$geoNear: Misleading error message when coordinates array is invalid

[jl33-ai]

Mongoose version

^8.0.0

Description

The $geoNear aggregation stage produces a misleading error message when performing GeoJSON point queries with invalid coordinates. When the coordinates array in the near parameter is undefined or invalid (e.g. []), instead of indicating the coordinate validation issue, it incorrectly suggests there's a problem with having multiple arguments:

MongoServerError: geo near accepts just one argument when querying for a GeoJSON point. Extra field found: $maxDistance: 1337.0

This error message is confusing because:

1. The maxDistance parameter is valid and supported by $geoNear
2. The actual issue is the invalid coordinates array in the query

Steps to Reproduce

import mongoose from 'mongoose';
import {MongoMemoryServer} from 'mongodb-memory-server';


const ExampleSchema = new mongoose.Schema({});
ExampleSchema.index({location: '2dsphere'});

const User = mongoose.model('User', ExampleSchema);

async function main() {
    let mongod;
    try {
        mongod = await MongoMemoryServer.create(); // same issue occurs with real connection
        const mongoUri = mongod.getUri();

        await mongoose.connect(mongoUri);

        // create a document
        await new User({
            location: {
                type: 'Point',
                coordinates: [0, 0]
            }
        }).save();

        await User.aggregate([
            {
                $geoNear: {
                    near: {
                        type: 'Point',
                        coordinates: [],
                    },
                    distanceField: 'distance',
                    spherical: true,
                    maxDistance: 1337,
                    key: 'location',
                },
            }
        ]);
    } catch (error) {
        console.error(error.stack);
    } finally {
        await mongoose.disconnect();
        if (mongod) {
            await mongod.stop();
        }
    }
}

main();
// will throw the following:
// MongoServerError: geo near accepts just one argument when querying for a GeoJSON point. Extra field found: $maxDistance: 1337.0

Copy and paste the code into any project with Typescript and mongoose 8.x, npm i and then run the script with Node.

Note: The provided snippet uses an in-memory instance for ease of reproduction, but the behaviour is identical with a proper connection.

Expected Behaviour

The error message should clearly indicate that the coordinates array is invalid instead of suggesting the removal of a valid parameter (maxDistance).

[vkarpov15]

This error message is generated on the MongoDB server, and it looks like you already opened a ticket on MongoDB's JIRA: https://jira.mongodb.org/browse/SERVER-99611.

We won't fix this issue for await User.aggregate([...]) because Mongoose doesn't do any validation on aggregation pipeline when you call aggregate(). But we do some validation when using the aggregate chaining API, so #15206 makes it so that the following will throw a more helpful error without sending any commands to the MongoDB server

        await User.aggregate().near({
            near: {
                type: 'Point',
                coordinates: [],
            },
            distanceField: 'distance',
            spherical: true,
            maxDistance: 1337,
            key: 'location',
        });

Does that help?

[jl33-ai]

Yep, I realized my mistake but wasn't sure whether to remove this issue.

Validation on the aggregate pipeline looks good. Thank you for informing me.