Add vocabulary model and migrations

[bethanyaconnor]

Adds the model and migrations for the vocabulary model.

I decided to add a key as the spec calls out a likelihood that some courses will have multiple definitions per word (in the case of Common Sense). For now, my plan was to make the key equal to the word.

This PR adds the vocabulary/course version association but the lesson/vocabulary association will come in a later PR in order to limit the number of migrations per PR.

Links

• spec
• jira

Testing story

Reviewer Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[davidsbailey]

in order to create more than one of these, I think we will want this to be a sequence, e.g.

code-dot-org/dashboard/test/factories/factories.rb

Line 806 in 4650698

sequence(:key) {|n| "objective-#{n}"}

also, just confirming my understanding that this will be an opaque id generated with something like SecureRandom.uuid, is that correct?

[bethanyaconnor]

I was originally thinking that key would be the word to start with but I think what you said makes more sense. We'll still need to prevent curriculum writers adding multiple definitions for the same word for now but I think that can be done in other ways. I'll add this sequence to the factory.

[davidsbailey]

should we consider just getting rid of the key column and having word be the key? sorry to add more options here.

[bethanyaconnor]

Don't be sorry -- I've been going back and forth between a bunch of these options! I thought about that but it's likely we will want to have multiple definitions for a handful of words. I thought about adding the key then but then we'd have to backfill everything already in the database.

[bethanyaconnor]

Just to summarize what we talked about offline -- we know we will need to have multiple definitions per word at some point, though not in the near term. We also need a unique identifier that is human-readable-ish in order to embed them in markdown. So, we will set the key to be the word in the near term and, in the future, generate human-readable alternate keys for duplicate definitions, like we do for resources

[dmcavoy]

Looks good to me