ReadPropertyMultiple silently ignores unknown objects/properties instead of returning BACnet errors

[Danebae]

Sorry in advance if I missed something obvious; this is my first time opening an issue.

Summary

ReadPropertyMultiple currently returns an empty or partial ACK when:

• the requested object does not exist
• the requested property does not exist

Instead of returning standard BACnet errors such as:

• ErrorClass.OBJECT / ErrorCode.UNKNOWN_OBJECT
• ErrorClass.PROPERTY / ErrorCode.UNKNOWN_PROPERTY

Current behavior

In BDDevice.#onBacnetReadPropertyMultiple:

• missing objects are skipped silently

In BDObject.___readPropertyMultiple:

• missing properties are skipped silently

This produces successful ReadPropertyMultipleResponse payloads with empty or partial values arrays
instead of an error response.

Why this is a problem

This differs from the behavior of:

• ReadProperty
• SubscribeCOV

which already return proper BACnet errors for unknown objects.

For clients, this creates ambiguous behavior:

• a deleted object may look like a successful read with no data
• polling logic may count a read as successful unless extra defensive checks are added client-side

Expected behavior

For ReadPropertyMultiple:

• if a requested object does not exist, return UNKNOWN_OBJECT
• if a requested property does not exist, return UNKNOWN_PROPERTY

Minimal fix idea

In dist/objects/device/device.js

Use #getObjectByIdOrThrow(objectId) instead of silently skipping unknown objects in
#onBacnetReadPropertyMultiple.

In dist/objects/generic/object.js

Use ___getPropertyOrThrow(identifier.id) instead of silently skipping unknown properties in
___readPropertyMultiple.

Reproduction

1. Start a virtual BACnet device with one exposed object
2. Have a client read it successfully using ReadPropertyMultiple
3. Delete that object from the server
4. Perform the same ReadPropertyMultiple again

Actual result

A valid ACK is returned with no useful result data.

Expected result

A BACnet error response such as:

• ErrorClass.OBJECT / ErrorCode.UNKNOWN_OBJECT

Notes

I found this while testing a BACnet client polling a BACnet device built with this library.

In the same scenario:

• SubscribeCOV correctly returns an error for the missing object
• ReadPropertyMultiple returns an empty/partial ACK instead

So the RPM path appears inconsistent with the rest of the device behavior.

[jacoscaz]

@Danebae thank you for flagging this! I can't give you an ETA as it's been a hectic few weeks over here but I will get to this at some point. Of course, feel free to have a go at it yourself in a PR; I'd be happy to provide any guidance required, though you seem to have identified the issue and potential solutions already. Was any of this done with AI assistance? No judgement, I'm just curious.

[Danebae]

@jacoscaz yes, it was done with AI assistance.
I noticed the bug while running the app with your library and testing it with YABE. However, since I’ve never coded in TypeScript and have very limited experience with JavaScript (I’m more of a PLC programmer), I asked AI for help.

That being said, I don’t think I’m capable of fixing it myself.

By the way, thanks for such a great tool.

[jacoscaz]

By the way, thanks for such a great tool.

@Danebae I appreciate the kind words! Thank you!

I noticed the bug while running the app with your library and testing it with . However, since I’ve never coded in TypeScript and have very limited experience with JavaScript (I’m more of a PLC programmer), I asked AI for help.

Thank you for taking the time to contribute this issue and investigate the matter! This is a rather excellent use of AI, IMHO.

How critical is this for you? If it's super-urgent I might be able to slot it in somewhere next week.

[Danebae]

@jacoscaz It's not urgent at all.

The AI agent added "postinstall": "patch-package" to the package.json scripts, so now I can reinstall the patch with npm install. Everything seems to work fine in my app now.

Thanks again for your time.

In case it helps, this is the patch being applied:

@bacnet-js+device+0.6.0.patch

diff --git a/node_modules/@bacnet-js/device/dist/objects/device/device.js b/node_modules/@bacnet-js/device/dist/objects/device/device.js
index 0826ea7..dfb152f 100644
--- a/node_modules/@bacnet-js/device/dist/objects/device/device.js
+++ b/node_modules/@bacnet-js/device/dist/objects/device/device.js
@@ -199,7 +199,22 @@ export class BDDevice extends BDObject {
         if (!(type in this.#nextInstanceNumber)) {
             this.#nextInstanceNumber[type] = 1;
         }
-        object.___setIdentifier(this.#nextInstanceNumber[type]++);
+        let requestedInstance = null;
+        try {
+            requestedInstance = object.identifier.value.instance;
+        }
+        catch {
+            requestedInstance = null;
+        }
+        if (requestedInstance === null || requestedInstance === undefined) {
+            object.___setIdentifier(this.#nextInstanceNumber[type]++);
+        }
+        else {
+            this.#nextInstanceNumber[type] = Math.max(this.#nextInstanceNumber[type], requestedInstance + 1);
+        }
+        if (this.#objects.has(getObjectUID(object.identifier.value))) {
+            throw new Error('Cannot register object: duplicate object identifier');
+        }
         this.#objects.set(getObjectUID(object.identifier.value), object);
         this.#objectData.push(object.identifier);
         object.on('aftercov', this.#onChildAfterCov);
@@ -512,11 +527,9 @@ export class BDDevice extends BDObject {
             if (!header)
                 return;
             const values = [];
             for (const { objectId, properties: objProperties } of properties) {
-                const object = this.#objects.get(getObjectUID(objectId));
-                if (object) {
-                    values.push(await object.___readPropertyMultiple(objProperties));
-                }
+                const object = this.#getObjectByIdOrThrow(objectId);
+                values.push(await object.___readPropertyMultiple(objProperties));
             }
             this.#client.readPropertyMultipleResponse(header.sender, invokeId, values);
         });
diff --git a/node_modules/@bacnet-js/device/dist/objects/generic/object.js b/node_modules/@bacnet-js/device/dist/objects/generic/object.js
index 69f6e2a..3b7bc1e 100644
--- a/node_modules/@bacnet-js/device/dist/objects/generic/object.js
+++ b/node_modules/@bacnet-js/device/dist/objects/generic/object.js
@@ -194,13 +194,11 @@ export class BDObject extends AsyncEventEmitter {
         const ctx = { date: new Date() };
         const values = [];
         for (const identifier of identifiers) {
-            const property = this.#properties.get(identifier.id);
-            if (property) {
-                values.push({
-                    property: identifier,
-                    value: ensureArray(property.___readData(identifier.index, ctx))
-                });
-            }
+            const property = this.___getPropertyOrThrow(identifier.id);
+            values.push({
+                property: identifier,
+                value: ensureArray(property.___readData(identifier.index, ctx))
+            });
         }
         return { objectId: this.identifier.value, values };
     }