Topic: Select Entity By Handle

[cadpro]

Hi,

How do I select an entity if I know the handle of that entity as string?

Thanks

[gile]

Hi,

If your handle is a Handle object, you can use:

Code: [Select]

ObjectId id = Database.GetObjectId(false, handle, 0);If your handle is a string convert the string into a long to create a new Handle object, then get the ObjectId:

Code: [Select]

long lg = Convert.ToInt64(handle, 16);
ObjectId id = Database.GetObjectId(false, new Handle(lg), 0)
EDIT: two safer methods

Code: [Select]

public ObjectId HandleToObjectId(string str, Database db)
{
long id;
if (Int64.TryParse(str, System.Globalization.NumberStyles.HexNumber, null, out id))
return HandleToObjectId(new Handle(id), db);
else
return ObjectId.Null;
}

public ObjectId HandleToObjectId(Handle handle, Database db)
{
try { return db.GetObjectId(false, handle, 0); }
catch { return ObjectId.Null; }
}

[kaefer]

Code: [Select]

...
public ObjectId HandleToObjectId(Handle handle, Database db)
{
try { return db.GetObjectId(false, handle, 0); }
catch { return ObjectId.Null; }
}

Hi gile,

much better, but still... there's TryGetObjectId too. I didn't know that you could pass null instead of InvariantCulture. And if you were so inclined, you could use Nullables to signal the error condition. Something like:

Code: [Select]

    static class TryGetObjectIdDemo
    {
        public static ObjectId? StringToObjectId(this Database db, string str)
        {
            long hnd;
            ObjectId objId;
            if(!Int64.TryParse(str, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out hnd))
                return null;
            if(!db.TryGetObjectId(new Handle(hnd), out objId))
                return null;
            return objId;
        }
    }


[gile]

Hi Thorsten,

I didn't know (and can't find in the docs) any Database.TryGetObjectId() method.
Isn't it from your own library ?

[Kerry]

public bool TryGetObjectId(Handle objHandle, out ObjectId id);
 
Declaring Type: Autodesk.AutoCAD.DatabaseServices.Database
Assembly: Acdbmgd, Version=18.2.0.0

[kaefer]

I didn't know (and can't find in the docs) any Database.TryGetObjectId() method.

Amazing, those docs. It wasn't in 16.2, but I saw Andrey using it; it must have been added in any release between 2007 and 2009.

[gile]

Thanks Kerry,

It seems it have been added to the 2012 (18.2) version I don't see it in the 2011 Object Browser.

[cadpro]

Thanks all for your help. I basically wanted to highlight the selected entity. So this is what I did with gile's code as reference.

Code: [Select]


           Using tr As Transaction = db.TransactionManager.StartTransaction()
                Dim ln As Long = Convert.ToInt64(handle, 16)
                Dim oId As ObjectId = db.GetObjectId(False, New Handle(ln), 0)
                Dim ent As Entity = CType(tr.GetObject(oId, OpenMode.ForRead), Entity)
                If Not ent Is Nothing Then
                    ent.Highlight()
                End If
            End Using


Thanks