Updating an @Selection member

[seanmrich]

Using the column groups idea, I have a timestamps type

@Selection
struct Timestamps {
  var created: Date
  var deleted: Date?
}

I use this to simplify my tables

@Table
struct Item {
  ...
  var timestamps: Timestamps
}

This works fine for fetching Items, but now let's say I want to soft delete one:

try Item
  .find(id)
  .update {
    $0.timestamps.deleted = Date()
//  ^ 🛑 Getter for 'subscript(dynamicMember:)' is unavailable
  }

At first I thought this meant you just can't assign through a property using @Selection, but then I found that this works:

try Item
  .find(id)
  .update {
    $0.timestamps.deleted = #sql("\(Date())")
  }

I'll be honest, I don't get why this is the case. I went spelunking in the code but came up empty. For times when I do this a bunch I could add an extension like this:

extension Updates<Item> {
  mutating func delete(at date: Date) {
    self.timestamps.deleted = #sql("\(date)")
  }
}
// Now you can do this
try Item
  .find(id)
  .update {
    $0.delete(at: Date())
  }

It's not a terrific solution though since you have to do this for each nested property you want to update. Is there a better approach to modifying @Selection members?

[stephencelis]

This is mainly due to a mismatch between Date and Optional<Date>. Both of the following disambiguate things:

// Use `#bind` macro to give the query language a hint.
$0.timestamps.deleted = #bind(Date())

// Make optionality explicit:
$0.timestamps.deleted = Optional(Date())

We can explore making this nicer, though. Thanks for the example!

[seanmrich]

Ah, that makes sense. Still feeling my way around in this library, but this will help a ton. Thank you!