c# code to add new attribute value to a block

[Anonymous]

I wanted to add new attribute value to block by opening a autocad drawing & selecting block for which the new attribute value should be added

[_gile]

Hi,

In view of all your recent posts, could you elaborate about the context in which you wish to do this (in-process vs out-of-process)?

[Anonymous]

I want to open a autocad drawing and select the block & in the program I want a textbox & a button the value given the user in the textbox should be added to the selected block by clicking on the button

[_gile]

Sorry, but it's still not clear to me.
Do you want to create a custom AutoCAD command or, again, do that from a standalone executable, which is a completely different (and not so easy) process?
Is the block selected by the user a particular block? If so, is it dynamic? What's its name? Does it contain one or more attributes?
Is it to add an attribute or modify the value of an existing attribute? In any case, what is the label of the attribute?

And, if possible, show what you have done so far.

[Anonymous]

imagine I have a autocad drawing it contains "n" number of block & each block has many attributes but now the user wants to add a new attribute value for a particular block which he wants to be added so he has to select the block first & then add the new attribute to that block

[_gile]

Do you want to only add an attribute reference to the selected block reference or add an attribute definition to the block definition and then synchronize all the references?

[Anonymous]

I would like to add an attribute reference to the selected block reference. 

[_gile]

You certainly know that this kind of attribute reference will be erased if the ATTSYNC command is run for this block.

Here's an example of AutoCAD plugin (i.e., a class library DLL which have to be netloaded in AutoCAD) containg custom command which shows a little dialog box to let the user enter the attribute value, then it prompts the user to select a block reference and specify the attribute insertion point.

using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Runtime;

namespace AmazingRequestSample
{
    public class Commands
    {
        [CommandMethod("ADDATTREF")]
        public static void AddAttributeReference()
        {
            var doc = Application.DocumentManager.MdiActiveDocument;
            var db = doc.Database;
            var ed = doc.Editor;

            // display a dialog box to get the attribute value
            string attValue;
            using (var dialog = new AttributeValueDialog())
            {
                if (Application.ShowModalDialog(dialog) != System.Windows.Forms.DialogResult.OK)
                    return;
                attValue = dialog.AttributeValue;
            }

            // prompts the user to select a block reference
            var peo = new PromptEntityOptions("\nSelect block reference: ");
            peo.SetRejectMessage("\nSelected object is not a block reference.");
            peo.AddAllowedClass(typeof(BlockReference), true);
            var per = ed.GetEntity(peo);
            if (per.Status != PromptStatus.OK)
                return;

            // prompts the user to specify the attribute insertion point
            var ppr = ed.GetPoint("\nSpecify the attribute insertion point: ");
            if (ppr.Status != PromptStatus.OK)
                return;
            var insPoint = ppr.Value.TransformBy(ed.CurrentUserCoordinateSystem);

            // create the attribute reference and add it to the attribute collection of the selected block
            using (var tr = db.TransactionManager.StartTransaction())
            {
                var br = (BlockReference)tr.GetObject(per.ObjectId, OpenMode.ForWrite);
                var attRef = new AttributeReference(insPoint, attValue, "TAG", db.Textstyle)
                { LockPositionInBlock = false };
                br.AttributeCollection.AppendAttribute(attRef);
                tr.AddNewlyCreatedDBObject(attRef, true);
                tr.Commit();
            }
        }
    }
}

The dialog box

using System.Windows.Forms;

namespace AmazingRequestSample
{
    public partial class AttributeValueDialog : Form
    {
        public AttributeValueDialog()
        {
            InitializeComponent();
            AcceptButton = buttonOk;
            CancelButton = buttonCancel;
            buttonOk.DialogResult = DialogResult.OK;
            buttonCancel.DialogResult = DialogResult.Cancel;
        }

        public string AttributeValue => textBoxAttValue.Text;
    }
}

[Anonymous]

Thank you so much for ur quick response

[Anonymous]

I'm getting error in the below line

var attRef = new AttributeReference(insPoint, attValue, "TAG", db.Textstyle) { LockPositionInBlock = false };

Use of unassigned local variable "attValue" but i have assigned the variable

[_gile]

I do not have such error.

Is it an error at edition time (which prevent the compilation in Visual Studio) or an exception thrown at running time?

[Anonymous]

It is an error at edition time

[_gile]

Your project should contains 2 classes:

• Commands.cs where the command is defined
• AttributeValueDialog.cs the dialog box decription

[Anonymous]

Even I have done the same thing. But I m getting a error

[_gile]

You didn't correctly the code i posted.

Replace:

            string attValue;
            using (var dialog = new AttributeValueDialog())
            {
                if (Application.ShowModalDialog(dialog) != System.Windows.Forms.DialogResult.OK)
                    attValue = dialog.AttributeValue;
            }

with:

            string attValue;
            using (var dialog = new AttributeValueDialog())
            {
                if (Application.ShowModalDialog(dialog) != System.Windows.Forms.DialogResult.OK)
                    return;
                attValue = dialog.AttributeValue;
            }

[Anonymous]

Ya I m sorry. Thank you for correcting me

[Anonymous]

Thank you sooo much it worked successfully

Now I want an enhancement in that code. I want to add the attribute value by selecting multiple blocks how can we do that??

[_gile]

You can use a selection set got with Editor.GetSelection() and a selection filter instead of Editor.GetEntity() and then, for each selected entity, prompt the user to specify the insertion point and add the attribute reference.

[Anonymous]

Can u send me the code

[_gile · Accepted solution]

Claiming a code is not a good way to learn.

        [CommandMethod("ADDATTREF")]
        public static void AddAttributeReference()
        {
            var doc = Application.DocumentManager.MdiActiveDocument;
            var db = doc.Database;
            var ed = doc.Editor;

            // display a dialog box to get the attribute value
            string attValue;
            using (var dialog = new AttributeValueDialog())
            {
                if (Application.ShowModalDialog(dialog) != System.Windows.Forms.DialogResult.OK)
                    return;
                attValue = dialog.AttributeValue;
            }

            // prompts the user to select block references
            var filter = new SelectionFilter(new[] { new TypedValue(0, "INSERT") });
            var psr = ed.GetSelection(filter);
            if (psr.Status != PromptStatus.OK)
                return;
            dynamic acadApp = Application.AcadApplication;

            using (var tr = db.TransactionManager.StartTransaction())
            {
                foreach (SelectedObject so in psr.Value)
                {
                    var br = (BlockReference)tr.GetObject(so.ObjectId, OpenMode.ForWrite);
                    br.Highlight();
                    // prompts the user to specify the attribute insertion point
                    var ppr = ed.GetPoint("\nSpecify the attribute insertion point: ");
                    br.Unhighlight();
                    if (ppr.Status != PromptStatus.OK)
                        continue;
                    var insPoint = ppr.Value.TransformBy(ed.CurrentUserCoordinateSystem);
                    var attRef = new AttributeReference(insPoint, attValue, "TAG", db.Textstyle)
                    { LockPositionInBlock = false };
                    br.AttributeCollection.AppendAttribute(attRef);
                    tr.AddNewlyCreatedDBObject(attRef, true);
                    db.TransactionManager.QueueForGraphicsFlush();
                }
                tr.Commit();
            }
        }