Executing MongoDB Aggregation Pipelines from a String in Node.js: Converting String to BSONDocument[]

Question

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I'm currently working on a Node.js application that interacts with a MongoDB database. My application needs to execute MongoDB aggregation pipelines that are stored in the database as strings. These pipelines are quite complex, including various aggregation stages such as $match, $group, and even $function for custom JavaScript operations.

Here's the workflow I'm dealing with:

The aggregation pipelines are predefined and stored in MongoDB as strings. For example, a pipeline might look like this when retrieved (simplified for clarity):

"[{ \"$match\": { \"status\": \"active\" } }, { \"$group\": { \"_id\": \"$category\", \"total\": { \"$sum\": 1 } } }]"

My Node.js application retrieves these strings from the database.

I need to execute these pipelines against their respective collections.

The challenge I'm facing is converting these string representations of aggregation pipelines into a format that MongoDB's Node.js driver can execute. I'm aware of potential security implications and am looking for a safe and efficient way to achieve this.

I've looked into manually parsing the string to JSON and handling special MongoDB types (ObjectId, $date, custom JavaScript functions in $function, etc.), but this approach seems cumbersome and error-prone, especially for more complex pipelines.

Is there an established method or best practice for handling this scenario? How can I safely and effectively convert these stored string representations into executable aggregation pipelines in Node.js?

Any advice or pointers would be greatly appreciated. Thank you in advance for your help!

Answer 1

Should be simply as

db.getCollection("collection").aggregate(JSON.parse("[{ \"$match\": { \"status\": \"active\" } }, { \"$group\": { \"_id\": \"$category\", \"total\": { \"$sum\": 1 } } }]"))

Yes, "NoSQL-Injections" would be a serious topic. Maybe better store JSON objects in your MongoDB rather than strings.