Generate a local geodatabase replica from an online feature service.
Use case
Generating geodatabase replica is the first step toward taking a feature service offline. It allows you to save features locally for offline display.
How to use the sample
Zoom to any extent. Then click the generate button to generate a geodatabase of features from a feature service filtered to the current extent. A red outline will show the extent used. The job's progress is shown while the geodatabase is generated. When complete, the map will reload with only the layers in the geodatabase, clipped to the extent.
How it works
- Create a
GeodatabaseSyncTaskwith the URL of the feature service and load it. - Create
GenerateGeodatabaseParametersspecifying the extent and whether to include attachments. - Create a
GenerateGeodatabaseJobwithgeodatabaseSyncTask.generateGeodatabaseAsync(parameters, downloadPath). Start the job withjob.start(). - When the job is done,
job.result()will return the geodatabase. Inside the geodatabase are feature tables which can be used to add feature layers to the map. - Call
syncTask.unregisterGeodatabaseAsync(geodatabase)after generation when you're not planning on syncing changes to the service.
Relevant API
- GenerateGeodatabaseJob
- GenerateGeodatabaseParameters
- Geodatabase
- GeodatabaseSyncTask
Tags
disconnected, local geodatabase, offline, replica, sync
Sample Code
MainActivity.kt
/*
* Copyright 2023 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.
*
*/
package com.esri.arcgismaps.sample.generategeodatabasereplicafromfeatureservice
import android.os.Bundle
import android.util.Log
import android.view.ViewGroup
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.lifecycleScope
import com.arcgismaps.ApiKey
import com.arcgismaps.ArcGISEnvironment
import com.arcgismaps.Color
import com.arcgismaps.data.Geodatabase
import com.arcgismaps.data.ServiceFeatureTable
import com.arcgismaps.geometry.Envelope
import com.arcgismaps.geometry.SpatialReference
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.layers.FeatureLayer
import com.arcgismaps.mapping.symbology.SimpleLineSymbol
import com.arcgismaps.mapping.symbology.SimpleLineSymbolStyle
import com.arcgismaps.mapping.view.Graphic
import com.arcgismaps.mapping.view.GraphicsOverlay
import com.arcgismaps.mapping.view.ScreenCoordinate
import com.arcgismaps.tasks.geodatabase.GenerateGeodatabaseJob
import com.arcgismaps.tasks.geodatabase.GeodatabaseSyncTask
import com.esri.arcgismaps.sample.generategeodatabasereplicafromfeatureservice.databinding.ActivityMainBinding
import com.esri.arcgismaps.sample.generategeodatabasereplicafromfeatureservice.databinding.GenerateGeodatabaseDialogLayoutBinding
import com.google.android.material.dialog.MaterialAlertDialogBuilder
import com.google.android.material.snackbar.Snackbar
import kotlinx.coroutines.launch
class MainActivity : AppCompatActivity() {
// set up data binding for the activity
private val activityMainBinding: ActivityMainBinding by lazy {
DataBindingUtil.setContentView(this, R.layout.activity_main)
}
// setup data binding for the mapview
private val mapView by lazy {
activityMainBinding.mapView
}
// starts the geodatabase replica process
private val generateButton by lazy {
activityMainBinding.generateButton
}
private val resetButton by lazy {
activityMainBinding.resetButton
}
// shows the geodatabase loading progress
private val progressDialog by lazy {
GenerateGeodatabaseDialogLayoutBinding.inflate(layoutInflater)
}
// local file path to the geodatabase
private val geodatabaseFilePath by lazy {
getExternalFilesDir(null)?.path + getString(R.string.portland_trees_geodatabase_file)
}
// keep track of the geodatabase replica generated by the feature service
private var geodatabase: Geodatabase? = null
private val downloadArea: Graphic = Graphic()
// create a Trees FeatureLayer using the first layer of the ServiceFeatureTable
private val featureLayer: FeatureLayer by lazy {
FeatureLayer.createWithFeatureTable(
featureTable = ServiceFeatureTable(
uri = application.getString(R.string.feature_server_url) + "/0"
)
)
}
// creates a graphic overlay
private val graphicsOverlay: GraphicsOverlay = GraphicsOverlay()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// authentication with an API key or named user is
// required to access basemaps and other location services
ArcGISEnvironment.apiKey = ApiKey.create(BuildConfig.API_KEY)
lifecycle.addObserver(mapView)
// create and add a map with a Topographic basemap style
val map = ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
operationalLayers.add(featureLayer)
}
// set the max map extents to that of the feature service
// representing portland area
map.maxExtent = Envelope(
-13687689.2185849,
5687273.88331375,
-13622795.3756647,
5727520.22085841,
spatialReference = SpatialReference.webMercator()
)
// configure mapview assignments
mapView.apply {
this.map = map
// add the graphics overlay to display the boundary
graphicsOverlays.add(graphicsOverlay)
}
// create a geodatabase sync task with the feature service url
// This feature service shows a web map of portland street trees,
// their attributes, as well as related inspection information
val geodatabaseSyncTask = GeodatabaseSyncTask(getString(R.string.feature_server_url))
// set the button's onClickListener
generateButton.setOnClickListener {
// start the geodatabase generation process
generateGeodatabase(geodatabaseSyncTask, map, downloadArea.geometry?.extent)
}
resetButton.setOnClickListener {
// clear any layers already on the map
map.operationalLayers.clear()
// clear all symbols drawn
graphicsOverlay.graphics.clear()
// add the download boundary
graphicsOverlay.graphics.add(downloadArea)
// add back the feature layer
map.operationalLayers.add(featureLayer)
// close the current geodatabase, if a replica was already generated
geodatabase?.close()
// show generate button
generateButton.isEnabled = true
resetButton.isEnabled = false
}
lifecycleScope.launch {
// show the error and return if map load failed
map.load().onFailure {
showError("Unable to load map")
return@launch
}
geodatabaseSyncTask.load().onFailure {
// if the metadata load fails, show the error and return
showError("Failed to fetch geodatabase metadata")
return@launch
}
// show download area once map is loaded
updateDownloadArea()
// enable the generate button since the task is now loaded
generateButton.isEnabled = true
// create a symbol to show a box around the extent we want to download
downloadArea.symbol = SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.red, 2F)
// add the graphic to the graphics overlay when it is created
graphicsOverlay.graphics.add(downloadArea)
// update the download area on viewpoint change
mapView.viewpointChanged.collect {
updateDownloadArea()
}
}
}
/**
* Displays a red border on the map to signify the [downloadArea]
*/
private fun updateDownloadArea() {
// define screen area to create replica
val minScreenPoint = ScreenCoordinate(200.0, 200.0)
val maxScreenPoint = ScreenCoordinate(
mapView.measuredWidth - 200.0,
mapView.measuredHeight - 200.0
)
// convert screen points to map points
val minPoint = mapView.screenToLocation(minScreenPoint)
val maxPoint = mapView.screenToLocation(maxScreenPoint)
// use the points to define and return an envelope
if (minPoint != null && maxPoint != null) {
val envelope = Envelope(minPoint, maxPoint)
downloadArea.geometry = envelope
}
}
/**
* Starts a [geodatabaseSyncTask] with the given [map] and [extents],
* runs a GenerateGeodatabaseJob and saves the geodatabase file into local storage
*/
private fun generateGeodatabase(
geodatabaseSyncTask: GeodatabaseSyncTask,
map: ArcGISMap,
extents: Envelope?
) {
if (extents == null) {
return showError("Download area extent is null")
}
lifecycleScope.launch {
// create generate geodatabase parameters for the selected extents
val defaultParameters =
geodatabaseSyncTask.createDefaultGenerateGeodatabaseParameters(extents).getOrElse {
// show the error and return if the task fails
showError("Error creating geodatabase parameters")
return@launch
}.apply {
// set the parameters to only create a replica of the Trees (0) layer
layerOptions.removeIf { layerOptions ->
layerOptions.layerId != 0L
}
}
// set return attachments option to false
// indicates if any attachments are added to the geodatabase from the feature service
defaultParameters.returnAttachments = false
// create a generate geodatabase job
geodatabaseSyncTask.createGenerateGeodatabaseJob(defaultParameters, geodatabaseFilePath)
.run {
// create a dialog to show the jobs progress
val materialDialogBuilder = createProgressDialog(this)
// show the dialog and obtain a reference to it
val jobProgressDialog = materialDialogBuilder.show()
// launch a progress collector to display progress
launch {
progress.collect { value ->
// update the progress bar and progress text
progressDialog.progressBar.progress = value
progressDialog.progressTextView.text = value.toString()
}
}
// start the generateGeodatabase job
start()
// if the job completed successfully, get the geodatabase from the result
val geodatabase = result().getOrElse {
// show an error and return if job failed
showError("Error fetching geodatabase: ${it.message}")
// dismiss the dialog
jobProgressDialog.dismiss()
return@launch
}
// load and display the geodatabase
loadGeodatabase(geodatabase, map)
// dismiss the dialog view
jobProgressDialog.dismiss()
// unregister since we are not syncing
geodatabaseSyncTask.unregisterGeodatabase(geodatabase)
// show reset button as the task is now complete
generateButton.isEnabled = false
resetButton.isEnabled = true
}
}
}
/**
* Loads the [replicaGeodatabase] and renders the feature layers on to the [map]
*/
private suspend fun loadGeodatabase(replicaGeodatabase: Geodatabase, map: ArcGISMap) {
// clear any layers already on the map
map.operationalLayers.clear()
// clear all symbols drawn
graphicsOverlay.graphics.clear()
// load the geodatabase
replicaGeodatabase.load().onFailure {
// if the load failed, show the error and return
showError("Error loading geodatabase")
return
}
// add all of the geodatabase feature tables to the map as feature layers
map.operationalLayers += replicaGeodatabase.featureTables.map { featureTable ->
FeatureLayer.createWithFeatureTable(featureTable)
}
// keep track of the geodatabase to close it before generating a new replica
geodatabase = replicaGeodatabase
}
/**
* Creates a new alert dialog using the progressDialog and provides
* GenerateGeodatabaseJob cancellation on dialog cancellation
*
* @param generateGeodatabaseJob the job to cancel
*
* @return returns an alert dialog
*/
private fun createProgressDialog(generateGeodatabaseJob: GenerateGeodatabaseJob): MaterialAlertDialogBuilder {
// build and return a new alert dialog
return MaterialAlertDialogBuilder(this).apply {
// setting it title
setTitle(getString(R.string.dialog_title))
// allow it to be cancellable
setCancelable(false)
// sets negative button configuration
setNegativeButton("Cancel") { _, _ ->
// cancels the generateGeodatabaseJob
lifecycleScope.launch {
generateGeodatabaseJob.cancel()
}
}
// removes parent of the progressDialog layout, if previously assigned
progressDialog.root.parent?.let { parent ->
(parent as ViewGroup).removeAllViews()
}
// set the progressDialog Layout to this alert dialog
setView(progressDialog.root)
}
}
private fun showError(message: String) {
Log.e(localClassName, message)
Snackbar.make(mapView, message, Snackbar.LENGTH_SHORT).show()
}
}