How to represent the ternary associations in Astah

We’ve received several emails from our customers about how to draw N-ary associations using Astah.
Actually, we received one today (Thank you, Salim!). So will write my response in public. 🙂

Here’s one email example (from Arnaud):

I’d ike to know if it is possible to create a multiple association class using a diamond icon ? I did not fnd it on UML 2.5 spec but in some diagrams over the net.

Screen Shot 2019-02-18 at 11.45.53.png
This is the figure from OMG’s Unified Modeling Language 2.5.1 (P. 204).

Currently, Astah doesn’t support it, but there is a way to depict a diamond symbol in Class diagrams.
With Astah, you can upload image files and allocate them to stereotypes. So I’ll show you how to depict N-array relationships using this functionality.

1. First of all, this functionality is available in Astah Professional only – If you don’t have it, get a free trial.

2. Create a project and go to [Tools] – [Project] – [Set Icon for Stereotype]

3. A [Project] dialogue appears. Click [Add] button.

4. One item will be added. Select it and click [Edit] button – which is the pen icon on the right bottom.

5. Upload a diamond image file, add information and specify which Stereotype this image should be related to…etc. I’ll make it related to “n-ary” stereotype for now.



6. Create a diagram, use a Class for where you want to replace with a diamond icon.
sample-uml-class diagram.png


7. Add n-ary stereotype to the Class


8. Keep the focus on the class and go to main menu. Open the drop-down from the icon located 2nd from the right. (Or you can do [Icon Notation] – [Customize Icon] from the Class’s Pop-up menu.)
custom icon.png

9. The Class will turn into the diamond icon.
n-array relationship.png


This functionality is extremely helpful when you want to raise the visibility level of diagrams to make it easier for anyone to understand what your diagrams describe.
Below is one sample diagram Astah user has created using this functionality. With familiar icons or visuals, it is much easier and faster to understand the relations and systems on the diagrams more than a diagram with a bunch of boxes.

Astah stereotype icon

Hope this blog helps you make diagrams more expressive!

– Satomi

One thought on “How to represent the ternary associations in Astah

  1. Thank you. I’ve been looking for this option. However, my diamond still has a class name, unlike your pictures. I can’t figure out how to remove that class name. I’m using Astah professional, 8.2.0/b743f7.

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