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geo_db_meta = MetaData()
geo_db_meta.reflect(bind=engine)

geom_table = geo_db_meta.tables[table_name]
initial_cols = _column_metadata_from_columns(geom_table.columns)
stmt = (
    update(snapshots).where(snapshots.c.id==snapshot_id)
    .values(columns=initial_cols)
)
session = orm.Session(bind=bind)

rayrayzayzay

type Dog = {
  numberOfLegs: number
  collar: {
    name: string
    material: "leather" | "plastic"
  }
}

type Cat = {
  numberOfLegs: number

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function getName(pet: Pet): string {
  if ("collar" in pet) {
    // TypeScript knows that pet is a Dog now
    return pet.collar.name
  }

  // TypeScript knows that it can only be a Cat now
  return pet.microchip.name
}

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function isCat(pet: Pet): pet is Cat {
  return "microchip" in pet
}

function isDog(pet: Pet): pet is Dog {
  return "collar" in pet
}

function getName(pet: Pet): string {
  if (isDog(pet)) return pet.collar.name

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function isCat(pet: Pet): pet is Cat {
  return "mcirochip" in pet // 🔥 spelling mistake - no cats ever!
}

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type Hamster = {
  microchip: {
    id: string
    name: string
  }
}

type Pet = Dog | Cat | Hamster

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type Dog = {
  kind: "dog" // 👀
  numberOfLegs: number
  collar: {
    name: string
    material: "leather" | "plastic"
  }
}

type Cat = {

rayrayzayzay

❌ Unclear relationships between properties

type UserProfileRequest = {
  isLoading: boolean
  data?: UserProfileData
  errorMessage?: string
  statusCode?: number
}

// NOTE: In reality, we would probably use a generic like Loadable<UserProfileData>

rayrayzayzay

❌ A "simple" component which isn't really simple

function UserProfile({request}: {request: MyProfileRequest}) {

  // can we have stale data while we're loading? I guess not?
  if (request.isLoading) return <Spinner />

  // this goes before checking the errors, so I presume we can't have
  // data and an error together? Or maybe we just don't care if there's
  // an error but we get data?

rayrayzayzay

✅ Explicit modeling of distinct states

type UserProfileFetching = {
  status: "fetching"
}

type UserProfileSuccess = {
  status: "success"
  data: UserProfileData
  statusCode: number