Event Sourcing Adventures

17 Oct 2020 - tom

event-sourcing-adventures

Primary goal:

setup the culture blog’s data based solely on an event collection in Firebase

step 1

create events collection in firestore

step 2

consider what kind of events will be needed:

• publish: when a user publishes a piece
• view: when a user views a piece … probably many more, but just these two are fine for now.

question: every event will need an event type… I guess i would do this by creating a base event type and then all events extend that type.. hmm another case for typesciprt

– note: I should really introduce typescript so i can type these events so they always have the same shape

publish

needs to contain all piece information:

• event_type
• reference/link (content)
• why (250 words max)
• who (author)
• created_at
• category
• emotional_tag ??? (in development)
• title (maybe)

view:

• piece_id
• user_uid

step 3

send respective events on create and view

3.1 publish

publish event is trivial, just upate the create function

3.2 view

less trivial because showing a random piece does not work yet. So first step, make random page work with publish events.

plan of attack:

1. get all publish events
2. get all view events of current user
3. filter publish events with piece ids

another trouble: how to get a “piece_id” if i am creating an event, not a piece..? for now i can use the event_id as the id of hte piece because publish event = piece right now… but in the future this should be resolved.

… almost there, current problem is the queries returnd from firebase are objects, not arrays.

… so it works now, but there is what I would consider some not so good hacking to turn the firebase query response into an array

I think that is all we have time for now! Taaa taaa! This has been a great exercise!