ArcGIS Knowledge Graphs

Use this skill for working with knowledge graphs, graph queries, and relationship visualization.

Knowledge Graph Service

Fetch Knowledge Graph

import KGModule from "@arcgis/core/rest/knowledgeGraphService.js";

const url = "https://your-server/server/rest/services/Hosted/YourKG/KnowledgeGraphServer";
const knowledgeGraph = await KGModule.fetchKnowledgeGraph(url);

console.log("Graph name:", knowledgeGraph.name);
console.log("Entity types:", knowledgeGraph.dataModel.entityTypes);
console.log("Relationship types:", knowledgeGraph.dataModel.relationshipTypes);

KnowledgeGraphLayer

Add to Map

import KnowledgeGraphLayer from "@arcgis/core/layers/KnowledgeGraphLayer.js";

const kgLayer = new KnowledgeGraphLayer({
  url: "https://your-server/server/rest/services/Hosted/YourKG/KnowledgeGraphServer"
});

await kgLayer.load();
map.add(kgLayer);

Configure Sublayers

const kgLayer = new KnowledgeGraphLayer({
  url: "...",
  // Only include specific entity types
  inclusionModeDefinition: {
    generateAllSublayers: false,
    namedTypeDefinitions: new Map([
      ["Person", { useAllData: true }],
      ["Location", { useAllData: true }]
    ])
  }
});

Querying with openCypher

Basic Query

import KGModule from "@arcgis/core/rest/knowledgeGraphService.js";

const result = await KGModule.executeQuery(knowledgeGraph, {
  openCypherQuery: "MATCH (n:Person) RETURN n LIMIT 10"
});

console.log("Results:", result.resultRows);

Streaming Query (Large Results)

const queryResults = await KGModule.executeQueryStreaming(knowledgeGraph, {
  openCypherQuery: "MATCH (n:Person)-[r]->(m) RETURN n, r, m"
});

// Read stream
const reader = queryResults.resultRowsStream.getReader();

while (true) {
  const { done, value } = await reader.read();
  if (done) break;

  // Process chunk
  value.forEach(row => {
    console.log("Row:", row);
  });
}

Spatial Query with Bind Parameters

import KGModule from "@arcgis/core/rest/knowledgeGraphService.js";
import Polygon from "@arcgis/core/geometry/Polygon.js";

// Create geometry for spatial filter
const searchArea = new Polygon({
  rings: [[
    [-76, 45],
    [-70, 45],
    [-70, 40],
    [-76, 40],
    [-76, 45]
  ]]
});

const queryResults = await KGModule.executeQueryStreaming(knowledgeGraph, {
  openCypherQuery: `
    MATCH path=(a:User)-[]->(b:Observation)
    WHERE esri.graph.ST_Intersects($geometry, b.shape)
    RETURN path
  `,
  bindParameters: {
    geometry: searchArea
  }
});

Query with Filters

// Filter by property
const result = await KGModule.executeQuery(knowledgeGraph, {
  openCypherQuery: `
    MATCH (p:Person)
    WHERE p.age > 30 AND p.name CONTAINS 'John'
    RETURN p
  `
});

// Query relationships
const result = await KGModule.executeQuery(knowledgeGraph, {
  openCypherQuery: `
    MATCH (p:Person)-[r:WORKS_AT]->(c:Company)
    WHERE c.name = 'Esri'
    RETURN p.name, r.startDate, c.name
  `
});

Link Chart Visualization

Create Link Chart

import WebLinkChart from "@arcgis/core/WebLinkChart.js";
import LinkChartView from "@arcgis/core/views/LinkChartView.js";
import LinkChartLayer from "@arcgis/core/layers/LinkChartLayer.js";

const linkChartLayer = new LinkChartLayer({
  url: "https://your-server/.../KnowledgeGraphServer"
});

const linkChart = new WebLinkChart({
  layers: [linkChartLayer]
});

const linkChartView = new LinkChartView({
  container: "linkChartDiv",
  map: linkChart
});

LinkChartView Configuration

const linkChartView = new LinkChartView({
  container: "linkChartDiv",
  map: linkChart,

  // Enable interaction
  highlightOptions: {
    color: [0, 255, 255, 1],
    haloColor: [0, 255, 255, 0.5],
    haloOpacity: 0.8
  },

  // Navigation
  navigation: {
    mouseWheelZoomEnabled: true,
    browserTouchPanEnabled: true
  }
});

// View events
linkChartView.on("click", async (event) => {
  const response = await linkChartView.hitTest(event);
  if (response.results.length > 0) {
    const graphic = response.results[0].graphic;
    console.log("Clicked:", graphic.attributes);
  }
});

// Watch for selection changes
linkChartView.on("selection-change", (event) => {
  console.log("Selected entities:", event.added);
  console.log("Deselected entities:", event.removed);
});

Link Chart Component

<arcgis-link-chart>
  <arcgis-legend slot="top-right"></arcgis-legend>
  <arcgis-zoom slot="bottom-right"></arcgis-zoom>
</arcgis-link-chart>

<script type="module">
  const linkChartComponent = document.querySelector("arcgis-link-chart");
  await linkChartComponent.componentOnReady();

  const lcView = linkChartComponent.view;
  const linkChart = lcView.map;

  // Add records to link chart
  linkChart.addRecords([
    { id: "entity1", typeName: "Person" },
    { id: "entity2", typeName: "Company" }
  ]);
</script>

Link Chart Layout Settings

// Access layout settings
const layoutSettings = linkChart.layoutSettings;

// Organic Layout (default)
linkChart.layoutSettings = {
  type: "organic",
  avoidLabelOverlap: true,
  compactness: 0.5,        // 0-1, how tightly packed
  orientation: "top-to-bottom"  // top-to-bottom, bottom-to-top, left-to-right, right-to-left
};

// Chronological Layout
linkChart.layoutSettings = {
  type: "chronological",
  dateField: "timestamp",
  groupByField: "category",
  orientation: "horizontal",  // horizontal, vertical
  showTimeline: true
};

OrganicLayoutSettings

import OrganicLayoutSettings from "@arcgis/core/webdoc/applicationProperties/OrganicLayoutSettings.js";

const organicLayout = new OrganicLayoutSettings({
  avoidLabelOverlap: true,
  compactness: 0.6,
  componentLayoutEnabled: true,
  deterministic: true,
  minimumNodeDistance: 50,
  orientation: "top-to-bottom",
  preferredEdgeLength: 100,
  starSubstructureEnabled: true,
  treeSubstructureEnabled: true
});

linkChart.layoutSettings = organicLayout;

ChronologicalLayoutSettings

import ChronologicalLayoutSettings from "@arcgis/core/webdoc/applicationProperties/ChronologicalLayoutSettings.js";

const chronoLayout = new ChronologicalLayoutSettings({
  dateField: "event_date",
  groupByField: "event_type",
  orientation: "horizontal",
  showTimeline: true,
  timelinePosition: "bottom",
  sortOrder: "ascending"  // ascending, descending
});

linkChart.layoutSettings = chronoLayout;

LinkChartLayoutSwitcher Widget

import LinkChartLayoutSwitcher from "@arcgis/core/widgets/LinkChartLayoutSwitcher.js";

const layoutSwitcher = new LinkChartLayoutSwitcher({
  view: linkChartView,
  layouts: [
    {
      name: "Organic",
      settings: new OrganicLayoutSettings({ compactness: 0.5 })
    },
    {
      name: "Timeline",
      settings: new ChronologicalLayoutSettings({ dateField: "date" })
    }
  ]
});

linkChartView.ui.add(layoutSwitcher, "top-right");

Non-Spatial Data Display

// Configure non-spatial display for entities
const linkChartLayer = new LinkChartLayer({
  url: "...",
  nonspatialDataDisplay: {
    entityTypes: {
      Person: {
        displayField: "name",
        symbol: {
          type: "simple-marker",
          color: "blue",
          size: 20
        }
      },
      Company: {
        displayField: "company_name",
        symbol: {
          type: "simple-marker",
          color: "green",
          size: 25
        }
      }
    },
    relationshipTypes: {
      WORKS_AT: {
        symbol: {
          type: "simple-line",
          color: "gray",
          width: 2
        }
      }
    }
  }
});

Adding and Removing Records

// Add records
await linkChart.addRecords([
  { id: "person-1", typeName: "Person" },
  { id: "company-1", typeName: "Company" },
  { id: "rel-1", typeName: "WORKS_AT" }
]);

// Remove records
await linkChart.removeRecords([
  { id: "person-1", typeName: "Person" }
]);

// Clear all records
await linkChart.removeAllRecords();

// Get current records
const records = linkChart.records;
console.log("Current entities:", records.entities);
console.log("Current relationships:", records.relationships);

Update Link Chart from Query Results

async function updateLinkChart(queryResults, linkChart) {
  const reader = queryResults.resultRowsStream.getReader();

  while (true) {
    const { done, value } = await reader.read();
    if (done) break;

    const records = [];
    for (const row of value) {
      for (const record of row[0].path) {
        records.push({
          id: record.id,
          typeName: record.typeName
        });
      }
    }

    linkChart.addRecords(records);
  }
}

Expand/Collapse Entities

// Expand entity to show connections
await linkChart.expand({
  ids: ["entity-id"],
  typeName: "Person",
  relationshipTypes: ["KNOWS", "WORKS_AT"],
  direction: "both"  // outgoing, incoming, both
});

// Collapse entity
await linkChart.collapse({
  ids: ["entity-id"],
  typeName: "Person"
});

Selection and Highlighting

// Select entities programmatically
linkChartView.select([
  { id: "person-1", typeName: "Person" },
  { id: "person-2", typeName: "Person" }
]);

// Clear selection
linkChartView.clearSelection();

// Highlight (temporary visual emphasis)
const highlightHandle = linkChartView.highlight([
  { id: "person-1", typeName: "Person" }
]);

// Remove highlight
highlightHandle.remove();

// Go to specific entities
linkChartView.goTo([
  { id: "person-1", typeName: "Person" }
]);

WebLinkChart Properties

import WebLinkChart from "@arcgis/core/WebLinkChart.js";

const webLinkChart = new WebLinkChart({
  // Portal item (load existing)
  portalItem: { id: "LINKCHART_ID" },

  // Or create from scratch
  layers: [linkChartLayer],

  // Layout settings
  layoutSettings: organicLayout,

  // Initial records
  initialRecords: {
    entities: [
      { id: "entity-1", typeName: "Person" }
    ],
    relationships: []
  }
});

// Save to portal
await webLinkChart.saveAs({
  title: "My Link Chart",
  snippet: "Visualization of entity relationships"
});

Search Knowledge Graph

import KGModule from "@arcgis/core/rest/knowledgeGraphService.js";

const searchResults = await KGModule.executeSearch(knowledgeGraph, {
  searchQuery: "John Smith",
  typeCategoryFilter: "entity", // or "relationship", "both"
  typeNames: ["Person", "Employee"],
  returnSearchContext: true
});

searchResults.results.forEach(result => {
  console.log("Found:", result.typeName, result.id);
  console.log("Context:", result.searchContext);
});

Apply Edits

import KGModule from "@arcgis/core/rest/knowledgeGraphService.js";

// Add entity
const addResult = await KGModule.executeApplyEdits(knowledgeGraph, {
  entityAdds: [{
    typeName: "Person",
    properties: {
      name: "Jane Doe",
      age: 28
    }
  }]
});

// Update entity
const updateResult = await KGModule.executeApplyEdits(knowledgeGraph, {
  entityUpdates: [{
    typeName: "Person",
    properties: {
      globalId: "{existing-global-id}",
      age: 29
    }
  }]
});

// Delete entity
const deleteResult = await KGModule.executeApplyEdits(knowledgeGraph, {
  entityDeletes: [{
    typeName: "Person",
    ids: ["{global-id-to-delete}"]
  }]
});

// Add relationship
const relResult = await KGModule.executeApplyEdits(knowledgeGraph, {
  relationshipAdds: [{
    typeName: "WORKS_AT",
    properties: {
      originGlobalId: "{person-global-id}",
      destinationGlobalId: "{company-global-id}",
      startDate: new Date()
    }
  }]
});

Data Model

// Access data model
const dataModel = knowledgeGraph.dataModel;

// Entity types
dataModel.entityTypes.forEach(entityType => {
  console.log("Entity:", entityType.name);
  console.log("Properties:", entityType.properties);
});

// Relationship types
dataModel.relationshipTypes.forEach(relType => {
  console.log("Relationship:", relType.name);
  console.log("Origin:", relType.originEntityTypes);
  console.log("Destination:", relType.destinationEntityTypes);
});

Common openCypher Patterns

-- Find all entities
MATCH (n) RETURN n

-- Find specific type
MATCH (p:Person) RETURN p

-- Find relationships
MATCH (a)-[r]->(b) RETURN a, r, b

-- Find path
MATCH path = (a:Person)-[:KNOWS*1..3]->(b:Person)
WHERE a.name = 'John'
RETURN path

-- Aggregate
MATCH (p:Person)-[:WORKS_AT]->(c:Company)
RETURN c.name, COUNT(p) as employeeCount

-- Spatial filter
MATCH (loc:Location)
WHERE esri.graph.ST_Intersects($geometry, loc.shape)
RETURN loc

Common Pitfalls

1. Authentication required: Knowledge graph services typically require authentication

2. Streaming for large results: Use executeQueryStreaming for queries that may return many results

3. Geometry conversion: Convert geometries to WGS84 before using in spatial queries

4. Case sensitivity: openCypher property names are case-sensitive