Plugins can be used to automate some of the workflow. For instance ebooklib.plugins.tidyhtml plugins automatically cleans HTML output for you. FootnotePlugin for instance rewrites custom footnotes into EPUB3 kind of footnotes. Without these plugins you would need to do wanted transformations before setting or getting content from your chapters.

There is a ebooklib.plugins.base.BasePlugin class which you need to extend. These are the methods you can override.

Method Arguments Description
before_write book Processing before book save
after_write book Processing after book save
before_read book Processing before book read
after_read book Processing after book read
item_after_read book, item Process general item after read
item_before_write book, item Process general item before write
html_after_read book, chapter Processing HTML before read
html_before_write book, chapter Processing HTML before save

Custom plugin

This is our use case. We have online WYSIWYG editing system for editing content of our books. In the editor to link to our other page we use this syntax <a href=”../page/”>Our page</a> but in the EPUB book we would need to link to page.xhtml file for instance.

We could do the transformations manually or we could write a plugin which does all of the work for us. We override html_before_write method. We parse the content of our chapter, find all links, replace them with new href and finally set new content to the chapter.

    from urlparse import urlparse, urljoin
except ImportError:
    from urllib.parse import urlparse, urljoin

from lxml import  etree

from ebooklib.plugins.base import BasePlugin
from ebooklib.utils import parse_html_string

class MyeLinks(BasePlugin):
    NAME = 'My Links'

    def html_before_write(self, book, chapter):
            tree = parse_html_string(chapter.content)

        root = tree.getroottree()

        if len(root.find('body')) != 0:
            body = tree.find('body')

            for _link in body.xpath('//a'):
                _u = urlparse(_link.get('href', ''))

                # Let us care only for internal links at the moment
                if _u.scheme == '':
                    if _u.path != '':
                        _link.set('href', '%s.xhtml' % _u.path)

                    if _u.fragment != '':
                        _link.set('href', urljoin(_link.get('href'), '#%s' % _u.fragment))

                    if _link.get('name') != None:
                        _link.set('id', _link.get('name'))
                        etree.strip_attributes(_link, 'name')

        chapter.content = etree.tostring(tree, pretty_print=True, encoding='utf-8')

When you want to use it just pass the list of plugins you want to use as extra option to the write_epub method (also to read_epub method). Plugins will be executed in the order they are defined in the list.

epub.write_epub('test.epub', book, {"plugins": [MyLinks()]})