Subscribe only to updates

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@JatinDevDG Thank you. With custom updatedAt timestamps it’s working. Unfortunately, this is very error-prone as every client always need to make sure to update that timestamp. If I forget to update the field in some written client-code, I’ll not receive the data I need.

Do you happen to know when server-side managed createdAt and updatedAt timestamps will be available or what the progress is on this? It would really help in a lot of cases and feels like a very basic feature to have. See also: Query sever timestamps in GraphQL?

Edit: I removed the “solution” tag as this workaround is not really what I’m thinking of.

When implementing this using updatedAt timestamps (set from client or server-side - doesn’t matter) you have to restart the subscription every-time you get data and change the startTime variable accordingly (see query below). Otherwise you’ll run into the same issue - over-fetching large amount of data that you don’t need.

subscription FooUpdates($startTime: DateTime!) {
   queryFoo(filter: {updatedAt: {ge: $startTime} }) {
    ...
   }
}

I suspect that restarting the websocket-connection (potentially multiple times per second) is not very nice to the server.

So instead I propose following directive:

type Foo {
  value: Int!
  bars: [Bar!]!
}

type Bar {
   name: String!
}

subscription FooUpdates {
   queryFoo @subscribeChangesOnly {
     value
     bars {
        name
     }
   }
}

When using this directive, only changes (starting from subscription start) are delivered to the client. Also, changes in sub-graphs will only return the changed part of the graph.

Examples

  • 100 Foos in the database, one of them will get its value changed: → Client will receive only that item.
  • 100 Foos in the database, one Bar get its name changed: → Client will receive only that foo which corresponds to the changed Bar object. Also, only the changed bar object will be returned and not all bar-childs of foo.

@JatinDevDG Please reconsider adding this feature!