An array of analysis and tracing options usually begin with or include a utility element in the result. This element corresponds to a network feature or object that contains additional information such as a terminal or fraction along value that affects the analysis. For example, the utility element's terminal may limit the number of connectivity associations or change the direction of a trace, while its fraction along value may return a partial geometry from a trace.
This utility element may be created from a feature or asset type with a global id. The feature may be a result of a query or identify operation on a layer or table that is part of the utility network.
Utility element from a feature
You may query for a specific feature using any of its fields or geometry or interactively identify a feature in a map view. When using identify, the feature may be found in the GeoElement list immediately under IdentifyLayerResult when part of a FeatureLayer or from sublayerResults when part of a SubtypeFeatureLayer.
final query = QueryParameters()
..whereClause = "GlobalId like '{D353C10C-E617-4618-BDD0-B48EDB822D07}'";
final queryResult = await table.queryFeatures(query);
if (queryResult.features().isEmpty) return;
final feature = queryResult.features().first as ArcGISFeature;
final identifyLayerResults = await _mapViewController.identifyLayers(
screenPoint: position,
tolerance: 5,
returnPopupsOnly: false,
);
ArcGISFeature? sublayerFeature;
ArcGISFeature? feature;
for (final layerResult in identifyLayerResults) {
if (layerResult.layerContent is SubtypeFeatureLayer) {
for (final subLayerResult in layerResult.sublayerResults) {
for (final geoElement in subLayerResult.geoElements) {
sublayerFeature = geoElement as ArcGISFeature;
}
}
} else if (layerResult.layerContent is FeatureLayer) {
for (final geoElement in layerResult.geoElements) {
feature = geoElement as ArcGISFeature;
}
}
}
await feature.load();
final element = _utilityNetwork.createElement(arcGISFeature: feature);
Utility element from an asset type
An asset type can come from another utility element or be derived from a feature in the utility network, except from a subnet line table that does not have an asset type. You can use the feature's table name to get its network source. Use the network source and the feature's subtype to get its asset group. From the asset group, you can select an asset type by name or code.
var assetType = otherElement.assetType;
var element = _utilityNetwork.createElementWithAssetType(
assetType,
globalId: globalId,
);
final tableName = feature.featureTable?.tableName;
if (tableName == null) return;
var networkSource = _utilityNetwork.definition?.getNetworkSource(tableName);
final subtypeName = feature.getFeatureSubtype()?.name;
if (subtypeName == null) return;
var assetGroup = networkSource?.getAssetGroup(subtypeName);
if (assetGroup == null) return;
final assetTypeCode = feature.attributes['ASSETTYPE'] as int;
assetType =
assetGroup.assetTypes.firstWhere((t) => t.code == assetTypeCode);
networkSource = _utilityNetwork.definition
?.getNetworkSource('Electric Distribution Device');
assetGroup = networkSource?.getAssetGroup('Service Point');
assetType =
assetGroup?.getAssetType('Single Phase Low Voltage Meter') ?? assetType;
element = _utilityNetwork.createElementWithAssetType(
assetType,
globalId: globalId,
);
Utility element properties
A terminal is required when a UtilityElement that supports more than one terminal is used in a trace and optional when used to get associations. Terminals impact traces and connectivity associations.
if (element.assetType.terminalConfiguration!.terminals.isNotEmpty) {
element.terminal =
element.assetType.terminalConfiguration!.terminals.first;
}
If the feature represents a line, you can optionally specify a location along the line to use as a trace location. This value is a percentage of the length of the line, beginning from the line's 'from' point.
Use UtilityElement.fractionAlongEdge to define the location of the point along the line.
The following example uses the GeometryEngine to get the fraction of a tap location along the line.
if (element.networkSource?.sourceType == UtilityNetworkSourceType.edge &&
feature.geometry is Polyline) {
var line = feature.geometry as Polyline;
if (line.hasZ) {
final line2 = GeometryEngine.removeZ(line) as Polyline?;
if (line2 != null) line = line2;
}
if (mapPoint.spatialReference != null &&
line.spatialReference != mapPoint.spatialReference) {
final projectedLine = GeometryEngine.project(
line,
outputSpatialReference: mapPoint.spatialReference!,
) as Polyline?;
if (projectedLine != null) line = projectedLine;
}
final percentAlong = GeometryEngine.fractionAlong(
line: line,
point: mapPoint,
tolerance: double.nan,
);
if (!percentAlong.isNaN) {
element.fractionAlongEdge = percentAlong;
}
}