Correct new card ordering, clean due number

Rationale

This add-on solve a problem related to the order of new card. This problem only appear either:

• if you download a shared deck with this problem (you have no way to know whether it is the case while downloading)
• if you edited a note, and created new cards of this note, when some cards where already reviewed before version 2.1.16 of Anki.

More precisely, anki is supposed to show you all new cards of a note before showing you cards of another note. There are exceptions to this rules. For example, when you see a card, you may bury its siblings. In which case the card which should have been shown today is not shown and another card must be selected. But the main idea is that, if a note have a few cards, you'll discover all of those cards near in the same week, or at worst in the same month.

However, it may occurs that suddenly, anki decides to show you the first card of each note before showing you the second card of any note. Depending on how you use anki, it may be a real problem, and there is virtually no way to correct it by yourself. This is why this add-on is here.

You can see whether you need this add-on by opening a browser, and searching "due>=1000000". If you see any card it means that this add-on may help you. Otherwise, this add-on won't hurt, and won't change anything.

Usage

In the main window, select "Tools>clean due". And that's it.

Warning

I can't imagine how this add-on could break anything. I hope this means warning is useless. However, better be safe, and be sure to make a back up before trying the add-on.

Internal

This add-on does not change any method.

Here is the explanation of the cause of the bug, and of the solution.

When selecting a new card in a deck d, anki selects the card in d, which is new, not suspended, not buried, and whose due value is minimal. This mean that the only purpose of the due value of new card is to decide in which order new cards will be shown. Intuitively, the due value is a computation, done in advance, to find new cards quickly. Which means that if this computation had an error, new cards will be found in the wrong order.

The due value of a new note is chosen to be the greatest due value of the collection, plus one. Which means that the due given to cards always increase. However, for technical reason, the due is capped at 1,000,000 (this ensures that the due value holds on 32 bits, i.e. on an int). It is usually not a problem since most collection does not have a million note. However, if for some reason you have any card whose due value is 1,000,000, all cards will then have this due value. And suddenly due does not means anything anymore.

Thus, this add-on recompute the due value of ALL new cards. Hence, if you have n new cards, the due values will be from 0 to n. It will then randomize the order of new cards when the card is in a deck whose option requires it.

Possible cause of the problem

The trouble being that, if you change a deck's option, and choose to see new cards in random order/order of creation, then anki will give a new due value to each card in decks having this deck option.

The bug mentionned above is caused by the fact that the due number of each card is always incremented and never decremented. However

The problem may also occur if, in the browser, you select Cards>Reposition and choose a value at least equal to 1,000,000.

Version 2.0

Port by lovac42

Links, licence and credits