Add a property to Book to fix #1181

openlp/plugins/songs/lib/db.py

@@ -103,6 +103,13 @@ class Book(BaseModel):
     """
     Book model
     """
+    @property
+    def songs(self):
+        """
+        A property to return the songs associated with this book.
+        """
+        return [sbe.song for sbe in self.entries]
+
     def __repr__(self):
         return '<Book id="{myid:d}" name="{name}" publisher="{publisher}" />'.format(myid=self.id,
                                                                                      name=self.name,
@@ -383,7 +390,7 @@ def init_schema(url):
         class_mapper(SongBookEntry)
     except UnmappedClassError:
         mapper(SongBookEntry, songs_songbooks_table, properties={
-            'songbook': relation(Book)
+            'songbook': relation(Book, backref='entries')
         })
     try:
         class_mapper(Book)

tests/openlp_plugins/songs/forms/test_songmaintenanceform.py

@@ -24,7 +24,7 @@ Package to test the openlp.plugins.songs.forms.songmaintenanceform package.
 import pytest
 import os
 
-from unittest.mock import MagicMock, call, patch, ANY
+from unittest.mock import MagicMock, call, create_autospec, patch, ANY
 
 from PyQt5 import QtCore, QtWidgets
 
@@ -208,10 +208,43 @@ def test_delete_item(mocked_critical_error_message_box, form_env):
     mocked_get_current_item_id.assert_called_once_with(mocked_list_widget)
     mocked_manager.get_object.assert_called_once_with(mocked_item_class, 1)
     mocked_critical_error_message_box.assert_called_once_with(dialog_title, delete_text, form, True)
-    mocked_manager.delete_object(mocked_item_class, 1)
+    mocked_manager.delete_object.assert_called_once_with(mocked_item_class, 1)
     mocked_reset_func.assert_called_once_with()
 
 
+@patch('openlp.plugins.songs.forms.songmaintenanceform.critical_error_message_box')
+def test_delete_book_assigned(mocked_critical_error_message_box, form_env):
+    """
+    Test the _delete_item() method
+    """
+    # GIVEN: Some mocked items
+    form = form_env[0]
+    mocked_manager = form_env[1]
+    mocked_item = create_autospec(Book, spec_set=True)
+    mocked_item.id = 1
+    mocked_manager.get_object.return_value = mocked_item
+    mocked_critical_error_message_box.return_value = QtWidgets.QMessageBox.Yes
+    mocked_item_class = MagicMock()
+    mocked_list_widget = MagicMock()
+    mocked_reset_func = MagicMock()
+    dialog_title = 'Delete Book'
+    delete_text = 'Are you sure you want to delete the selected book?'
+    error_text = 'This book cannot be deleted, it is currenty assigned to at least one song.'
+
+    # WHEN: _delete_item() is called
+    with patch.object(form, '_get_current_item_id') as mocked_get_current_item_id:
+        mocked_get_current_item_id.return_value = 1
+        form._delete_item(mocked_item_class, mocked_list_widget, mocked_reset_func, dialog_title, delete_text,
+                          error_text)
+
+    # THEN: The right things should have been called
+    mocked_get_current_item_id.assert_called_once_with(mocked_list_widget)
+    mocked_manager.get_object.assert_called_once_with(mocked_item_class, 1)
+    mocked_critical_error_message_box.assert_called_once_with(dialog_title, error_text)
+    mocked_manager.delete_object.assert_not_called()
+    mocked_reset_func.assert_not_called()
+
+
 @patch('openlp.plugins.songs.forms.songmaintenanceform.QtWidgets.QListWidgetItem')
 @patch('openlp.plugins.songs.forms.songmaintenanceform.Author')
 def test_reset_authors(MockedAuthor, MockedQListWidgetItem, form_env):