get value of specific attribute to var

[renanemeyer]

Hello everybody.
I'm wanting a "basic thing" but I can't implement it in my code.
I need to get a specific value of an attribute in a specific block and then use it in the lisp.

It would be the value 11 of the BlkLocal block.

First I did a function in my lisp to get the value:

(defun get-attrib-value (blk-name tag)
    (vlax-for blk (vla-get-ModelSpace (vla-get-ActiveDocument (vlax-get-acad-object)))
        (if (and (= (vla-get-ObjectName blk) "AcDbBlockReference") (= (vla-get-Name blk) blk-name))
            (vlax-for attdef blk
                (if (= (vla-get-TagString attdef) tag)
                    (return (vla-get-TextString attdef))
                )
            )
        )
    )
    ""
)

Then I used:

(setq VarX (get-attrib-value "BlkLocal" "11"))

but it returns empty.
I tried to understand a code found at:

https://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/how-can-extract-attribute-informatio...

however it scans and displays all.
Do you have an easy method to fix this VarX that shows empty even though it's not empty?

[ronjonp]

Try this small change .. this code is horribly inefficient though because you are going through the entire drawing to get one value.

(defun get-attrib-value	(blk-name tag)
  (vlax-for blk	(vla-get-modelspace (vla-get-activedocument (vlax-get-acad-object)))
    (if	(and (= (vla-get-objectname blk) "AcDbBlockReference") (= (vla-get-name blk) blk-name))
      (vlax-for	attdef blk
	(if (= (vla-get-tagstring attdef) tag)
	  (setq return (vla-get-textstring attdef))
	)
      )
    )
  )
  return
)

Use the 'get-attribute' function HERE in that same thread you linked to.

[renanemeyer]

thanks for the tip and help with this @ronjonp 
however I try to run it (modified as below just to display)

(defun get-attrib-value	(blk-name tag / return)
  (vlax-for blk	(vla-get-modelspace (vla-get-activedocument (vlax-get-acad-object)))
    (vlax-for b	blk
      (if (and (= (vla-get-objectname b) "AcDbBlockReference") (= (vla-get-name b) blk-name))
	(vlax-for attdef b
	  (and (= (vla-get-tagstring attdef) tag) (setq return (vla-get-textstring attdef)))
	)
      )
    )
  )
  return
)

(defun c:AttValue ()
  (setq VarX (get-attrib-value "BlkLocal" "11")))
  (if VarX 
    (progn
      (princ "\nValue is: ")
      (princ VarX)
    )
    (princ "\nAtt not found.")
  )
  (princ)
)

and even with the block, it doesnt find the value.
even in a new drawing it isnt found.
I tried to change it to vla-get-paperspace because I'm going to use it in the layout, even there, in a new drawing, a new bloc... error: Unknown name.
=//

[ronjonp]

My bad .. code updated above it had an error in it. Are your blocks dynamic? If not we can filter them directly without iterating over the entire layout.

[renanemeyer]

Alright, I tried to rewrite the code several ways (I adjusted the get-attrib-value function to return an empty string if the attribute is not found, instead of nil) but I hadn't thought about this possibility of filtering it.
It is not dynamic, it is a normal block and is present only in Layout1

[ronjonp]

Try this .. it will store the value in 'return'. You need to supply the correct blockname and tagstring.

(if (setq s (ssget "_X" '((0 . "INSERT") (66 . 1) (2 . "NAME_OF_YOUR_BLOCK"))))
  (foreach att (vlax-invoke (vlax-ename->vla-object (ssname s 0)) 'getattributes)
    (and (= (vla-get-tagstring att) "NAME_OF_TAGSTRING") (setq return (vla-get-textstring att)))
  )
)

[renanemeyer · Accepted solution]

@ronjonp 
I did the test and it didn't work (I did several other variations and I'll leave a comment on how the one that worked in case you or anyone visiting also goes through something similar)
I used the entnext function with no arguments to get the first entity in the drawing.

(defun get-attrib-value (blk-name tag / all-entities att val)
  (setq all-entities (entnext))
  (while all-entities
    (if (and (= (cdr (assoc 0 (entget all-entities))) "INSERT")
             (= (cdr (assoc 2 (entget all-entities))) blk-name))
      (progn
        (setq att (entnext all-entities))
        (while (and att (not val))
          (if (and (= (cdr (assoc 0 (entget att))) "ATTRIB")
                   (= tag (cdr (assoc 2 (entget att)))))
            (setq val (cdr (assoc 1 (entget att))))
          )
          (setq att (entnext att))
        )
      )
    )
    (setq all-entities (entnext all-entities))
  )
  val
)

@ 

[Sea-Haven]

You dont need the tagname if you want the 11th attribute, a couple of ways can loop with a counter till get to 11 and retrieve that attribute, or can get the 11th attribute directly (nth (- 11 1) atts)

(setq blk (vlax-ename->vla-object (car (entsel "\nPick title block "))))
(setq atts (vlax-invoke blk 'getattributes))
(setq att (nth 10 atts))
(setq txt11 (vlax-get att 'textstring))

[renanemeyer]

Yes, @Sea-Haven yours is a great idea.
Only on this occasion is it not so viable as you would only need to store it in a variable to use it later, doing so without the need to select the block manually.
Thanks for sharing