How to know if a DXF property exist in an autocad object with lisp

[JovanG]

Hi dear team. Wish you a great day

 

I was wondering if there is a way to know if a DXF property exist on selected objects:

For example:

(setq ss (ssget "something"))

(if (exist DXF code 3 in ss) (prompt "\nThe DXF code 3 exist in selected object") (prompt "\nThe DXF code 3 doesn`t exist in selected object"))

[pkenewell]

@JovanG Look at using (assoc), it returns nil if the DXF code is not present.

 

Example:

(assoc 3 (entget (car (entsel))))

Paste this at the command line and select a longer mtext and a short mtext

 

If you are iterating through the selection set it would be something like this snippet of code:

(defun massoc (key alist / x nlist)
   (foreach x alist
      (if
         (eq key (car x))
         (setq nlist (cons x nlist))
      )
   )
   (reverse nlist)
) ;defun

(setq cnt -1)
(repeat (sslength ss)
  (setq en (entget (ssname ss (1+ cnt))))
  (if (assoc 3 en)
     (progn
         (setq str
             (apply 'strcat
			    (cons
                   (mapcar 'cdr (massoc 3 en))
                   (cdr (assoc 1 en))
                )
             )
         )
         ; .. do something ..
      )
     (progn
        (setq str (cdr (assoc 1 en)))
        ; .. do something ..
     )
   )
)

EDIT - corrected! The (apply) statement should've has 'strcat, not 'append

Edited January 27, 2021 by pkenewell

[JovanG]

19 minutes ago, pkenewell said:

Look at using (assoc), it returns nil if the DXF code is not present.

Excellent! Thank you very much @pkenewell. That was just what I needed