ArcGIS Pro 3.3 API Reference Guide
ArcGIS.Core.Data.Knowledge Namespace / KnowledgeGraphObjectValue Class / Item Property
The key whose corresponding value will be returned or set.
Example

In This Topic
    Item Property (KnowledgeGraphObjectValue)
    In This Topic
    Gets and sets the value corresponding to the given key. This method must be called on the MCT. Use QueuedTask.Run.
    Syntax
    public virtual object this[ 
       string key
    ]; {get; set;}
    Public Overridable Default Property Item( _
       ByVal key As String _
    ) As Object

    Parameters

    key
    The key whose corresponding value will be returned or set.

    Property Value

    The value corresponding to the given key
    Exceptions
    ExceptionDescription
    This method or property must be called within the lambda passed to QueuedTask.Run.
    Invalid value type
    key cannot be null or empty string
    Remarks
    The value can be a primitive value (number, string, date, etc), a geometry, or another KnowledgeGraphValue. Note: To store a list or array, convert it to a KnowledgeGraphArrayValue first. Null values are valid. A null value will be automatically converted to a System.DBNull
    Example
    Process a KnowledgeGraphRow Value
    //Base class for entities and relationships
    //(including documents and provenance)
    public void ProcessGraphNamedObjectValue(
      KnowledgeGraphNamedObjectValue kg_named_obj_val)
    {
      if (kg_named_obj_val is KnowledgeGraphEntityValue kg_entity)
      {
        var label = kg_entity.GetLabel();
        //TODO - use label
      }
      else if (kg_named_obj_val is KnowledgeGraphRelationshipValue kg_rel)
      {
        var has_entity_ids = kg_rel.GetHasRelatedEntityIDs();
        if (kg_rel.GetHasRelatedEntityIDs())
        {
          var origin_id = kg_rel.GetOriginID();
          var dest_id = kg_rel.GetDestinationID();
          //TODO - use ids
        }
      }
      var id = kg_named_obj_val.GetID();
      var oid = kg_named_obj_val.GetObjectID();
      //Note: Typename corresponds to the name of the feature class or table
      //in the relational gdb model -and- to the name of the KnowledgeGraphNamedObjectType
      //in the knowledge graph data model
      var type_name = kg_named_obj_val.GetTypeName();
      //TODO use id, object id, etc.
    }
    
    //Object values include entities, relationships, and anonymous objects
    public void ProcessGraphObjectValue(KnowledgeGraphObjectValue kg_obj_val)
    {
      switch (kg_obj_val)
      {
        case KnowledgeGraphEntityValue kg_entity:
          ProcessGraphNamedObjectValue(kg_entity);
          break;
        case KnowledgeGraphRelationshipValue kg_rel:
          ProcessGraphNamedObjectValue(kg_rel);
          break;
        default:
          //Anonymous objects
          break;
      }
      //graph object values have a set of properties (equivalent
      //to a collection of key/value pairs)
      var keys = kg_obj_val.GetKeys();
      foreach (var key in keys)
        ProcessKnowledgeGraphRowValue(kg_obj_val[key]);//Recurse
    }
    
    //Process a KnowledgeGraphValue from a query or search
    public void ProcessGraphValue(KnowledgeGraphValue kg_val)
    {
      switch (kg_val)
      {
        case KnowledgeGraphPrimitiveValue kg_prim:
          //KnowledgeGraphPrimitiveValue not currently used in
          //query and search 
          ProcessKnowledgeGraphRowValue(kg_prim.GetValue());//Recurse
          return;
        case KnowledgeGraphArrayValue kg_array:
          var count = kg_array.GetSize();
          //Recursively process each value in the array
          for (ulong i = 0; i < count; i++)
            ProcessKnowledgeGraphRowValue(kg_array[i]);//Recurse
          return;
        case KnowledgeGraphPathValue kg_path:
          //Entities
          var entity_count = kg_path.GetEntityCount();
          //Recursively process each entity value in the path
          for (ulong i = 0; i < entity_count; i++)
            ProcessGraphObjectValue(kg_path.GetEntity(i));//Recurse
    
          //Recursively process each relationship value in the path
          var relate_count = kg_path.GetRelationshipCount();
          for (ulong i = 0; i < relate_count; i++)
            ProcessGraphObjectValue(kg_path.GetRelationship(i));//Recurse
          return;
        case KnowledgeGraphObjectValue kg_object:
          ProcessGraphObjectValue(kg_object);//Recurse
          return;
        default:
          var type_string = kg_val.GetType().ToString();
          System.Diagnostics.Debug.WriteLine(
            $"Unknown: '{type_string}'");
          return;
      }
    }
    
    //Process each value from the KnowledgeGraphRow array
    public void ProcessKnowledgeGraphRowValue(object value)
    {
      switch (value)
      {
        //Graph value?
        case KnowledgeGraphValue kg_val:
          var kg_type = kg_val.KnowledgeGraphValueType.ToString();
          System.Diagnostics.Debug.WriteLine(
            $"KnowledgeGraphValue: '{kg_type}'");
          ProcessGraphValue(kg_val);//Recurse
          return;
        //Primitive types...add additional logic as needed
        case System.DBNull dbn:
          System.Diagnostics.Debug.WriteLine("DBNull.Value");
          return;
        case string str:
          System.Diagnostics.Debug.WriteLine($"'{str}' (string)");
          return;
        case long l_val:
          System.Diagnostics.Debug.WriteLine($"{l_val} (long)");
          return;
        case int i_val:
          System.Diagnostics.Debug.WriteLine($"{i_val} (int)");
          return;
        case short s_val:
          System.Diagnostics.Debug.WriteLine($"{s_val} (short)");
          return;
        case double d_val:
          System.Diagnostics.Debug.WriteLine($"{d_val} (double)");
          return;
        case float f_val:
          System.Diagnostics.Debug.WriteLine($"{f_val} (float)");
          return;
        case DateTime dt_val:
          System.Diagnostics.Debug.WriteLine($"{dt_val} (DateTime)");
          return;
        case DateOnly dt_only_val:
          System.Diagnostics.Debug.WriteLine($"{dt_only_val} (DateOnly)");
          return;
        case TimeOnly tm_only_val:
          System.Diagnostics.Debug.WriteLine($"{tm_only_val} (TimeOnly)");
          return;
        case DateTimeOffset dt_tm_offset_val:
          System.Diagnostics.Debug.WriteLine(
            $"{dt_tm_offset_val} (DateTimeOffset)");
          return;
        case System.Guid guid_val:
          var guid_string = guid_val.ToString("B");
          System.Diagnostics.Debug.WriteLine($"'{guid_string}' (Guid)");
          return;
        case Geometry geom_val:
          var geom_type = geom_val.GeometryType.ToString();
          var is_empty = geom_val.IsEmpty;
          var wkid = geom_val.SpatialReference?.Wkid ?? 0;
          System.Diagnostics.Debug.WriteLine(
            $"geometry: {geom_type}, empty: {is_empty}, sr_wkid {wkid} (shape)");
          return;
        default:
          //Blob? Others?
          var type_str = value.GetType().ToString();
          System.Diagnostics.Debug.WriteLine($"Primitive: {type_str}");
          return;
      }
    }
    
    // ...submit query or search
    //using (var kg_rc = kg.SubmitQuery(kg_qf)) {
    //using (var kg_rc = kg.SubmitSearch(kg_sf)) {
    //  ...wait for rows ...
    //  while (await kg_rc.WaitForRowsAsync()) {
    //   ...rows have been retrieved
    //   while (kg_rc.MoveNext()) {
    //     ...get the current KnowledgeGraphRow
    //     using (var graph_row = kg_rc.Current) {
    //        var val_count = (int)graph_row.GetCount();
    //        for (int i = 0; i<val_count; i++)
    //           ProcessKnowledgeGraphRowValue(graph_row[i]);
    
    Requirements

    Target Platforms: Windows 11, Windows 10

    ArcGIS Pro version: 3.2 or higher.
    See Also