Add a feature layer from a portal item

Learn how to use an ArcGIS portal item to access and display a in a .

add a feature layer from a portal item

You can host a variety of geographic data and other resources using . These portal can also define how the data is presented. A or , for example, not only defines the layers for a or , but also how layers are symbolized, the minimum and/or maximum scales at which they display, and several other properties. Likewise, a hosted feature layer contains the data for the layer and also defines the symbols and other display properties for how it is presented. When you add a map, scene, or layer from a portal item to your app, everything that has been saved with the is applied in your app. Adding portal items to your app rather than creating them programmatically saves you from writing a lot of code, and can provide consistency across apps that use the same data.

In this tutorial, you will add a hosted feature layer to display trailheads in the Santa Monica Mountains of Southern California. The hosted layer defines the trailhead locations (points) as well as the symbols used to display them.

Prerequisites

Before starting this tutorial:

  1. You need an ArcGIS Location Platform or ArcGIS Online account.

  2. Your system meets the system requirements.

  3. The ArcGIS Maps SDK for Qt, version 200.6.0 or later is installed.

  4. The Qt 6.5.6 software development framework is installed.

Steps

Open the project in Qt Creator

  1. To start this tutorial, complete the Display a map tutorial or download and unzip the solution.

  2. Open the Display_a_map project in Qt Creator.

  3. If you downloaded the solution, get an access token and set the API key.

Include header files

Your app needs the Portal and PortalItem classes to load an item hosted on ArcGIS Online and display it as a FeatureLayer in the map.

  1. In the project, open the Sources folder and open the Display_a_map.cpp file. Add the following four include statements.

    Display-a-map.cpp
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    #include "Display_a_map.h"
    #include "Map.h"
    #include "MapTypes.h"
    #include "MapQuickView.h"
    #include "Point.h"
    #include "Viewpoint.h"
    #include "SpatialReference.h"
    #include <QFuture>
    
    #include "Portal.h"
    #include "PortalItem.h"
    #include "FeatureLayer.h"
    #include "LayerListModel.h"
    

Add the trailheads feature layer to the map

You will connect to ArcGIS Online and access a hosted item (trailheads layer) using its . You can then create a FeatureLayer to display the PortalItem in the map.

  1. Create a Portal instance using the default constructor.

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      const Point center(-118.80543, 34.02700, SpatialReference::wgs84());
      const Viewpoint viewpoint(center, 100000.0);
      m_mapView->setViewpointAsync(viewpoint);
    
      Portal* portal = new Portal(this);
    
  2. Create a PortalItem that references the trailheads item ID on the Portal.

    Display-a-map.cpp
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      Portal* portal = new Portal(this);
    
      const QString itemId("2e4b3df6ba4b44969a3bc9827de746b3");
      PortalItem* portalItem = new PortalItem(portal, itemId, this);
    
  3. Create a FeatureLayer, using the PortalItem and referencing a serviceLayerId of 0 (zero). Then append this layer to the map's data layers (operational layers). Save the file.

    Display-a-map.cpp
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      const QString itemId("2e4b3df6ba4b44969a3bc9827de746b3");
      PortalItem* portalItem = new PortalItem(portal, itemId, this);
    
      FeatureLayer* trailheadsLayer = new FeatureLayer(portalItem, 0, this);
      m_map->operationalLayers()->append(trailheadsLayer);
    
    Expand

    Press Ctrl + R to run the app.

Your app should display a map with the trailheads centered on the Santa Monica Mountains. Double-click, drag, and scroll the mouse wheel over the map view to explore the map.

What's next?

Learn how to use additional API features, ArcGIS location services, and ArcGIS tools in these tutorials.

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