What’s the best way to iterate through an entire Database?

By Philippe Leefsma

The objects stored in the database get an handle value that gets incremented sequentially, so the fastest approach if one wants to iterate through the whole content of a Database, is to start from handle = 1 to the max handle existing in the Database. P/Invoking "acdbHandEnt" can then help to retrieve the ObjectId from an handle.

The following C# code illustrates how to do that:

public struct ads_name

{

    public IntPtr a;

    public IntPtr b;

};

 

[DllImport("acdb19.dll",

CharSet = CharSet.Unicode,

CallingConvention = CallingConvention.Cdecl,

EntryPoint = "acdbHandEnt")]

public static extern int acdbHandEnt(

    string handle, ref ads_name name);

 

[CommandMethod("IterateDb")]

static public void IterateDb()

{

    ads_name ename = new ads_name();

 

    Document doc = Application.DocumentManager.MdiActiveDocument;

    Database db = doc.Database;

    Editor ed = doc.Editor;

 

    ObjectIdCollection validIds = new ObjectIdCollection();

 

    // now get the last handle in the db

    Handle handseed = db.Handseed;

 

    // copy the handseed total into an efficient raw datatype

    long handseedTotal = handseed.Value;

 

    // loop from 0 to the last handle (this could be a big loop)

    for (long i = 1; i < handseedTotal; ++i)

    {

        string handle = Convert.ToString(i, 16);

 

        // get the ename by converting

        // the long to a hex value string

        int res = acdbHandEnt(handle, ref ename);

 

        if (res != 5100) // RTNORM

            continue;

 

        // convert the ename to an objectid

        ObjectId id = new ObjectId(ename.a);

 

        // check if it’s a valid objectId

        if (!id.IsValid)

            continue;

 

        try

        {

            // open if not erased

            using (DBObject obj =

                id.Open(OpenMode.ForRead, false))

            {

                validIds.Add(id);

            }

        }

        catch

        {

 

        }

    }

 

    ed.WriteMessage("\nNumber of retrieved valid ObjectIds: "

        + validIds.Count.ToString());

 

    validIds.Clear();

}

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