GoNES | Go study , building a NES emulator

Destruct props, So you can change your component to this:

The reason you need to apply .result is to do with the difference between queries (Query type) and actions (DBIO) in Slick.

By itself, the lists.filter line is a query. However, the third line (the update) is an action. If you left the .result off your for comprehension would have a type mismatch between a Query and a DBIO (action).

Because you're going to db.run the result of the for comprehension, the for comprehension needs to result in an DBIO action, rather than a query. In other words, putting a .result there is the right thing to do because you're constructing an action to run in the database (namely, fetching some data for the user).

You'll then going to run another action later to update the database. So in all, you're using for to combine two actions (two runnable SQL expressions) into a single DBIO. That's the x you yield, which is executed by db.run.

This is working for you, and that's just fine.

There's a small amount of duplication. You might spot your query on the first line, is very similar to the update query. You could abstract that out into a value:

The service is returning a different feature id for the same feature at each call, so the bbox strategy won't work correctly and the features are being repeated

It looks like the OBJ_ID property uniquely identifies features so you would need a custom loader to set the feature id to OBJ_ID, e.g.