MongoDB Plugin Returns Array Data as Object Format Instead of Standard JSON Array

[jeanfliu]

Hello,

I'm encountering an issue with the MongoDB plugin. When I run an aggregation query in Grafana, array data is returned in an object format rather than as a standard JSON array. Here’s an example:

• Expected Output (e.g., from MongoDB in Robot 3T):

  ["a", "b"]

  or

  [1, 2, 3, 4]

• Actual Output (from this plugin in Grafana):

  { "0": "a", "1": "b" } 

  or

  {
  "0": { "$numberDouble": "1.0" },
  "1": { "$numberDouble": "2.0" },
  "2": { "$numberDouble": "3.0" },
  "3": { "$numberDouble": "4.0" }
  }

  

Steps to Reproduce:

1. Insert sample data in MongoDB:

   db.demoColl.insertMany([
   { "name": "series_1", "datas": ["a", "b"] },
   { "name": "series_2", "datas": [1, 2, 3, 4] }
   ])

2. Execute the following aggregation query in Grafana:

   db.demoColl.aggregate([{ "$project": { "_id": 0 } }])

Environment:

• Grafana version: v11.1.0
• MongoDB plugin version: v0.1.1

The plugin currently returns array data in an object format, with each array element indexed as a key-value pair. Numeric values are wrapped in $numberDouble, which complicates direct usage within Grafana.

If the data source could return array data in a standard JSON array format, it could improve consistency and make data handling easier within Grafana.

Thanks for your work on this! Looking forward to your thoughts!

[haohanyang]

Good catch. I just realized a better way to unmarshall raw values

var a json.RawMessage
bson.UnmarshalValue(bson.TypeArray, rawValue.Value, &a)

or

var a json.RawMessage
bson.UnmarshalValue(bson.TypeEmbeddedDocument, rawValue.Value, &a)

I will soon fix it