ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Core.Data.DDL Namespace / SchemaBuilder Class / Modify Method / Modify(FeatureClassDescription) Method
Indicates the ArcGIS.Core.Data.FeatureClass to be modified.
Example Version

Modify(FeatureClassDescription) Method
Enqueue the modify operation on the object referred to by the FeatureClassDescription. This method must be called on the MCT. Use QueuedTask.Run.
Syntax

Parameters

featureClassDescription
Indicates the ArcGIS.Core.Data.FeatureClass to be modified.
Exceptions
ExceptionDescription
featureClassDescription is null.
This method or property must be called within the lambda passed to QueuedTask.Run.
Example
Adding fields to a FeatureClass
public void AddFieldsInFeatureClassSnippet(Geodatabase geodatabase)
{
    // Adding following fields to the 'Parcels' FeatureClass
    // Global ID
    // Parcel_ID
    // Tax_Code
    // Parcel_Address

    // The FeatureClass to add fields
    string featureClassName = "Parcels";

    FeatureClassDefinition originalFeatureClassDefinition = geodatabase.GetDefinition<FeatureClassDefinition>(featureClassName);
    FeatureClassDescription originalFeatureClassDescription = new FeatureClassDescription(originalFeatureClassDefinition);

    // The four new fields to add on the 'Parcels' FeatureClass
    FieldDescription globalIdField = FieldDescription.CreateGlobalIDField();
    FieldDescription parcelIdDescription = new FieldDescription("Parcel_ID", FieldType.GUID);
    FieldDescription taxCodeDescription = FieldDescription.CreateIntegerField("Tax_Code");
    FieldDescription addressDescription = FieldDescription.CreateStringField("Parcel_Address", 150);

    List<FieldDescription> fieldsToAdd = new List<FieldDescription> { globalIdField, parcelIdDescription,
taxCodeDescription, addressDescription };

    // Add new fields on the new FieldDescription list
    List<FieldDescription> modifiedFieldDescriptions = new List<FieldDescription>(originalFeatureClassDescription.FieldDescriptions);
    modifiedFieldDescriptions.AddRange(fieldsToAdd);

    // The new FeatureClassDescription with additional fields
    FeatureClassDescription modifiedFeatureClassDescription = new FeatureClassDescription(originalFeatureClassDescription.Name,
      modifiedFieldDescriptions, originalFeatureClassDescription.ShapeDescription);

    SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

    // Update the 'Parcels' FeatureClass with newly added fields
    schemaBuilder.Modify(modifiedFeatureClassDescription);
    bool modifyStatus = schemaBuilder.Build();

    if (!modifyStatus)
    {
        IReadOnlyList<string> errors = schemaBuilder.ErrorMessages;
    }
}
Create Domain and Field Definition on KG Schemas with SchemaBuilder
    await QueuedTask.Run(() =>
    {
      using (var kg = GetKnowledgeGraph())
      {
        if (kg == null)
          return;

        var entity_name = "Fruit";

        //Domains are managed on the GDB objects...
        var fruit_fc = kg.OpenDataset<FeatureClass>(entity_name);
        var fruit_fc_def = fruit_fc.GetDefinition();

        var fieldFruitTypes = fruit_fc_def.GetFields()
              .FirstOrDefault(f => f.Name == "FruitTypes");
        var fieldShelfLife = fruit_fc_def.GetFields()
            .FirstOrDefault(f => f.Name == "ShelfLife");

        //Create a coded value domain and add it to a new field
        var fruit_cvd_desc = new CodedValueDomainDescription(
          "FruitTypes", FieldType.String, 
          new SortedList<object, string> {
                          { "A", "Apple" },
                          { "B", "Banana" },
                          { "C", "Coconut" }
          })  {
            SplitPolicy = SplitPolicy.Duplicate,
            MergePolicy = MergePolicy.DefaultValue
        };

        //Create a Range Domain and add the domain to a new field description also
        var shelf_life_rd_desc = new RangeDomainDescription(
                                      "ShelfLife", FieldType.Integer, 0, 14);

        var sb = new SchemaBuilder(kg);
        sb.Create(fruit_cvd_desc);
        sb.Create(shelf_life_rd_desc);

        //Create the new field descriptions that will be associated with the
        //"new" FruitTypes coded value domain and the ShelfLife range domain
        var fruit_types_fld = new ArcGIS.Core.Data.DDL.FieldDescription(
                                      "FruitTypes", FieldType.String);
        fruit_types_fld.SetDomainDescription(fruit_cvd_desc);

        //ShelfLife will use the range domain
        var shelf_life_fld = new ArcGIS.Core.Data.DDL.FieldDescription(
"ShelfLife", FieldType.Integer);
        shelf_life_fld.SetDomainDescription(shelf_life_rd_desc);

        //Add the descriptions to the list of field descriptions for the
        //fruit feature class - Modify schema needs _all_ fields to be included
        //in the schema, not just the new ones to be added.
        var fruit_fc_desc = new FeatureClassDescription(fruit_fc_def);

        var modified_fld_descs = new List<ArcGIS.Core.Data.DDL.FieldDescription>(
          fruit_fc_desc.FieldDescriptions);

        modified_fld_descs.Add(fruit_types_fld);
        modified_fld_descs.Add(shelf_life_fld);

        //Create a feature class description to modify the fruit entity
        //with the new fields and their associated domains
        var updated_fruit_fc =
          new FeatureClassDescription(entity_name, modified_fld_descs,
                                      fruit_fc_desc.ShapeDescription);

        //Add the modified fruit fc desc to the schema builder
        sb.Modify(updated_fruit_fc);

        //Run the schema builder
        try
        {
          if (!kg.ApplySchemaEdits(sb))
          {
            var err_msg = string.Join(",", sb.ErrorMessages.ToArray());
            System.Diagnostics.Debug.WriteLine($"Create domains error: {err_msg}");
          }
        }
        catch (Exception ex)
        {
          System.Diagnostics.Debug.WriteLine(ex.ToString());
        }
      }
    });
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.
See Also