Feature layer (geodatabase)

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Display features from a local geodatabase.

screenshot

Use case

Accessing data from a local geodatabase is useful when working in an environment that has an inconsistent internet connection or that does not have an internet connection at all. For example, a department of transportation field worker might source map data from a local geodatabase when conducting signage inspections in rural areas with poor network coverage.

How to use the sample

Pan and zoom around the map. View the data loaded from the geodatabase.

How it works

The sample creates an instance of GeodatabaseFeatureTable by supplying the path to the local mobile geodatabase. The FeatureLayer is then supplied with the GeodatabaseFeatureTable and added to the Map. The mobile geodatabase can either be obtained through ArcMap, with the Create Runtime Content geoprocessing tool, or through a feature service with the GeodatabaseSyncTask.

  1. Create a geodatabase using the provided local resource.
  2. Get the 'Trailheads' GeodatabaseFeatureTable from the geodatabase, Geodatabase.geodatabaseFeatureTable(tableName).
  3. Create a feature layer using the table from above.
  4. Add the feature layer to the Map.

Relevant API

  • FeatureLayer
  • Geodatabase
  • GeodatabaseFeatureTable

Offline data

Read more about how to set up the sample's offline data here.

Link Local Location
Los Angeles Vector Tile Package <userhome>/ArcGIS/Runtime/Data/vtpk/LosAngeles.vtpk
Los Angeles Trailheads <userhome>/ArcGIS/Runtime/Data/geodatabase/LA_Trails.geodatabase

About the data

The sample shows trailheads in the greater Los Angeles area displayed on top of a vector tile basemap.

Additional information

One of the ArcGIS Runtime data set types that can be accessed via the local storage of the device (i.e. hard drive, flash drive, micro SD card, USB stick, etc.) is a mobile geodatabase. A mobile geodatabase can be provisioned for use in an ArcGIS Runtime application by ArcMap. The following provide some helpful tips on how to create a mobile geodatabase file:

In ArcMap, choose File > Share As > ArcGIS Runtime Content from the menu items to create the .geodatabase file (see the Creating ArcGIS Runtime content document)..

Note: You could also use the 'Services Pattern' and access the Geodatabase class via a Feature Service served up via ArcGIS Online or ArcGIS Enterprise. Instead of using the Geodatabase class to access the .geodatabase file on disk, you would use GeodatabaseSyncTask to point to a URL instead.

Tags

geodatabase, mobile, offline

Sample Code

FeatureLayer_Geodatabase.qml
                                                                                                     
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// [WriteFile Name=FeatureLayer_Geodatabase, Category=Features]
// [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]

import QtQuick 2.6
import QtQuick.Controls 2.2
import QtQuick.Layouts 1.3
import Esri.ArcGISRuntime 100.11
import Esri.ArcGISExtras 1.1

Rectangle {
    width: 800
    height: 600

    readonly property url dataPath: System.userHomePath + "/ArcGIS/Runtime/Data/"
    property string errorMessage: ""

    // Map view UI presentation at top
    MapView {
        anchors.fill: parent

        Map {
            id: map

            // set an initial viewpoint
            ViewpointCenter {
                Point {
                    x: -13214155
                    y: 4040194
                    spatialReference: SpatialReference { wkid: 3857 }
                }
                targetScale: 35e4
            }

            //! [FeatureLayer Geodatabase add basemap]
            // create a basemap from a local vector tile package
            Basemap {
                ArcGISVectorTiledLayer {
                    url: dataPath + "vtpk/LosAngeles.vtpk"
                }
            }
            //! [FeatureLayer Geodatabase add basemap]

            //! [FeatureLayer Geodatabase create]
            // create a feature layer
            FeatureLayer {
                // obtain the feature table from the geodatabase by name
                featureTable: gdb.geodatabaseFeatureTablesByTableName["Trailheads"] ?
                                  gdb.geodatabaseFeatureTablesByTableName["Trailheads"] :
                                  null

                // create the geodatabase
                Geodatabase {
                    id: gdb
                    path: dataPath + "geodatabase/LA_Trails.geodatabase"

                    onErrorChanged: errorMessage = error.message;
                }

                onErrorChanged: errorMessage = error.message;
            }
            //! [FeatureLayer Geodatabase create]

            onErrorChanged: errorMessage = error.message;
        }

        onErrorChanged: errorMessage = error.message;
    }

    Dialog {
        modal: true
        x: Math.round(parent.width - width) / 2
        y: Math.round(parent.height - height) / 2
        standardButtons: Dialog.Ok
        visible: text.length > 0
        property alias text : textLabel.text
        property alias informativeText : detailsLabel.text
        ColumnLayout {
            Text {
                id: textLabel
                text: errorMessage
            }
            Text {
                id: detailsLabel
                text: "Please consult the README.md"
            }
        }
    }
}

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