metadata_time(metadata['original_created_before']),
+        'duration' => sanitise_metadata_duration(metadata['duration']),
+        'tags' => metadata['tags'].to_s.presence }.compact
+  end
+
+  def sanitise_metadata_title value
+    value.is_a?(String) ? value.presence : nil
+  end
+
+  def sanitise_metadata_url value
+    return nil unless value.is_a?(String)
+
+    PostUrlNormaliser.normalise(value)
+  end
+
+  def sanitise_metadata_time value
+    return nil unless value.is_a?(String)
+
+    Time.zone.parse(value)&.iso8601
+  rescue ArgumentError, TypeError
+    nil
+  end
+
+  def sanitise_metadata_duration value
+    return nil unless value.is_a?(Numeric)
+
+    value.positive? ? value.to_i : nil
+  end
+
   def preload_metadata! prepared_rows, fetch_metadata, metadata_cache, existing_posts, url_counts
     urls = prepared_rows.filter_map { |row|
       next unless row[:normal_url].present?