Can't seem to get the track information in executeAction




  • Official comment
    Andrey Terentyev

    Hello Sebastian,

    It is important to understand the structure of the mement when executeAction is executed.

    When user right-clicks an object displayed in Nx Client, he is given possibility to select an action which was declared in manifest string of plugin engine, along with additional data, of which necessity to be sent can be declared in manifest, as well.

    That means, if you want the plugin to receive extra data, this data should be declared in plugin engine's manifest.

    In your case, if you want to get 'objectTrackInfo->bestShotObjectMetadata' you need to declare 'needBestShotObjectMetadata' in 'requirements' section of manifest. For example,

    "requirements": {
       "capabilities": "needBestShotObjectMetadata"

    For greater details see 'objectActions' in  samples/stub_analytics_plugin/src/nx/vms_server_plugins/analytics/stub/engine.cpp

    Current version of your manifest does not contain such declaration, that's why executeAction does not receive 'objectTrackInfo'. This fact is indicated by 'mediaserver[20606]: objectTrackInfo: 0' in log file.

    Since objectTrackInfo is a pointer to interface the good practice is to check the pointer before referencing it.

    See implementation of 'executeAction' in the same engine.cpp. Here is a quotation:

    if (actionId == "nx.stub.addToList")
        messageToUser = std::string("Track id: ") + UuidHelper::toStdString(trackId) + "\n\n";

        if (!objectTrackInfo)

            messageToUser += "No object track info provided.\n\n";



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  • Avatar
    Evgeny Balashov

    Hi Sebastian,

    That's a good question, we will talk to developers and figure out what to do.

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  • Avatar
    Andrey Terentyev

    Hello Sebastian,

    Could you please do the following?

    1. Make sure you have video recording turned on.

    2. Turn on debug logging on the Server while your are debugging your plugin.


    Send us the logs, please.

    3. "The documentation says - if your solution needs context actions, declare them in Plugin's manifest and implement function nx::sdk::analytics::Engine::executeAction()."

    Send us manifestString() from device_agent.cpp and from engine.cpp, please.


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  • Avatar
    Sebastian Bou-Samra

    Sorry for the late reply

    1. Video recording is turned on
    2. Debug logging is turned on

    std::string Engine::manifestString() const


    // clang-format off


    "objectActions": [{

    "id": ")json" + kViewProfileAction + R"json(",

    "name": "View profile",

    "supportedObjectTypeIds": [

    ")json" + kFaceObject + R"json("




    // clang-format on

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  • Avatar
    Sebastian Bou-Samra

    Is anyone able to help me on this still? Maybe this extra information could help. 

    nx::sdk::Result<nx::sdk::analytics::IAction::Result> Engine::executeAction(

    conststd::string &actionId,

    nx::sdk::Uuid trackId,

    nx::sdk::Uuid deviceId,


    nx::sdk::Ptr<nx::sdk::analytics::IObjectTrackInfo> objectTrackInfo,

    conststd::map<std::string, std::string>&params)


    std::string actionUrl;

    NX_PRINT << __func__

    <<"\ntrackId: "<< trackId

    <<"\nobjectTrackInfoRaw: "<< objectTrackInfo

    <<"\nparamsRaw: "<<&params

    <<"\nobjectTrackInfo: "<<objectTrackInfo->track()

    <<"\nbestShotObjectMetadata: "<<objectTrackInfo->bestShotObjectMetadata()

    <<"\nformattedTrackInfo: "<<std::string("Object track info:\n") +" Track: "+objectTrackToString(objectTrackInfo->track(), trackId);


    This gives me back this log

    mediaserver[20606]: [unnamed_lib_context_engine_{f7c76ed9-f325-5498-56cf-303011d9cb16}] executeAction
    mediaserver[20606]: trackId: {AB7BB8ED-7389-4965-89CF-FE2CFC9731DF}
    mediaserver[20606]: objectTrackInfoRaw: 1
    mediaserver[20606]: paramsRaw: 0x7f1a4c0c6ff0
    mediaserver[20606]: objectTrackInfo: 0
    mediaserver[20606]: bestShotObjectMetadata: 0
    mediaserver[20606]: formattedTrackInfo: Object track info:
    mediaserver[20606]: Track: null

    Notice how i have nothing on this object track Info. This is different to the stub analytics plugin provided, where the attributes can be accessed. How do I get that information, I'm using pushMetadataPacket instead of pullMetadataPacket which is the only culprit I can think of. I'm not experienced enough in C++ to be able to understand the inner workings here, so any help would be greatly appreciated. 

    Something else I saw with the debug logs that is interesting when I click an action, is I get this:

    2019-12-10 14:18:52.155  19601   DEBUG QnExecuteAnalyticsActionRestHandler(0x7f59801247b0): The action type facerec.viewProfileAction has no addittional requirements.Track, best shot frame and position are not going to be fetched.
    It's as though I'm missing some key piece of code that will push the track info to the executeAction function. 

    Thanks again, Sebastian
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  • Avatar
    Sebastian Bou-Samra

    Thank you very much, this resolved my issue! Appreciate the detailed response

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