[capink]

EDIT: A modified version of this action is available as a builtin action in the action chains plugin starting from version 1.4.0. The builtin action is called "Search Using Templates".

This is a custom action that allows constructing a calibre search using calibre template editor. The search can be a simple text search or a search constructed from a template.

# python3 compatibility
from six import text_type as unicode

from calibre import prints
from calibre.constants import DEBUG
from calibre.gui2 import error_dialog
from calibre.ebooks.metadata.book.formatter import SafeFormat

from calibre_plugins.action_chains.actions.base import ChainAction
from calibre_plugins.action_chains.database import is_search_valid
from calibre_plugins.action_chains.templates import check_template, get_metadata_object
from calibre_plugins.action_chains.templates.dialogs import TemplateBox

try:
    load_translations()
except NameError:
    prints("ActionsChain::action/search.py - exception when loading translations")

class TemplateSearchWidget(TemplateBox):
    def __init__(self, parent, plugin_action, action, name, title):
        self.plugin_action = plugin_action
        self.action = action
        self.gui = plugin_action.gui
        self.db = self.gui.current_db
        mi = get_metadata_object(self.gui)
        TemplateBox.__init__(
                self,
                parent,
                plugin_action,
                template_text='',
                placeholder_text=_('Enter a search expression here. It can be either '
                                   'an ordinary text string or a template.'),
                mi=mi
            )
        self.setWindowTitle(title)

    def textbox_changed(self):
        TemplateBox.textbox_changed(self)
        template = self.template_value.text()
        text = SafeFormat().safe_format(template, self.mi, 'Exception: ', self.mi, template_functions=self.plugin_action.template_functions)
        if text:
            ok = is_search_valid(self.db, text) and not text.lower().startswith('exception:')
            ss = 'QLineEdit { border: 2px solid %s; border-radius: 3px }' % (
            '#50c878' if ok else '#FF2400')
            self.template_value.setStyleSheet(ss)
        else:
            self.template_value.setStyleSheet('')

    def load_settings(self, settings):
        if settings:
            template = settings['template']
            self.textbox.insertPlainText(template)

    def save_settings(self):
        settings = {}
        settings['template'] = unicode(self.textbox.toPlainText()).rstrip()
        return settings

    def accept(self):
        self.settings = self.save_settings()
        # validate settings
        is_valid = self.action.validate(self.settings)
        if is_valid is not True:
            msg, details = is_valid
            error_dialog(
                self,
                msg,
                details,
                show=True
            )
            return
        TemplateBox.accept(self)

class TemplateSearchAction(ChainAction):

    name = 'Template Search'

    def run(self, gui, settings, chain):
        template = settings['template']
        template_output = chain.evaluate_template(template, book_id=None)
        gui.search.clear()
        gui.search.set_search_string(template_output)

    def validate(self, settings):
        gui = self.plugin_action.gui
        db = gui.current_db
        if not settings:
            return (_('Settings Error'), _('You must configure this action before running it'))
        mi = get_metadata_object(gui)
        is_template_valid = check_template(settings['template'], self.plugin_action, print_error=False)
        if is_template_valid is not True:
            return is_template_valid
        search_text = SafeFormat().safe_format(settings['template'], mi, 'Exception: ', mi, template_functions=self.plugin_action.template_functions)
        if not is_search_valid(db, search_text):
            return (_('Settings Error'), _('Search ({}) is not valid'.format(search_text)))
        return True

    def config_widget(self):
        return TemplateSearchWidget

N.B This custom action will not work with Action Chains versions < 1.2.0