Amplify GraphQL order points by lat-long

Question

I have a graphql query that returns a list of pullup bar objects.

Query:

query PullUpBarsByDate($userID: String) {
  PullUpBarsByDate(
    type: "PullUpBar"
    sortDirection: DESC
  ) {
    items {
      id
      lat
      lng
      userID
    }
  }
}

Returns something like this:

[
  {
    id: "rf6zrd1prm",
    lat: 63.50235889533083,
    lng: 28.426290788320724,
  },
  {
    id: "y80ymnlgzi7",
    lat: 62.5654380797649,
    lng: 17.338090077030582,
  },
  {
    id: "ufpgut6wwh",
    lat: 56.85363369278235,
    lng: 30.675813028973685,
  },
  {
    id: "p80r9j2li8a",
    lat: 55.274815489484716,
    lng: 24.094777714658456,
  },
  {
    id: "ydnlsd1vn8c",
    lat: 50.61633534684824,
    lng: 26.500618762197323,
  }
]

I’m wondering if it’s possible to order the returned list of items based on how far this would be from my location, given that my location is known on the application side. Something like this formula would be perfect: d=√((x2 – x1)² + (y2 – y1)²)

score 2 · Accepted Answer · 2023-11-19 18:46:16Z

GraphQL does not include native filtering/sorting capabilities.

This should be done in the resolver for the PullUpBarsByDate query, i.e. in the back end. If your data is coming from a database with geo capabilities (ex postgres/PostGIS) then you could do the sorting directly in the database query. Otherwise you could sort in the resolver code itself.

Note that given the range of lat-long data you have a flat earth model will not give you very accurate distances.

Thanks, well I'm using AWS Amplify API so not sure if it supports postgress/postgis, but will try to find out. And yeah I didn't think about long-lat distances, but does it matter for ordering? The distance will be inaccurate but I only care about relative distance for ordering purposes — 12 hours ago
You will have cases where the order of distances will be off as well as the absolute value since the errors will be heading dependent. — 2 hours ago
Amplify can do geo queries. This post might help: gerard-sans.medium.com/… — 38 mins ago

Amplify GraphQL order points by lat-long