Support MongoDB aggregation pipelines in FDA queries

[GregorioBlazquez]

This is part of the MongoDB datasource implementation (#192), related Issue: #176

Currently, readMongoDatasourceRows and validateMongoFDAContract only supports the find query variant (collection, filter, projection). When aggregation is provided, it throws a InvalidMongoFDAContract error.

fiware-data-access/src/lib/utils/mongo.js

Line 176 in 39ad3cf

throw new FDAError(

fiware-data-access/src/lib/fda.js

Line 180 in 39ad3cf

throw new FDAError(

To do:

• Implement support for MongoDB aggregation pipelines in readMongoDatasourceRows and validateMongoFDAContract
• The aggregation field should accept a MongoDB aggregation pipeline array, e.g.:

  {
    "collection": "sensors",
    "aggregation": [
      { "$group": { "_id": "$category", "n": { "$sum": 1 } } }
    ]
  }

• Ensure filter and aggregation are mutually exclusive (validation should reject both being present)
• Consider whether to restrict certain stages like $out, $merge, etc. (document as needed)

[GregorioBlazquez]

Something like this in readMongoDatasourceRows?

} else if (hasAggregation) {
// rows = await client
//   .db(dsConfig.database)
//   .collection(collection)
//   .aggregate([
//     ...aggregation,
//     ...(limit ? [{ $limit: limit }] : []),
//   ])
//   .toArray();