MongoServerError: Can't extract geo keys, unknown GeoJSON type: {} when using a point field inside an array with mixed empty and filled values

[jhb-dev]

Describe the Bug

When defining a collection with a point field inside an array, a MongoServerError occurs during document saving. This error only appears when the array contains at least one filled point field and one empty point field. The error does not occur if all point fields are either empty or all are filled.

It appears the issue arises when attempting to save an empty point field ({}), as MongoDB cannot properly interpret it as a valid GeoJSON type. The error message is as follows:

ERROR: Can't extract geo keys: { _id: ObjectId('679900885b83e7325fbd11ed'), locations: [ { location: { type: "Point", coordinates: [ 1, 1 ] }, id: "6799007c6bf35e2d5563d600" }, { location: {}, id: "6799007e6bf35e2d5563d602" } ], createdAt: new Date(1738080392536), updatedAt: new Date(1738080392536), __v: 0 }  unknown GeoJSON type: {}
    err: {
      "type": "MongoServerError",
      "message": "Can't extract geo keys: { _id: ObjectId('679900885b83e7325fbd11ed'), locations: [ { location: { type: \"Point\", coordinates: [ 1, 1 ] }, id: \"6799007c6bf35e2d5563d600\" }, { location: {}, id: \"6799007e6bf35e2d5563d602\" } ], createdAt: new Date(1738080392536), updatedAt: new Date(1738080392536), __v: 0 }  unknown GeoJSON type: {}",
      "stack":
          MongoServerError: Can't extract geo keys: { _id: ObjectId('679900885b83e7325fbd11ed'), locations: [ { location: { type: "Point", coordinates: [ 1, 1 ] }, id: "6799007c6bf35e2d5563d600" }, { location: {}, id: "6799007e6bf35e2d5563d602" } ], createdAt: new Date(1738080392536), updatedAt: new Date(1738080392536), __v: 0 }  unknown GeoJSON type: {}
              at InsertOneOperation.execute (webpack-internal:///(rsc)/./node_modules/.pnpm/[email protected]_@[email protected]/node_modules/mongodb/lib/operations/insert.js:51:19)
              at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
              at async tryOperation (webpack-internal:///(rsc)/./node_modules/.pnpm/[email protected]_@[email protected]/node_modules/mongodb/lib/operations/execute_operation.js:203:20)
              at async executeOperation (webpack-internal:///(rsc)/./node_modules/.pnpm/[email protected]_@[email protected]/node_modules/mongodb/lib/operations/execute_operation.js:73:16)
              at async Collection.insertOne (webpack-internal:///(rsc)/./node_modules/.pnpm/[email protected]_@[email protected]/node_modules/mongodb/lib/collection.js:157:16)
      "errorResponse": {
        "index": 0,
        "code": 16755,
        "errmsg": "Can't extract geo keys: { _id: ObjectId('679900885b83e7325fbd11ed'), locations: [ { location: { type: \"Point\", coordinates: [ 1, 1 ] }, id: \"6799007c6bf35e2d5563d600\" }, { location: {}, id: \"6799007e6bf35e2d5563d602\" } ], createdAt: new Date(1738080392536), updatedAt: new Date(1738080392536), __v: 0 }  unknown GeoJSON type: {}"
      },
      "index": 0,
      "code": 16755
    }

Link to the code that reproduces this issue

https://github.com/devj3ns/payload-mongodb-point-field-bug

Reproduction Steps

1. Create a new empty page in the reproduction payload project
2. Add two location entries to the array
3. Fill one location entry with a valid latitude and longitude
4. Leave the second location field empty
5. Save the document.
6. You will see an error modal with the label: "Something went wrong."

Which area(s) are affected? (Select all that apply)

db-mongodb, area: core

Environment Info

Payload: 3.19.0
Node: 22.13.0
MongoDB: 8.0.3

[r1tsuu]

Hey @devj3ns, thank you for the report!
I debugged your issue, I think there's nothing much that we can do here. In MongoDB If you have a geo index on the locations.location path and you have multiple elements on that path (e.g locations is an array) they all must contain a valid GeoJSON value. This is not related to an empty object {}, undefined and null are also invalid in this case.

One thing that you could do is to have defaultValue: [0, 0] on that field and then, in your app logic treat it as a non defined value, you could even have a custom description that checks if the value is [0, 0] and says that it's not defined.
This is not ideal of course but I don't think there are any other ways for that. While we could have an implicit behavior for the defaultValue fallback, I think that will confuse users.

I'm converting this to a discussion, let me know if you don't agree with that.

[jhb-dev]

Hey @r1tsuu, thanks for the investigation and explanation, it makes sense!

I resolved the issue by adding two hooks that handle data transformation when it's undefined:

hooks: {
  beforeChange: [({ value }) => (!value ? [0, 0] : value)],
  afterRead: [({ value }) => !value || (Array.isArray(value) && value[0] === 0 && value[1] === 0) ? null : value],
},