Updating attributes of existing features

In this topic

• Attribute updates
• Updating attributes with subtypes
• Updating attributes of a set of features
  • Working with cursors
  • Working with edit selections
• Validating feature attributes
• Updating attributes outside edit sessions
• Updating attributes using SQL

Attribute updates

m_Editor.StartOperation();
feature.Value(feature.Fields.FindField("LotNumberField"))=m_lotNum;
feature.Value(4)=92373;
feature.Store();
m_Editor.StopOperation("Attribute update");

m_Editor.StartOperation()
feature.Value(feature.Fields.FindField("LotNumberField"))=m_lotNum
feature.Value(4)=92373
feature.Store()
m_Editor.StopOperation("Attribute update")

Updating attributes with subtypes

IRowSubtypes rowSubtypes=feature as IRowSubtypes;
if (rowSubtypes != null)
{
    // Set the subtype.
    rowSubtypes.SubtypeCode=IEditLayers.CurrentSubtype; //or a valid subtype code
    // Initialize default values for the subtype.
    rowSubtypes.InitDefaultValues();
    feature.Store();
}

Dim rowSubtypes As IRowSubtypes=feature
If Not rowSubtypes Is Nothing Then
    'Set the subtype.
    rowSubtypes.SubtypeCode=IEditLayers.CurrentSubtype 'or a valid subtype code
    'Initialize default values for the subtype.
    rowSubtypes.InitDefaultValues()
    feature.Store()
End If

Updating attributes of a set of features

Working with cursors

m_editor.StartOperation();
//Loop through midpoints, select polygon, and calculate.
for (int i=0; i < midPoints.PointCount; i++)
{
    IPoint midPoint=midPoints.get_Point(i);
    spatialFilter=new SpatialFilterClass();
    spatialFilter.Geometry=midPoint;
    spatialFilter.GeometryField =
        m_editLayers.CurrentLayer.FeatureClass.ShapeFieldName;
    spatialFilter.SpatialRel=esriSpatialRelEnum.esriSpatialRelWithin;
    SearchCursor=featLayer.Search(spatialFilter, true);
    while ((feature=SearchCursor.NextFeature()) != null)
    {
        feature.set_Value(feature.Fields.FindField(cmbPINField.Text), m_lotNum);
        feature.Store();
        m_lotNum += int.Parse(txtlotinc.Text);
    }
}

m_editor.StopOperation("Polygon Update");

m_editor.StartOperation()
'Loop through midpoints, select polygon, and calculate.
For i As Integer=0 To midPoints.PointCount - 1
    Dim midPoint As IPoint=midPoints.Point(i)
    spatialFilter=New SpatialFilterClass()
    spatialFilter.Geometry=midPoint
    spatialFilter.GeometryField=m_editLayers.CurrentLayer.FeatureClass.ShapeFieldName
    spatialFilter.SpatialRel=esriSpatialRelEnum.esriSpatialRelWithin
    SearchCursor=featLayer.Search(spatialFilter, True)
    feature=SearchCursor.NextFeature()
    Do While feature IsNot Nothing
        feature.Value(feature.Fields.FindField(cmbPINField.Text))=m_lotNum
        feature.Store()
        m_lotNum +=Integer.Parse(txtlotinc.Text)
        feature=SearchCursor.NextFeature()
    Loop
Next i
m_editor.StopOperation("Polygon Update")

public void UseUpdateCursor(IFeatureClass featureClass)
{
    // Restrict the number of features to be updated.
    IQueryFilter queryFilter=new QueryFilterClass();
    queryFilter.WhereClause="NAME='Highway 104'";
    queryFilter.SubFields="TYPE";

    // Use IFeatureClass.Update to populate IFeatureCursor.
    IFeatureCursor updateCursor=featureClass.Update(queryFilter, false);

    int typeFieldIndex=featureClass.FindField("TYPE");
    IFeature feature=null;
    try
    {
        while ((feature=updateCursor.NextFeature()) != null)
        {
            feature.set_Value(typeFieldIndex, "Toll Highway");
            updateCursor.UpdateFeature(feature);
        }
    }
    catch (COMException comExc)
    {
        // Handle any errors that might occur on NextFeature().
    }

    // If the cursor is no longer needed, release it.
    Marshal.ReleaseComObject(updateCursor);
}

Public Sub UseUpdateCursor(ByVal featureClass As IFeatureClass)
    
    ' Restrict the number of features to be updated.
    Dim queryFilter As IQueryFilter=New QueryFilterClass()
    queryFilter.WhereClause="NAME='Highway 104'"
    queryFilter.SubFields="TYPE"
    
    ' Use IFeatureClass.Update to populate IFeatureCursor.
    Dim updateCursor As IFeatureCursor=featureClass.Update(queryFilter, False)
    Dim typeFieldIndex As Integer=featureClass.FindField("TYPE")
    
    Try
    Dim feature As IFeature=updateCursor.NextFeature()
    Do While Not feature Is Nothing
        feature.Value(typeFieldIndex)="Toll Highway"
        updateCursor.UpdateFeature(feature)
        feature=updateCursor.NextFeature()
    Loop
    Catch comExc As COMException
    ' Handle any errors that might occur on NextFeature().
    End Try
    
    ' If the cursor is no longer needed, release it.
    Marshal.ReleaseComObject(updateCursor)
    
End Sub

Working with edit selections

Validating feature attributes

Updating attributes outside edit sessions

public void EditsOutsideAnEditSession(IWorkspace workspace)
{
    // Cast the workspace to the IWorkspaceEdit2 interface to confirm whether the workspace
    // is in an edit operation. If so, raise an exception.
    IWorkspaceEdit2 workspaceEdit2=(IWorkspaceEdit2)workspace;
    if (workspaceEdit2.IsInEditOperation)
    {
        throw new Exception("Cannot use ITransactions during an edit operation.");
    }
    // Begin a transaction.
    ITransactions transactions=(ITransactions)workspace;
    transactions.StartTransaction();
    try
    {
        // Perform updates and inserts here.
        // If the updates and inserts are successful, commit the changes.
        transactions.CommitTransaction();
    }
    catch (COMException comExc)
    {
        // If an error occurs during the inserts and updates, rollback the transaction.
        transactions.AbortTransaction();
    }
}

Public Sub EditsOutsideAnEditSession(ByVal workspace As IWorkspace)
    ' Cast the workspace to the IWorkspaceEdit2 interface to confirm whether the workspace
    ' is in an edit operation. If so, raise an exception.
    Dim workspaceEdit2 As IWorkspaceEdit2=CType(workspace, IWorkspaceEdit2)
    If workspaceEdit2.IsInEditOperation Then
        Throw New Exception("Cannot use ITransactions during an edit operation.")
    End If
    
    ' Begin a transaction.
    Dim transactions As ITransactions=CType(workspace, ITransactions)
    transactions.StartTransaction()
    Try
    ' Perform updates and inserts here.
    
    ' If the updates and inserts are successful, commit the changes.
    transactions.CommitTransaction()
    Catch comExc As COMException
    ' If an error occurs during the inserts and updates, rollback the transaction.
    transactions.AbortTransaction()
    End Try
End Sub

Updating attributes using SQL

• Avoid updating records using SQL after the data has been versioned, unless SQL is used in conjunction with an ArcSDE multiversioned view. This applies to ArcSDE geodatabases only - personal geodatabases do not support versioning.
• Always issue a commit or rollback statement after the SQL statement has been executed in the database to ensure the changes are either made permanent or undone as required. Failing to do so can cause problems for the database management system (DBMS). For example, a database compress operation will wait for uncommitted DBMS DML statements to be committed before executing successfully.
• When updating unversioned data using SQL, avoid modifying any attributes that, through geodatabase behavior, affect other objects in the database - as in the case of feature-linked annotation and relationship classes.
• Avoid using SQL to modify the geometries of feature classes that participate in any advanced geodatabase objects or functionality such as geometric networks, topologies, and relationships. Modifications to feature classes participating in networks, topologies, annotation, dimension, or relationship classes should be restricted to ArcGIS for Desktop applications and the geodatabase API. Third party SQL-based applications can read the data, but any modifications they make to the data will not be reflected in the network, topology, or relationship.
• Never update the Row_ID (ObjectID) field with SQL - this field is allocated and managed by the geodatabase and should not be altered.