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How to draw Entity Relationship Exclusion Arcs?

0 votes

Hi

Its great that Yed supports the Barker ERD "crows foot" diagramming style (http://en.wikipedia.org/wiki/Barker's_Notation).

However one element of this notation doesn't appear to be supported by yEd - the exclusion arc.  See the heading "exclusion arcs" on this page for a description:  http://www.entitymodelling.org/part-two

 

I can find no way to draw such a line in yEd.  Thoughts on how I can do this?

Thanks

asked Jan 10, 2013 in Help by yed_user (220 points)
recategorized Jan 10, 2013 by thomas
Although yEd provides edge adornments that allow you to model crow's foot connections, I am not aware of any mention that yEd would specifically support Barker's Notation...

1 Answer

0 votes

There is no support for this kind of element in yEd, I'm afraid. At least not at the moment.

Short of a better idea, you could try to model it using an arc edge between two invisible nodes, however, that obviously would only be a workaround...

answered Jan 10, 2013 by thomas [yWorks] (23,660 points)
Thomas, could this be a feature request for future versions of yEd?  Do I need to submit such a request separately?

I should mention that there is another acceptable way of doing the exclusionary arcs.  Rather than the arc crossing *ALL* the mutually exclusive relationships (as shown in the picture above) its ok to have a short arc on each relationship which is mutually exclusive and then label each arc with a common label.  

I suspect this would probably be easier to do in yEd since it is just a additional curved line on the relationship (you already have in the Entitiy Relationship Palette cadinality / foreign key short straight lines which cross the relationship line at 90 degrees... so a optional short arc should be "easy"!  

Can I add such an element to the Entity Relationship palette?  (I can send a sketch if you like)
Of course can this be a feature request! You can easily submit it as a separate request (which would be the preferred way), via "ask related question" above.

The alternative way of doing this kind of arcs, where the arc is only on a single edge, actually *is* easier to achieve and would also be more in line with what is supported already.

If you could add a sketch of what the exclusion arc should look like on an edge to your feature request, that would be great. You can't, however, add an edge with such an element to a palette--custom edges are not supported.
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