Can Modified on from?

I have stringEdit on form size = 15x23x30cm
and RealEdit width = 15, length = 23, height = 30
value of size is widthXlengthXheight
I want to change width,length,height and value update to size
and I can change value on size and value update to width,length,height

What’s your version of Dynamics AX? It’s different in AX 7 from previous versions. Please always attach a tag with your version so everybody can see immediately see it.

Also, I don’t understand the question. You talk about “size”, but it;s not clear whether it’s size of the StringEdit control, the RealEdit control or the size of the form. And what do you mean by “change value on size”?

Thank you for reply. I use Dynamics AX 4.0
I mean on from field name is “Size” and value “15x23x30cm”,
field name is "width " value “15”,
field name is "length " value “23”,
field name is "height " value “30”.
I would like to edit value “width” to “20” and value on “Size” update to “20x23x30cm”,

Let me summarize how I understand your reply.

You have three RealEdit controls, not just one. Their names are Width, Length and Height.
Then you have a string edit control, Size, which shows values from those RealEdit fields as a formatted string.

Is it correct?

If is, I recommend you write a display method on the table and bind it to your Size field.
The method should return something like strFmt("%1x%2x%3cm", this.Width, this.Length, this.Height).

Thank you Martin Dráb.
That work. If i also want to edit Size field and update to RealEdit fields.

You could use an edit method, parse the string and update field values, but I wouldn’t bother doing it.