https://github.com/PresKhaled/epubx

[PresKhaled]

This version has been added some simple features to it, as follows: -

• Added [EpubLanguageRelatedAttributes] to certain classes (EpubMetadataDescription, EpubMetadataPublisher, EpubMetadataRight) and will be filled during the processing of some meta items to support the xml:lang, and dir attributes.
  [PackageReader].readMetadata > result.MetaItems are now filled in before iterating over the children of [metadataNode].
• Added support for the specification of ePub 3.0 for the element's creator and contributor.
• Types of titles were collected instead of one title, to be processed in the application that uses the package.
  • To provide processing: Main, subtitle, short, collection, edition and expanded.
    Example of the process:

final epubx.EpubMetadataTitle primaryTitle = (titles.firstWhereOrNull(
      (epubx.EpubMetadataTitle? titleElement) {
        final epubx.EpubMetadataMeta? associatedMeta = _getMetaAssociatedWithTitle(
          metaItems: epubMetadata.MetaItems,
          titleElement: titleElement,
        );

        if (associatedMeta != null && associatedMeta.Scheme == null) {
          return (associatedMeta.Content == 'main');
        }

        return false;
      },
    ) ??
    titles.first);

final epubx.EpubMetadataTitle? subtitle = titles.firstWhereOrNull(
      (epubx.EpubMetadataTitle? titleElement) {
        final epubx.EpubMetadataMeta? associatedMeta = _getMetaAssociatedWithTitle(
          metaItems: epubMetadata.MetaItems,
          titleElement: titleElement,
        );

        if (associatedMeta != null && associatedMeta.Scheme == null) {
          return (associatedMeta.Content == 'subtitle');
        }

        return false;
      },
    );

static epubx.EpubMetadataMeta? _getMetaAssociatedWithTitle({
    required List<epubx.EpubMetadataMeta>? metaItems,
    required epubx.EpubMetadataTitle? titleElement,
  }) {
    return metaItems?.firstWhereOrNull(
      (meta) => (meta.Refines == '#${titleElement?.Id}' && (meta.Property == 'title-type')),
    );
  }

The data coming from the package can be transferred to classes and stored as it is in a database that accepts this matter.
I do not like to use Pull Requests permanently.