My Watcher detects replace when document is updated by mongoDB compass but not with findOneAndReplace

MongoDB Atlas App Services & Realm Atlas Device Sync
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1

This watcher that I coded (using Android app coded with java ) will detect an update using MongoDB compass but not when I run the same update from a function using a http endpoint from postman.

I don’t know why. Any help would be appreciated, Thanks.

RealmEventStreamAsyncTask<RealmLogEntry> watcher3 = mongoCollection
                        .watchWithFilterAsync(new Document("fullDocument.userId", "18"));
                watcher3.get(result3 -> {
                    try {
                        if (result3.isSuccess()) {
                            Log.v("EXAMPLE", "Event type watcher 3: " +
                                    result3.get().getOperationType() + " full document: " +
                                    result3.get().getFullDocument());
                        } else {
                            Log.e("EXAMPLE",
                                    "failed to subscribe to filtered changes in the collection with : ",
                                    result3.getError());
                        }
                    } catch (NullPointerException npe) {
                        Log.d(TAG, "onCreate: potential delete by  frig ???????");
                    }
                });

the function that I am running, that is not being detected by the watcher is :

return collection.findOneAndReplace(query, replacement, options)
            .then(replacedDocument => {
                if(replacedDocument) {
                    console.log(`Successfully replaced the following document: ${replacedDocument}.`);
                    response.setStatusCode(200); // Set an HTTP Status code like "201 - created"
                    response.setBody(JSON.stringify({  "code": 200, "message": "update ok", "timestamp": dateBob }));
                } else {
                    console.log("No document matches the provided query.")
                    response.setStatusCode(400); // Set an HTTP Status code like "201 - created"
                    response.setBody(JSON.stringify({  "code": 400, "message": "update error A", "timestamp": dateBob }));
                }
                // return updatedDocument
            })
            .catch(err => {
                    console.error(`Failed to find and replace document: ${err}`)
                    response.setStatusCode(400); // Set an HTTP Status code like "201 - created"
                    response.setBody(JSON.stringify({  "code": 400, "message": "update error B", "timestamp": dateBob }));
                }
            )
2

How are you setting up your watcher? Is it watching on all event types? And are you specifying the FullDocumentLookup field? See here: https://www.mongodb.com/docs/manual/changeStreams/#lookup-full-document-for-update-operations

The difference is likely that using Data Explorer synthesizes “Replace” events but findOneAndUpdate() synthesizes an “Update” event which will not have the FullDocument field unless you ask for it

3

Please share replacedDocument.

More or less the output line produced by

console.log(`Successfully replaced the following document: ${replacedDocument}.`);
4

Sorry, but its unhelpful.

"Successfully replaced the following document: [object Object]."
5

You seem to already know about

try with it.

6

I’ve change the function to a replaceOne to simplify:

one document was matched and updated, as expected.
It is not being detected by the watcher.


exports = async function (request, response) {
    const bodyJson = JSON.parse(request.body.text());
    console.log("json body = ", bodyJson);
    const query = {_id: BSON.ObjectId(bodyJson._id)}

    console.log("query = ", bodyJson._id);
    dateBob = new Date();

    // Replace it with a new document
    // const replacement = {
    //     "expire_log": dateBob,
    //     "locfrom" : "deleted",
    //     "remarks" : "deleted"
    // };
     
     
     const replacement = {
        "locfrom" : "deleted",
        "remarks" : "deleted"
     };
     

    try{
        response.addHeader("Content-Type", "application/json"); // Modify the response headers
        const collection = context.services.get("mongodb-atlas").db("logitxp").collection("log-entries");

        // Return the original document as it was before being replaced
        // const options = { "returnNewDocument": false };
        
        

        return collection.replaceOne(query, replacement)
            .then(replacedDocument => {
                if(replacedDocument) {
                    console.log("Successfully replaced the following document: replacedDocument = " + JSON.stringify(replacedDocument));
                    response.setStatusCode(200); // Set an HTTP Status code like "201 - created"
                    response.setBody(JSON.stringify({  "code": 200, "message": "update ok", "timestamp": dateBob }));
                } else {
                    console.log("No document matches the provided query.")
                    response.setStatusCode(400); // Set an HTTP Status code like "201 - created"
                    response.setBody(JSON.stringify({  "code": 400, "message": "update error A", "timestamp": dateBob }));
                }
                // return updatedDocument
            })
            .catch(err => {
                    console.error(`Failed to find and replace document: ${err}`)
                    response.setStatusCode(400); // Set an HTTP Status code like "201 - created"
                    response.setBody(JSON.stringify({  "code": 400, "message": "update error B", "timestamp": dateBob }));
                }
            )
    }
    catch (e) {
        console.log("catch e: ",e);
        response.setBody(JSON.stringify({  "code": 400, "message": "update error C", "timestamp": dateBob }));
    }
}



Logs:
[
  "query =  6282099a7f1e25def6383b49",
  "Successfully replaced the following document: replacedDocument = {\"matchedCount\":1,\"modifiedCount\":1}"
]
{
  "name": "log_replace_expire"
}
7

You have a watcher that filters

and you do a replaceOne with

I think that is why you watcher is not called. Your replacement document does not have a field named userId that contains the string value 18.

8

Bingo , that worked !!!

you are a star, thank you so much :grinning: :grinning: :grinning: :trophy: :star:

I’m guessing the compass update was detected because the entire document was updated.

1 Like
9

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