Learn how to use an ArcGIS portal item to access and display a feature layer

You can host a variety of geographic data and other resources using ArcGIS Online
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:
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You need an ArcGIS Location Platform or ArcGIS Online account.
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Your system meets the system requirements.
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The ArcGIS Maps SDK for Qt, version 300.1.0 or later is installed.
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The Qt 6.8.2 software development framework or later is installed.
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The CMake build system is installed.
Develop or Download
You have two options for completing this tutorial:
Option 1: Develop the code
To start the tutorial, complete the Display a map tutorial. This creates a map to display the Santa Monica Mountains in California using the topographic basemap from the ArcGIS Basemap Styles service
Open a Qt Creator project
- Open the project you created by completing the Display a map tutorial.
- Continue with the following instructions to use an ArcGIS portal item to access and display a feature layer in a map.
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.
In the project Display_a_map > Display_a_map > Source Files folder of Qt Creator, double-click the Display_a_map.cpp file to open it. Add the following four include statements.
#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 item IDFeatureLayer to display the PortalItem in the map.
Staying in the Display_a_map.cpp file, within the setupViewpoint() method, create a Portal instance using the default constructor.
void Display_a_map::setupViewpoint(){
const Point center(-118.80543, 34.02700, SpatialReference::wgs84()); const Viewpoint viewpoint(center, 100000.0);
m_mapView->setViewpointAsync(viewpoint);
Portal* portal = new Portal(this);
}Continuing in the setupViewpoint() method, add code to create a PortalItem that references the trailheads item ID on the Portal.
void Display_a_map::setupViewpoint(){
const Point center(-118.80543, 34.02700, SpatialReference::wgs84()); const Viewpoint viewpoint(center, 100000.0);
m_mapView->setViewpointAsync(viewpoint);
Portal* portal = new Portal(this);
const QString itemId("2e4b3df6ba4b44969a3bc9827de746b3"); PortalItem* portalItem = new PortalItem(portal, itemId, this);
}Concluding in the setupViewpoint() method, add code to 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.
void Display_a_map::setupViewpoint(){
const Point center(-118.80543, 34.02700, SpatialReference::wgs84()); const Viewpoint viewpoint(center, 100000.0);
m_mapView->setViewpointAsync(viewpoint);
Portal* portal = new Portal(this);
const QString itemId("2e4b3df6ba4b44969a3bc9827de746b3"); PortalItem* portalItem = new PortalItem(portal, itemId, this);
FeatureLayer* trailheadsLayer = new FeatureLayer(portalItem, 0, this); m_map->operationalLayers()->append(trailheadsLayer);
}Set developer credentials
For the final steps of this tutorial, click the tab below that corresponds to the authentication type (API key authentication or User authentication) that you chose when you completed the Display a map tutorial.
Be sure to also provide the same authentication (API key or user authentication Client ID/Redirect URL) that you used for the Display a map tutorial.
Set the API Key
In the project Display_a_map > Display_a_map > Source Files folder of Qt Creator, double click the main.cpp file to open it. Modify the code to set the accessToken variable using your API key access token. Then save the file.
// The following methods grant an access token:
// 1. User authentication: Grants a temporary access token associated with a user's ArcGIS account. // To generate a token, a user logs in to the app with an ArcGIS account that is part of an // organization in ArcGIS Online or ArcGIS Enterprise.
// 2. API key authentication: Get a long-lived access token that gives your application access to // ArcGIS location services. Go to the tutorial at https://links.esri.com/create-an-api-key. // Copy the API Key access token.
const QString accessToken = QString("");
if (accessToken.isEmpty()) { qWarning() << "Use of ArcGIS location services, such as the basemap styles service, requires" << "you to authenticate with an ArcGIS account or set the API Key property."; } else { ArcGISRuntimeEnvironment::setApiKey(accessToken); }Best Practice: The access token is stored directly in the code as a convenience for this tutorial. Do not store credentials directly in source code in a production environment.
Set path to the Qt Toolkit in the project
In the project Display_a_map folder of Qt Creator, double-click the CMakeLists.txt file to open it. Locate the line that sets the ARCGIS_TOOLKIT_REPOSITORY variable and specify the path of the root directory of the ArcGIS Maps SDK for Qt Toolkit cloned repo that resides on your system (for example: C:/applications/arcgis-maps-sdk-toolkit-qt). If this is not correct the OAuth dialog will not appear for you to enter your user credentials. Then save the file.
# TODO: Replace the <path_to_toolkit_repo> with a valid location where the Qt Toolkit# root directory resides on your system, example: C:/applications/arcgis-maps-sdk-toolkit-qt# The code also sets the TOOLKIT_FOUND variable which is used by other parts of the tutorial.
set(ARCGIS_TOOLKIT_REPOSITORY "<path_to_toolkit_repo>")Set developer credentials in the solution
In the project Display_a_map > Display_a_map > Source Files folder of Qt Creator, double-click the Display_a_map.cpp file to open it. Set your values for the REDIRECT_URL and the CLIENT_ID strings. Then save the file.
{
#ifdef TOOLKIT_FOUND
// Define the Redirect URL string obtained when creating the OAuth credentials. // TODO: You need to replace the "REDIRECT_URL" with your own valid string, // ex: "urn:ietf:wg:oauth:2.0:oob"
const auto qStringRedirectUrl = QString{"REDIRECT_URL"};
// Define the URL of the portal to authenticate with. const QUrl qUrlPortal = QUrl{"https://www.arcgis.com/"};
// Define a unique identifier associated with an application registered with the // portal that assists with client/server OAuth authentication. // TODO: You need to replace the "CLIENT_ID" with your own valid string.
const QString qStringClientId = QString{"CLIENT_ID"};
// Create a new OAuth user configuration using: the Url to mapping web service, the Client ID // string, and the Redirect Url string. auto* oAuthUserConfiguration = new OAuthUserConfiguration(qUrlPortal, qStringClientId, qStringRedirectUrl, this);
// Call the Toolkit's OAuthUserConfigurationManager static `addConfiguration` // method to use the OAuth dialog. This will tell the Authenticator to use OAuth for the provided configuration. Toolkit::OAuthUserConfigurationManager::addConfiguration(oAuthUserConfiguration);#endif // TOOLKIT_FOUNDPress 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.
Alternatively, you can download the tutorial solution, as follows.
Option 2: Download the solution
Click the Download solution link on this page under the Solution title and unzip the file to a location on your machine.
In Qt Creator, choose File > Open File or Project… from them menus. In the Open file dialog, navigate to the CMakeLists.txt file for the solution you unzipped and click the Open button.
The Configure Project window will appear for you to specify the Qt Kit to use to compile the project. Check on the Qt Kit called Desktop Qt 6.8.2 MSVC2022 64bit before clicking the Configure Project button at the bottom of the page.
Since the downloaded solution does not contain authentication credentials (API Key or User authentication), you must set up authentication to create the developer credentials and add them to the project.
For the final steps of this tutorial, click the tab below that corresponds to the authentication type (API key authentication or User authentication) that you chose when you completed the Display a map tutorial.
Be sure to also provide the same authentication (API key or user authentication Client ID/Redirect URL) that you used for the Display a map tutorial.
Set developer credentials in the solution
Set the API Key
In the project Display_a_map > Display_a_map > Source Files folder of Qt Creator, double click the main.cpp file to open it. Modify the code to set the accessToken variable using your API key access token. Then save the file.
// The following methods grant an access token:
// 1. User authentication: Grants a temporary access token associated with a user's ArcGIS account. // To generate a token, a user logs in to the app with an ArcGIS account that is part of an // organization in ArcGIS Online or ArcGIS Enterprise.
// 2. API key authentication: Get a long-lived access token that gives your application access to // ArcGIS location services. Go to the tutorial at https://links.esri.com/create-an-api-key. // Copy the API Key access token.
const QString accessToken = QString("");
if (accessToken.isEmpty()) { qWarning() << "Use of ArcGIS location services, such as the basemap styles service, requires" << "you to authenticate with an ArcGIS account or set the API Key property."; } else { ArcGISRuntimeEnvironment::setApiKey(accessToken); }Best Practice: The access token is stored directly in the code as a convenience for this tutorial. Do not store credentials directly in source code in a production environment.
Set path to the Qt Toolkit in the project
In the project Display_a_map folder of Qt Creator, double-click the CMakeLists.txt file to open it. Locate the line that sets the ARCGIS_TOOLKIT_REPOSITORY variable and specify the path of the root directory of the ArcGIS Maps SDK for Qt Toolkit cloned repo that resides on your system (for example: C:/applications/arcgis-maps-sdk-toolkit-qt). If this is not correct the OAuth dialog will not appear for you to enter your user credentials. Then save the file.
# TODO: Replace the <path_to_toolkit_repo> with a valid location where the Qt Toolkit# root directory resides on your system, example: C:/applications/arcgis-maps-sdk-toolkit-qt# The code also sets the TOOLKIT_FOUND variable which is used by other parts of the tutorial.
set(ARCGIS_TOOLKIT_REPOSITORY "<path_to_toolkit_repo>")Set developer credentials in the solution
In the project Display_a_map > Display_a_map > Source Files folder of Qt Creator, double-click the Display_a_map.cpp file to open it. Set your values for the REDIRECT_URL and the CLIENT_ID strings. Then save the file.
{
#ifdef TOOLKIT_FOUND
// Define the Redirect URL string obtained when creating the OAuth credentials. // TODO: You need to replace the "REDIRECT_URL" with your own valid string, // ex: "urn:ietf:wg:oauth:2.0:oob"
const auto qStringRedirectUrl = QString{"REDIRECT_URL"};
// Define the URL of the portal to authenticate with. const QUrl qUrlPortal = QUrl{"https://www.arcgis.com/"};
// Define a unique identifier associated with an application registered with the // portal that assists with client/server OAuth authentication. // TODO: You need to replace the "CLIENT_ID" with your own valid string.
const QString qStringClientId = QString{"CLIENT_ID"};
// Create a new OAuth user configuration using: the Url to mapping web service, the Client ID // string, and the Redirect Url string. auto* oAuthUserConfiguration = new OAuthUserConfiguration(qUrlPortal, qStringClientId, qStringRedirectUrl, this);
// Call the Toolkit's OAuthUserConfigurationManager static `addConfiguration` // method to use the OAuth dialog. This will tell the Authenticator to use OAuth for the provided configuration. Toolkit::OAuthUserConfigurationManager::addConfiguration(oAuthUserConfiguration);#endif // TOOLKIT_FOUNDRun the solution
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.