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Comment by wawhal | Hacker News Reader

It works with circular references. For example, this works:

  {
    "user": [
          { "id": 456, "name": "Sita K", "user_id": 123 },
          { "id": 123, "name": "John Doe", "user_id": 123  }
    ]
  }

Do you have anything else in mind?

PS: Co-author here

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But then to go from user 456 to user 123 via the field user_id do I have to do a linear search of all users to check their IDs?

No. The tool also creates relationships based on foreign key references using Hasura. So to query all the users with the child users, you would make a GraphQL query like:

  query {
    user {
      id
      name
      childUser: userByUserId {
        id
        name
      }
    }
  }

The response would be:

  {
    "data": {
      "user": [
        {
          "id": 123,
          "name": "John Doe",
          "childUser": {
            "id": 123,
            "name": "John Doe"
          }
        },
        {
          "id": 456,
          "name": "Sita K",
          "childUser": {
            "id": 123,
            "name": "John Doe"
          }
        }
      ]
    }
  }

Did I answer your question?

Those child users don't then have their own child users (because it's cyclic) so do you have to choose one option of the two, both with a drawback?

I was thinking you could replace or supplement the real user IDs with their indices in the array of returned users.

I am sorry, but if possible, could you elaborate @chrisseaton? (preferably with a bit more punctuation :D)

With more punctuation? What's that supposed to mean? I've written two short sentences. It's not some wall of text.

So, is a hypothetical scenario, an employee that is their own supervisor?

Yes, but I'm not sure if you're implying that it's a nonsensical situation with that example. Lots of real-world graphs have genuine cycles.

For a good example of unexpected cycles you can see this classic question on genealogy software:

https://stackoverflow.com/questions/6163683/cycles-in-family...

... wouldn't the second line have to be "user_id": 456, in order to really be circular?

Circular references basically mean that a table is referencing itself. Any row in the table could reference any row.

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