topic How do I use a local server to access the feature tables in a local File Geodatabase so that I can query and instantiate Feature objects? in Qt Maps SDK Questions

How do I use a local server to access the feature tables in a local File Geodatabase so that I can query and instantiate Feature objects?

OrestHalustchak — Fri, 01 Feb 2019 16:25:00 GMT

I'm trying to determine how to access a File Geodatabase using the C++ Qt Runtime API. According to the information on this page, https://developers.arcgis.com/qt/latest/cpp/guide/supported-geodatabase-formats.htm, that should be possible if I use a local server.

What I need to be able to do is access the feature tables in the FGDB. If I can get to the point where I can instantiate an ArcGISFeatureTable class, then I know from there how to use queryFeatures() to get Feature objects, which is what I'm ultimately trying to do. I also am interested in editing those objects. The ArcGISFeatureTable class allow me to add, update, or delete features.

I know how to get the local server started. But, from that point, it's not clear from the documentation how actually to get the feature tables. I looked at the example called DynamicWorkspaceShapefile (https://github.com/Esri/arcgis-runtime-samples-qt/tree/master/ArcGISRuntimeSDKQt_CppSamples/LocalServer/DynamicWorkspaceShapefile) thinking that it would do something similar except with shp files. However, the example does not actually access the feature classes directly. It creates a map service and generates an image. I looked at the pattern of defining a FileGeodatabaseWorkspace (instead of a ShapefileWorkspace) and then a TableSubLayerSource, but it didn't seem to help me get to ArcGISFeatureTables.

An immediate issue is that this approach requires a LocalFeatureService to be created which needs a map package (.mpk) file. In my case, I don't have a map and don't need a map. However, to try that approach I did get as far as using ArcMap to create a map package (.mpk) file from a map created from file gdb tables. I figured that from the local feature service, I could get a url that I could use for creating a ServiceFeatureTable. Unfortunately, when I tried to load a local feature service defined from that mpk file, I got a load failed (not sure why yet, the errorOccurred signal wasn't triggered). Even if that had worked, it still would have been a round about way that accessed a packaged copy of the data and not a direct way to access the original fgdb.

So, my question is how do I use the local server to access the feature tables in a local fgdb so that I can instantiate Feature objects?

Regards.

Re: How do I use a local server to access the feature tables in a local File Geodatabase so that I can query and instantiate Feature objects?

LucasDanzinger — Wed, 06 Feb 2019 15:30:16 GMT

The general workflow in the shapefile dynamic workspace sample should be what you follow for the file geodatabase - arcgis-runtime-samples-qt/DynamicWorkspaceShapefile.cpp at master · Esri/arcgis-runtime-samples-qt · GitHub

The general workflow is:

create LocalMapService from blank MPK. You can use the one provided in the sample (https://www.arcgis.com/home/item.html?id=ea619b4f0f8f4d108c5b87e90c1b5be0 ). This doesn't mean you will need a map, it is just an intermediate step needed to start up a local map service.
Create a FileGeodatabaseWorkspace FileGeodatabaseWorkspace Class | ArcGIS for Developers
Create TableSublayerSource
Set the dynamic workspace on the LocalMapService
Start the service
Once the service starts, you should see REST endpoints to Map Services that are spun up
Create a ServiceFeatureTable by pointing to these REST endpoint URLs
You can then query the ServiceFeatureTable

Re: How do I use a local server to access the feature tables in a local File Geodatabase so that I can query and instantiate Feature objects?

OrestHalustchak — Wed, 06 Feb 2019 18:50:31 GMT

Thanks Lucas.

When I tried those steps, I got a map service started but only the simple point layer from the mpk seems to be there. I think I'm missing a step of what to do with the TableSubLayerSource that I created.

Here is the code that I'm using.

char* path = "E:/WaterNetwork/UtilityNetworkEditingAndAnalysisA4W/MapsandGeodatabase/WaterUtilities.gdb";
pkgPath = QDir::homePath() + "/ArcGIS/Runtime/Data/mpk/mpk_blank.mpk";

FileGeodatabaseWorkspace* fgdbWorkspace = new FileGeodatabaseWorkspace("fgdb_wkspc", path, this);
TableSublayerSource* source = new TableSublayerSource(fgdbWorkspace->id(), path, this);

LocalMapService* localMapServ = new LocalMapService(pkgPath, this);

    QList<DynamicWorkspace*> dynamicWorkspaces;
    dynamicWorkspaces.append(fgdbWorkspace);
    localMapServ->setDynamicWorkspaces(dynamicWorkspaces);

    connect(localMapServ, &LocalMapService::statusChanged, this, [&]()
    {
        if (localMapServ->status() == LocalServerStatus::Started)
        {
            qDebug() << "Local map service started, url =" << localMapServ->url();

// Add code here to create a ServiceFeatureTable by pointing to these REST endpoint URLs

            emit localMapServLoadDone();
        }
        else if (localMapServ->status() == LocalServerStatus::Failed)
        {
            qDebug() << "Local map service failed";
            emit localMapServLoadDone();
        }

});

    connect(localMapServ, &LocalMapService::errorOccurred, this, [&](Esri::ArcGISRuntime::Error error)
    {
        if (!error.isEmpty())
        {
            qDebug() << "Error on Local Map Service Start:" << error.message();
            showArcGISErrorMsg(error);
        }
    });

localMapServ->start();

What do I need to do at the point where I have the comment about create ServiceFeatureTable? It seems that somewhere I need to do more with the TableSubLayerSource object.

From the above code, the map service url is http://127.0.0.1:50000/qpDB90/arcgis/rest/services/mpk_blank.mpk/MapServer .

Thanks,

Orest.

Re: How do I use a local server to access the feature tables in a local File Geodatabase so that I can query and instantiate Feature objects?

JessicaTalbot1 — Fri, 19 Jun 2020 03:36:32 GMT

This is where you would create an ArcGISMapImageLayer from the LocalMapService url, an ArcGISMapImageSublayer from the TableSublayerSource, and append ArcGISMapImageSublayer to ArcGISMapImageLayer::mapImageSublayers(). However, the TableSubLayerSource represents a single table or feature class, correct? If the file gdb contains multiple tables, how do you iterate through them??

Re: How do I use a local server to access the feature tables in a local File Geodatabase so that I can query and instantiate Feature objects?

JessicaTalbot1 — Fri, 26 Jun 2020 07:24:04 GMT

A TableSubLayerSource represents a single table or feature class, correct? If the file gdb contains multiple tables/feature classes, how do you interrogate the gdb to see what’s inside? Do you need to create a TableSubLayerSource for each feature class?