Fix computation of Model req field

Also remove user ability to control which Cards a Note has. Anki doesn't actually support this; it enforces that the set of Cards a Note has is based on which Fields it has.
kerrickstaley · Feb 19, 2017 · b7a5821 · b7a5821
1 parent ccb3b77
commit b7a5821
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Showing 4 changed files with 96 additions and 37 deletions.
diff --git a/README.md b/README.md
@@ -86,17 +86,6 @@ class MyNote(genanki.Note):
     return genanki.guid_for(self.fields[0], self.fields[1])
 ```
 
-## Only Including Certain Cards
-By default, all `Card`s are included when you add a `Note` to a deck. You can control which cards are included by
-explicitly passing `cards=[]` to `Note()` and then calling `add_card` with the card number:
-
-```python
-my_note = Note(
-  ...,
-  cards=[])
-my_note.add_card(1)  # add the card corresponding to the 2nd template
-```
-
 ## sort_field
 Anki has a value for each `Note` called the `sort_field`. Anki uses this value to sort the cards in the Browse
 interface. Anki also is happier if you avoid having two notes with the same `sort_field`, although this isn't strictly

diff --git a/genanki/__init__.py b/genanki/__init__.py
@@ -1,7 +1,9 @@
+from cached_property import cached_property
+from copy import copy
 import json
 import hashlib
 import os
-import random
+import pystache
 import sqlite3
 import tempfile
 import time
@@ -60,6 +62,44 @@ def set_templates(self, templates):
     elif isinstance(templates, str):
       self.templates = yaml.load(templates)
 
+  @cached_property
+  def _req(self):
+    """
+    List of required fields for each template. Format is [tmpl_idx, "all", [req_field_1, req_field_2, ...]].
+
+    Partial reimplementation of req computing logic from Anki. We only support "all" style req, not "any".
+
+    The goal is to figure out which fields are "required", i.e. if they are missing then the front side of the note
+    doesn't contain any meaningful content.
+    """
+    sentinel = 'SeNtInEl'
+
+    field_names = [field['name'] for field in self.fields]
+    field_values = {field: sentinel for field in field_names}
+
+    req = []
+    for template_ord, template in enumerate(self.templates):
+      required_fields = []
+      for field_ord, field in enumerate(field_names):
+        fvcopy = copy(field_values)
+        fvcopy[field] = ''
+
+        rendered = pystache.render(template['qfmt'], fvcopy)
+
+        if sentinel not in rendered:
+          # when this field is missing, there is no meaningful content (no field values) in the question, so this field
+          # is required
+          required_fields.append(field_ord)
+
+      if not required_fields:
+        raise Exception(
+          'Could not compute required fields for this template; please check the formatting of "qfmt": {}'.format(
+            template))
+
+      req.append([template_ord, 'all', required_fields])
+
+    return req
+
   def to_json(self, now_ts, deck_id):
     for ord_, tmpl in enumerate(self.templates):
       tmpl['ord'] = ord_
@@ -75,10 +115,6 @@ def to_json(self, now_ts, deck_id):
       field.setdefault('size', 20)
       field.setdefault('sticky', False)
 
-    # TODO: figure out how req works
-    all_field_ords = list(range(len(self.fields)))
-    req = [[tmpl_ord, "all", all_field_ords] for tmpl_ord in range(len(self.templates))]
-
     return {
       "css": self.css,
       "did": deck_id,
@@ -89,7 +125,7 @@ def to_json(self, now_ts, deck_id):
                   "\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
       "mod": now_ts,
       "name": self.name,
-      "req": req,
+      "req": self._req,
       "sortf": 0,
       "tags": [],
       "tmpls": self.templates,
@@ -101,13 +137,13 @@ def to_json(self, now_ts, deck_id):
 
 class Card:
   def __init__(self, ord_):
-    self.ord_ = ord_
+    self.ord = ord_
 
   def write_to_db(self, cursor, now_ts, deck_id, note_id):
     cursor.execute('INSERT INTO cards VALUES(null,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?);', (
         note_id,    # nid
         deck_id,    # did
-        self.ord_,  # ord
+        self.ord,   # ord
         now_ts,     # mod
         -1,         # usn
         0,          # type (=0 for non-Cloze)
@@ -131,15 +167,8 @@ def __init__(self, model=None, fields=None, sort_field=None, tags=None, cards=No
     self.fields = fields
     self.sort_field = sort_field
     self.tags = tags or []
-    self.cards = cards
     self.guid = guid
 
-  def add_card(self, *args, **kwargs):
-    if len(args) == 1 and not kwargs and isinstance(args[0], Card):
-      self.cards.append(args[0])
-    else:
-      self.cards.append(Card(*args, **kwargs))
-
   @property
   def sort_field(self):
     return self._sort_field or self.fields[0]
@@ -148,15 +177,15 @@ def sort_field(self):
   def sort_field(self, val):
     self._sort_field = val
 
-  @property
+  # We use cached_property instead of initializing in the constructor so that the user can set the model after calling
+  # __init__ and it'll still work.
+  @cached_property
   def cards(self):
-    if self._cards is None:
-      return [Card(i) for i in range(len(self.model.templates))]
-    return self._cards
-
-  @cards.setter
-  def cards(self, val):
-    self._cards = val
+    rv = []
+    for card_ord, _, required_field_ords in self.model._req:
+      if all(self.fields[ord_] for ord_ in required_field_ords):
+        rv.append(Card(card_ord))
+    return rv
 
   @property
   def guid(self):

diff --git a/setup.py b/setup.py
@@ -10,6 +10,9 @@
       packages=['genanki'],
       zip_safe=False,
       install_requires=[
+        'cached-property',
+        'frozendict',
+        'pystache',
         'pyyaml',
       ],
       keywords=[

diff --git a/tests/test_genanki.py b/tests/test_genanki.py
@@ -29,6 +29,27 @@
   ],
 )
 
+TEST_CN_MODEL = genanki.Model(
+  345678, 'Chinese',
+  fields=[{'name': 'Traditional'}, {'name': 'Simplified'}, {'name': 'English'}],
+  templates=[
+    {
+      'name': 'Traditional',
+      'qfmt': '{{Traditional}}',
+      'afmt': '{{FrontSide}}'
+              '<hr id="answer">'
+              '{{English}}',
+    },
+    {
+      'name': 'Simplified',
+      'qfmt': '{{Simplified}}',
+      'afmt': '{{FrontSide}}'
+              '<hr id="answer">'
+              '{{English}}',
+    },
+  ],
+)
+
 
 class TestWithCollection:
   def setup(self):
@@ -41,7 +62,6 @@ def setup(self):
   def test_generated_deck_can_be_imported(self):
     deck = genanki.Deck(123456, 'foodeck')
     note = genanki.Note(TEST_MODEL, ['a', 'b'])
-    note.add_card(0)
     deck.add_note(note)
 
     outf = tempfile.NamedTemporaryFile(suffix='.apkg', delete=False)
@@ -58,11 +78,10 @@ def test_generated_deck_can_be_imported(self):
 
     assert imported_deck['name'] == 'foodeck'
 
-  def test_card_isEmtpy__with_2_fields__succeeds(self):
+  def test_card_isEmpty__with_2_fields__succeeds(self):
     """Tests for a bug in an early version of genanki where notes with <4 fields were not supported."""
     deck = genanki.Deck(123456, 'foodeck')
     note = genanki.Note(TEST_MODEL, ['a', 'b'])
-    note.add_card(0)
     deck.add_note(note)
 
     outf = tempfile.NamedTemporaryFile(suffix='.apkg', delete=False)
@@ -78,3 +97,22 @@ def test_card_isEmtpy__with_2_fields__succeeds(self):
 
     # test passes if this doesn't raise an exception
     anki_card.isEmpty()
+
+  def test_Model_req(self):
+    assert TEST_MODEL._req == [[0, 'all', [0]]]
+
+  def test_Model_req__cn(self):
+    assert TEST_CN_MODEL._req == [[0, 'all', [0]], [1, 'all', [1]]]
+
+  def test_notes_generate_cards_based_on_req(self):
+    # has 'Simplified' field, will generate a 'Simplified' card
+    n1 = genanki.Note(model=TEST_CN_MODEL, fields=['中國', '中国', 'China'])
+    # no 'Simplified' field, so it won't generate a 'Simplified' card
+    n2 = genanki.Note(model=TEST_CN_MODEL, fields=['你好', '', 'hello'])
+
+    assert len(n1.cards) == 2
+    assert n1.cards[0].ord == 0
+    assert n1.cards[1].ord == 1
+
+    assert len(n2.cards) == 1
+    assert n2.cards[0].ord == 0