Delete features (feature service)

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Sample viewer app

Delete features from an online feature service.

screenshot

Use case

Sometimes users may want to delete features from an online feature service.

How to use the sample

  • click on a feature on the Map
  • click on the delete button

How it works

  1. Create a ServiceFeatureTable object from a URL.
  2. Create a FeatureLayer from the service feature table.
  3. Select features from the feature layer via selectFeatures().
  4. Remove the selected features from the table using deleteFeatures().
  5. Update the table on the server using applyEdits().

Relevant API

  • Feature
  • FeatureLayer
  • ServiceFeatureTable

Tags

deletion, feature, online, Service, table

Sample Code

DeleteFeaturesFeatureService.cppDeleteFeaturesFeatureService.cppDeleteFeaturesFeatureService.hDeleteFeaturesFeatureService.qml
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// [WriteFile Name=DeleteFeaturesFeatureService, Category=EditData]
// [Legal]
// Copyright 2016 Esri.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// [Legal]

#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

#include "DeleteFeaturesFeatureService.h"

#include "Map.h"
#include "MapQuickView.h"
#include "Basemap.h"
#include "Viewpoint.h"
#include "Point.h"
#include "SpatialReference.h"
#include "ServiceFeatureTable.h"
#include "FeatureLayer.h"
#include "Feature.h"
#include "ArcGISFeature.h"
#include "FeatureEditResult.h"
#include "FeatureQueryResult.h"
#include <QUrl>
#include <QUuid>
#include <QMouseEvent>
#include <QString>
#include <memory>

using namespace Esri::ArcGISRuntime;

DeleteFeaturesFeatureService::DeleteFeaturesFeatureService(QQuickItem* parent) :
  QQuickItem(parent)
{
}

DeleteFeaturesFeatureService::~DeleteFeaturesFeatureService() = default;

void DeleteFeaturesFeatureService::init()
{
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<DeleteFeaturesFeatureService>("Esri.Samples", 1, 0, "DeleteFeaturesFeatureServiceSample");
  qmlRegisterUncreatableType<CalloutData>("Esri.Samples", 1, 0, "CalloutData", "CalloutData is an uncreatable type");
}

void DeleteFeaturesFeatureService::componentComplete()
{
  QQuickItem::componentComplete();

  // find QML MapView component
  m_mapView = findChild<MapQuickView*>("mapView");
  m_mapView->setWrapAroundMode(WrapAroundMode::Disabled);

  // create a Map by passing in the Basemap
  m_map = new Map(BasemapStyle::ArcGISStreets, this);
  m_map->setInitialViewpoint(Viewpoint(Point(-10800000, 4500000, SpatialReference(102100)), 3e7));

  // set map on the map view
  m_mapView->setMap(m_map);

  // create the ServiceFeatureTable
  m_featureTable = new ServiceFeatureTable(QUrl("https://sampleserver6.arcgisonline.com/arcgis/rest/services/DamageAssessment/FeatureServer/0"), this);

  // create the FeatureLayer with the ServiceFeatureTable and add it to the Map
  m_featureLayer = new FeatureLayer(m_featureTable, this);
  m_map->operationalLayers()->append(m_featureLayer);

  connectSignals();
}

void DeleteFeaturesFeatureService::connectSignals()
{
  // connect to the mouse clicked signal on the MapQuickView
  connect(m_mapView, &MapQuickView::mouseClicked, this, [this](QMouseEvent& mouseEvent)
  {
    // first clear the selection
    m_featureLayer->clearSelection();

    // set the properties for qml
    emit hideWindow();

    //! [DeleteFeaturesFeatureService identify feature]
    // call identify on the map view
    constexpr double tolerance = 5.0;
    constexpr int maxResults = 1;
    const double screenX = mouseEvent.x();
    const double screenY = mouseEvent.y();
    constexpr bool returnPopupsOnly = false;
    m_mapView->identifyLayer(m_featureLayer, screenX, screenY, tolerance, returnPopupsOnly, maxResults);
    //! [DeleteFeaturesFeatureService identify feature]
  });

  // connect to the viewpoint changed signal on the MapQuickView
  connect(m_mapView, &MapQuickView::viewpointChanged, this, [this]()
  {
    m_featureLayer->clearSelection();
    emit hideWindow();
  });

  // connect to the identifyLayerCompleted signal on the map view
  connect(m_mapView, &MapQuickView::identifyLayerCompleted, this, [this](QUuid, IdentifyLayerResult* rawIdentifyResult)
  {
    // Deletes rawIdentifyResult instance when we leave scope.
    auto identifyResult = std::unique_ptr<IdentifyLayerResult>(rawIdentifyResult);

    if(!identifyResult)
    {
      return;
    }

    if (identifyResult->geoElements().isEmpty())
    {
      return;
    }

    // delete selected feature member if not nullptr
    if (m_selectedFeature)
    {
      delete m_selectedFeature;
      m_selectedFeature = nullptr;
    }

    GeoElement* element = identifyResult->geoElements().at(0);
    if (!element)
    {
      return;
    }

    // select the item in the result
    QueryParameters query;
    query.setObjectIds(QList<qint64> { element->attributes()->attributeValue(QStringLiteral("objectid")).toLongLong() });
    m_featureLayer->selectFeatures(query, SelectionMode::New);

    // set selected feature member
    m_selectedFeature = static_cast<ArcGISFeature*>(element);
    // Don't delete the selected feature when the IdentityResult is deleted.
    m_selectedFeature->setParent(this);
  });

  // connect to the selectedFeatures signal on the feature layer
  connect(m_featureLayer, &FeatureLayer::selectFeaturesCompleted, this, [this](QUuid, FeatureQueryResult* rawFeatureQueryResult)
  {
    // Delete rawFeatureQueryResult pointer when we leave scope.
    auto featureQueryResult = std::unique_ptr<FeatureQueryResult>(rawFeatureQueryResult);

    FeatureIterator iter = featureQueryResult->iterator();
    if (iter.hasNext())
    {
      Feature* feat = iter.next();
      // emit signal for QML
      const QString featureType = feat->attributes()->attributeValue(QStringLiteral("typdamage")).toString();
      // Html tags used to bold and increase pt size of callout title.
      m_mapView->calloutData()->setTitle(QString("<br><b><font size=\"+2\">%1</font></b>").arg(featureType));
      m_mapView->calloutData()->setLocation(feat->geometry().extent().center());
      emit featureSelected();
    }
  });

  // connect to the deleteFeatureCompleted signal from the ServiceFeatureTable
  connect(m_featureTable, &ServiceFeatureTable::deleteFeatureCompleted, this, [this](QUuid, bool success)
  {
    // if delete feature was successful, call apply edits
    if (success)
      m_featureTable->applyEdits();
  });

  // connect to the applyEditsCompleted signal from the ServiceFeatureTable
  connect(m_featureTable, &ServiceFeatureTable::applyEditsCompleted, this, [](QUuid, const QList<FeatureEditResult*>& featureEditResults)
  {
    // obtain the first item in the list
    FeatureEditResult* featureEditResult = featureEditResults.isEmpty() ? nullptr : featureEditResults.first();
    // check if there were errors, and if not, log the new object ID
    if (featureEditResult && !featureEditResult->isCompletedWithErrors())
      qDebug() << "Successfully deleted Object ID:" << featureEditResult->objectId();
    else
      qDebug() << "Apply edits error.";

    qDeleteAll(featureEditResults);
  });
}

void DeleteFeaturesFeatureService::deleteSelectedFeature()
{
  m_featureTable->deleteFeature(m_selectedFeature);
}

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