Topic: Getting first attribute value in a block

[nobody]

I see lots of examples online to get ALL the values in a block, but is there a way to get just the first one without using a "foreach" and "break"? Seems sufficient enough but feels brutal to the process... what happens if "break" causes an actual break (crash at same time or something)?

Guess I'm used to lisp, where one can specify the attribute value one wants to collect.

Just a noobs curiosity.

Thanks!

[huiz]

You still have to check if there are attributes, so you just can't get the first attribute as GetMyAtrtibute(0).

[nobody]

You still have to check if there are attributes, so you just can't get the first attribute as GetMyAtrtibute(0).

Didn't think about it that way. Thank you!

[huiz]

Don't worry about performance, if I extract attributes and insertion point location from 5000 blocks and put them in a ListView, it takes less then half a second.

[nobody]

Don't worry about performance, if I extract attributes and insertion point location from 5000 blocks and put them in a ListView, it takes less then half a second.

 

[MexicanCustard]

IF you are using Tony T's Runtime Extension Methods you can simplify getting one attribute.

Code: [Select]

var db = Application.DocumentManager.MdiActiveDocument.Database;

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    var bt = (BlockTable)db.BlockTableId.GetObject(OpenMode.ForRead);
    var btr = (BlockTableRecord)bt["MYBLOCK"].GetObject(OpenMode.ForRead);
    var att = btr.Cast<ObjectId>()
        .Where(id=> id.IsTypeOf<AttributeDefinition>())  <-- Need Tony T's extension method here
        .Select(id => (AttibuteDefinition)id.GetObject(OpenMode.ForRead))
        .Where(att => att.Tag == "MY_TAG")
        .FirstOrDefault();
    if (att != null)
    {
        //Do what you want with the single attribute
    }
}

If you know that its a specific block and it always has specific attributes

Code: [Select]

var db = Application.DocumentManager.MdiActiveDocument.Database;

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    var bt = (BlockTable)db.BlockTableId.GetObject(OpenMode.ForRead);
    var btr = (BlockTableRecord)bt["MYBLOCK"].GetObject(OpenMode.ForRead);
    var att = btr.GetObjects<AttributeDefinition>().FirstOrDefault(a=>a.Tag == "MY_TAG);
    if (att != null)
    {
        //Do what you want with the single attribute
    }
}


[bargool]

IF you are using Tony T's Runtime Extension Methods

Could you post link to this methods, please?

[nobody]

IF you are using Tony T's Runtime Extension Methods

Could you post link to this methods, please?

2nd this

[MexicanCustard]

http://www.theswamp.org/index.php?topic=41371.msg464900#msg464900

[bargool]

Oh ye! Thank you!

[nobody]

http://www.theswamp.org/index.php?topic=41371.msg464900#msg464900

Thank you very much! Who is Tony?

[gile]

Hi Alien,

If you're looking for the first attribute of a block reference (BlockReference) instead of a block definition (BlockTableRecord), you can use some LINQ extension methods:

• Cast<> to convert the AttributeCollection into an IEnumerable<ObjectId> usable with Linq methods.
• Any<> to check if the collection isn't empty.
• First<> to get the iENumerable first item.

Here's a little snippet (assuming br is a BlockReference)

Code - C#: [Select]

1.                 IEnumerable<ObjectId> atts = br.AttributeCollection.Cast<ObjectId>();
2.                 if (atts.Any())
3.                 {
4.                     AttributeReference attRef =
5.                         (AttributeReference)atts.First().GetObject(OpenMode.ForRead);
6.                     // ...
7.                 }
8.                 else
9.                 {
10.                     // ...
11.                 }

[nobody]

Fantastic!!! Thank you!

[TheMaster]

Don't worry about performance, if I extract attributes and insertion point location from 5000 blocks and put them in a ListView, it takes less then half a second.

With WinForms or WPF ?

[huiz]

...
With WinForms or WPF ?

Winforms. Actually it wasn't a listview but a datagrid. I've timed the operation from filtering blocks, extracting attributes and locations of 5250 entities, and in 489 milliseconds the data was placed in the datagrid.