Re: Design for storing likes/dislikes?

Hi,

Hmm, I'm thinking I might need to go for an enum/choices rather than a NullBooleanField.

There are actually four states (so far) that can exist in the relationship between a user and a widget.

1. Like
2. Unlike
3. No vote (i.e. abstain).
4. Not asked yet

I suppose I could still use NullBooleanField, but use Like=True, Unlike=False, No Vote = Null, and have that row not exist in the M2M if we haven't asked about that widget yet - however, not sure if that's a bit ambiguous? And it may close the door down the track to other states?

Also, it definitely is a M2M between Users and Widgets - since each user can like/unlike many widgets, and each widget can be liked/unliked by many users.

Cheers,

Victor

On Saturday, 20 July 2013 00:57:54 UTC+10, Steven Smith wrote:

I've used NullBooleanField for this before, as well.  A lot quicker to query on than a ManyToMany, also.



On Tuesday, July 16, 2013 9:24:54 PM UTC-4, donarb wrote:

On Tuesday, July 16, 2013 5:29:47 PM UTC-7, Victor Hooi wrote:

Hi,

We have a list of users, who are going to like/dislike various widgets.

My question is regarding how to store the like/dislikes.

Essentially, there can be three states between a user and a widget - like, dislike, and unrated, so it's not just a straight Boolean.

I'm thinking of just doing a M2M between user and widgets models, and then storing an extra field on that M2M.

I can either store a Boolean, for whether the item is liked/unliked - and then an unrated item simply won't be exist in the table.

Or I can store a integer (with a choice tupled defined), with say 0=unrated, 1=like, 2 = unlike, and all possible combinations are listed.

We'll be doing queries to compare users, and see if their likes/dislikes intersect.

Are there any pros/cons of the two approaches for this given query, or is there perhaps a more efficient way of storing this data?

Cheers,

Victor

Django has a NullBooleanField that allows 3 states, Unknown (null), True, False.

 

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