Get the value of an attribute in C#

[Anonymous]

Hi,

I'm trying to read the value out of an attribute called "REV" in a title block called "STAR2" in C#. I then want to assign the value as the definition in my dictionary shown below, and return that to the method that eventually will call this one.

Please see a snippet of my code, the places in bold are the areas I [think I] need to address:

        // Gets the attributes from the drawing
        public getDWGInfo()
        {
            // Declarations
            int dwgCount = 0;

            DocumentCollection docs = Application.DocumentManager;
            var dwgDict = new Dictionary<string, string>();

            foreach (Document doc in docs)
            {
                Database acCurDb;
                acCurDb = Application.DocumentManager.MdiActiveDocument.Database;

                using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
                {
                    // Open the block table for read
                    BlockTable acBlkTbl;
                    acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, OpenMode.ForRead) as BlockTable;

                    if (acBlkTbl.Has("STAR2"))
                    {
                        // ##### Get the value of attribute "REV" from "STAR2" & Add to dictionary below?
                        dwgDict[doc.Name] = ;
                        dwgCount++;
                    }
                    else
                    {
                        Application.ShowAlertDialog("The drawing does not have a STAR2 titleblock with a REV attribute, couldn't add to list.");
                    }
                }
            }
            // ##### Return dwgDict to the method that called it?
        }

Could you toss me some bones

[_gile]

Hi,

Are you looking for the (default) value of an attribute definition (AttributeDefinition) contained in a block definition (BlockTableRecord) in the block table (BlockTable) or the value of an attribute reference (AttributeReference) bound to a block reference (BlockReference) inserted in a the model space or paper space of the drawing?

[Anonymous]

I think I’m looking for an AttributeReference bound to a BlockReference

Each drawing has a block called STAR2 which has an attribute REV, I’m trying to pull the value assigned to the tag REV & add that to a dictionary as a value (attribute) for the key (drawing name)

[_gile · Accepted solution]

You can try something like this:

        public static Dictionary<string, string> GetAttribs(string blockName, string tag)
        {
            // create a new instance of Dictionary<string, string>
            var attribs = new Dictionary<string, string>();

            // get the documents collection
            var docs = Application.DocumentManager;

            // use an OpenCloseTransaction which is not related to a document or database
            using (var tr = new OpenCloseTransaction())
            {
                // iterate through the documents
                foreach (Document doc in docs)
                {
                    // get the document database
                    var db = doc.Database;

                    // get the database block table
                    var bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);

                    // if the block table contains a block definitions named 'blockName'...
                    if (bt.Has(blockName))
                    {
                        // open the block definition
                        var btr = (BlockTableRecord)tr.GetObject(bt[blockName], OpenMode.ForRead);

                        // get the inserted block references ObjectIds
                        var ids = btr.GetBlockReferenceIds(true, true);

                        // if any...
                        if (0 < ids.Count)
                        {
                            // open the first block reference
                            var br = (BlockReference)tr.GetObject(ids[0], OpenMode.ForRead);

                            // iterate through the attribute collection
                            foreach (ObjectId id in br.AttributeCollection)
                            {
                                // open the attribute reference
                                var attRef = (AttributeReference)tr.GetObject(id, OpenMode.ForRead);

                                // if the attribute tag is equal to 'tag'
                                if (attRef.Tag.Equals(tag, StringComparison.CurrentCultureIgnoreCase))
                                {
                                    // add an entry to the dictionary
                                    attribs[doc.Name] = attRef.TextString;
                                    // break the loop
                                    break;
                                }
                            }
                        }
                    }
                }
            }
            // return the dictionary
            return attribs;
        }

[Anonymous]

Thank you gile.

I want to call this method once, then have the returned dictionary "attribs" be globally accessible to anything in the same namespace for use in my Forms interface which is in another class file.

How can this be accomplished?

[_gile]

It's difficult to reply without knowing your projetc architecture.

Typically, to expose data from a class to other classes, you can use instance or static  properties.

You can also pass the data to an overload constructor of the Form (as explain in the 'Modal dialog box' part of this tutorial).

Anyway, you should learn the .NET basics outside of AutoCAD until you're comfortable with OOP, .NET Framework, Visual Studio and C# before trying to use the AutoCAD .NET API.