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So I created my grammar xtext in which I declared a part View, a part Model, and another for controller (MVC), then I generated my model and now I'm modeling using Sirius I created Also my palette, and I was able to drag items, but my problem is when I want to save my diagram, I always have an error " Save Failed Java.lang.NullPointerException ". I don't know why this error and how to solve it, thank you for helping me.enter image description here

Senoussaoui Ikram
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  • Look in the .log file in the workspace .metadata directory to see is there is a more detailed stack trace. If there is edit your question and add the trace. – greg-449 Mar 07 '17 at 14:32

1 Answers1

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It might be (but without the actual stacktrace it's speculation) that your model in memory does not fit the constraints imposed by your grammar. Another way to put it is: your grammar can't seraialize the model in the state it is. Let's imagine you are working with Java, and you have an instance of a JavaClass in memory but no name for it, then the Java grammar won't allow to serialize it as the name in 

public class Name {

}

is mandatory.

If you are not yet aware of this presentation you might want to have a look at it as it covers most of the issues you have to handle when mixing Sirius and Xtext.

Cédric Brun
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