Arc: Editing Data

1
Arc Editing Data

• Dr Andy Evans

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Editing Data

• Putting Arc into an editing session.
• Adding a new field/column.
• Changing a value.

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Editing sessions

• Although some cursors can be used directly in
  some circumstances to edit data, it is usually
  worth opening an editing session
  programmatically.
• To do this, we need the workspace.

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Workspaces

• Open a workspace (casts/try-catches removed
  throughout)
• IWorkspaceFactory wsF new DataSourcesGDB.FileGD
  BWorkspaceFactoryClass()
• IWorkspace ws wsF.OpenFromFile(geodatabasePath,
  0)
• Find current (note difficulties with proxy
  classes)
• IFeatureDatasetProxy ifdp iGeoFeaturelayer.getF
  eatureClass().
• getFeatureDataset()
• IWorkspaceProxy iwp ifdp.getWorkspace()
• IWorkspaceFactory wf iwp.getWorkspaceFactory()
• IWorkspace ws wf.openFromFile
• (iwp.getPathName(), 0)

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Workspaces

• Make one
• IWorkspaceName wsn workspaceFactory.create
• ("c\temp","tempGDB",null,0)
• IName name wsn
• IWorkspace iWorkspace name.open()
• Once we have an iWorkspace, cast to
  IWorkspaceEdit
• IWorkspaceEdit iwe (IWorkspaceEdit) iWorkspace

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Editing sessions

• iwe.startEditing(true) Opens a session
• iwe.startEditOperation() Starts a group of
  edits
• iwe.stopEditOperation() Ends a group of edits
• iwe.stopEditing(true) Closes session
• You can do multiple edit operations within a
  session. They are only needed for operations on
  features that are part of a Topology or Geometric
  Network, but are good practice.

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Editing Data

• Putting Arc into an editing session.
• Adding a new field/column.
• Changing a field.
• Adding a field
• First make a new Field.
• Then set it up.
• Then add it.

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Making a field/column

• IField field new Field() Note rare
  making of a new object
• Note that the IField label is used to make the
  object, but we need an IFieldEdit view on it to
  edit things like the name.
• IFieldEdit fieldEdit field
• fieldEdit.setName("Population")
• fieldEdit.setType
• (esriFieldType.esriFieldTypeInteger)
• http//help.arcgis.com/en/sdk/10.0/Java_AO_ADF/api
  /arcobjects/com/esri/arcgis/geodatabase/esriFieldT
  ype.html

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Adding a Field

• Get a FeatureClass from the IFeatureLayer
• IFeatureClass fClass featurelayer.getFeatureC
  lass()
• Add the field to the existing fields.
• IFields fields fClass.getFields()
• fClass.addField(field)
• Might want to check the field doesnt exist with
  fClass.findField("columnName") first (returns -1
  when none found).

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Editing data

• Use a cursor to find the features to edit.
• Get a feature.
• Edit its value for a specific column.
• Tell the cursor to store the changes back into
  the original database.
• Release the cursor resources.

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Editing Data

• Data is set using a FeatureCursor to get the
  feature
• IFeatureCursor fCursor null
• Three types
• fCursor fClass.IFeatureClass_update(null,false)
  
• fCursor fClass.IFeatureClass_insert(false)
• fCursor fClass.search(null, false)
• IFeature feature pFCursor.nextFeature()
• Cursors also have methods for adding and deleting
  rows.

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Cursors

• Recycling cursors can reuse resources allocated
  to a row. We dont want this, as these
  temporarily store changes we want.
• Therefore, we need to use non-recycling cursors
• fCursor fClass.IFeatureClass_insert(false)
• It also means we must be extra-careful to release
  resources at the end of editing. To do this we
  use the ESRI Cleaner class after weve finished
  with the cursor/editing
• Cleaner.release(cursor)

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Change the value

• feature.setValue(columnIndex, Object)
• To change a spatial location you set the shape
• IPoint point new Point()
• point.setX(300000.0)
• point.setY(799000.0)
• feature.setValue(shapeColumnIndex,point)
• Or, better
• feature.setShapeByRef(point)

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Shapes

• Implement com.esri.arcgis.geometry IGeometry.
• Include
• Line / Polyline
• Polygon / MultiPatch
• Point / Multipoint

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Fix the value

• For an Update/Insert Cursor
• fCursor.updateFeature(feature)
• For a Search Cursor
• feature.store()
• Note the different objects the methods are in.
• Note also that because IFeatures actually inherit
  from IRow, similar things can be done to table
  rows. See IFeatureClass docs for info.
• Note that under some circumstances editing using
  Update and Insert cursors is possible outside of
  an editing session, but isnt advised.

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Summary Editing

• Open an edit session.
• Open an edit operation.
• Get a cursor of features to edit.
• Edit the features.
• Tell the cursor to fix the changes.
• Free up cursor resources.
• Close the edit operation.
• Close the edit session.