Adding field to attribute value of a block inserted to modelspace

<?xml encoding=”UTF-8″>By Deepak Nadig

Here is a blog by Stephen Preston which explains inserting a block with attributes.

Below is a C# code to insert a field to the attribute value of a block. Create a drawing with a block named “test” containing a circle having an
attribute definition(tag to be assigned) to test the code.

[CommandMethod("addFieldToAttribute")]
public void addFieldToAttribute()
{
Database db = Application.DocumentManager.MdiActiveDocument.Database;
Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
string blkName = "test";
using (Transaction acTrans = db.TransactionManager.StartTransaction())
{
BlockTable blkTbl = db.BlockTableId.GetObject(OpenMode.ForRead) as BlockTable;
if (blkTbl.Has(blkName))
{
BlockTableRecord blkTblRec = blkTbl[blkName].GetObject(OpenMode.ForRead)
as BlockTableRecord;
using (BlockReference blkRef = new BlockReference(Point3d.Origin, blkTblRec.ObjectId))
{
BlockTableRecord ms = blkTbl[BlockTableRecord.ModelSpace].GetObject(OpenMode.ForWrite)
as BlockTableRecord;
ms.AppendEntity(blkRef);
acTrans.AddNewlyCreatedDBObject(blkRef, true);
if (blkTblRec.HasAttributeDefinitions)
{
Point3d cp = new Point3d(0, 0, 0);
Circle circ = new Circle();
ObjectId objID = new ObjectId();
foreach (ObjectId id in blkTblRec)
{
DBObject obj = id.GetObject(OpenMode.ForRead);
if ((obj) is Circle)
{
circ = (Circle)obj; // get the circle object
cp = circ.Center;
objID = circ.ObjectId;
}
if (obj is AttributeDefinition)
{
AttributeDefinition acAttDef = (AttributeDefinition)obj;
//Create a new AttributeReference
using (AttributeReference acAttRef = new AttributeReference())
{
acAttRef.SetAttributeFromBlock(acAttDef, blkRef.BlockTransform);
acAttRef.Position = acAttDef.Position.TransformBy(blkRef.BlockTransform);
acAttRef.TextString = acAttDef.TextString;
acAttRef.Tag = acAttDef.Tag;
//Add the AttributeReference to the BlockReference
blkRef.AttributeCollection.AppendAttribute(acAttRef);
//Assign the centerpoint of the circle to a field code string
string str1 = "%<\AcObjProp.16.2 Object(%<\_ObjId ";
string strID = objID.OldIdPtr.ToString();
string str2 = ">%,1).Center \f "%lu2">%";
string str = str1 + strID + str2;
string fldstr = string.Format(str, cp.ToString());
//crete a new field with field code parameter
Field field = new Field(fldstr);
field.Evaluate();
FieldEvaluationStatusResult fieldEval = field.EvaluationStatus;
if (fieldEval.Status != FieldEvaluationStatus.Success)
{
acTrans.Abort();
ed.WriteMessage(string.Format("FieldEvaluationStatus Message: {0} - {1}",
fieldEval.Status, fieldEval.ErrorMessage));
return;
}
else
{
try
{   //set the field to attribute reference
acAttRef.SetField(field);
acTrans.AddNewlyCreatedDBObject(field, true);
ed.WriteMessage(string.Format("Field value ({1}) is inseterd to Attribute '{0}' of the Block '{2}' ",
acAttRef.Tag, field.Value, blkRef.Name));
}
catch
{
field.Dispose();
ed.WriteMessage(string.Format("Failed to set attribute field '{0}' - {1}",
acAttRef.Tag, acAttRef.Handle));
}
}
acTrans.AddNewlyCreatedDBObject(acAttRef, true);
}
}
}
}
}
}
acTrans.Commit();
}
}