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Recent Posts
Vaadin Forum3. Vaadin 6, 7, 8Framework UI

Strange Form behaviour with NestedMethodProperty

Ajay Bathula
10 years ago Feb 27, 2012 5:13am

Hi

I have a form which has NestedMethodProperty for one of the form field's bean property when i set that field as not mandory i see a strange NullPointerexception on the client side in the browser but nothing at the server side. But if i set the field as required i don't see any error. Why is this strange behaviour caused. I have been strugling with this error for the past three days without any clue. See the attachment of the screen shot

Regards
Ajay

Ajay Bathula
10 years ago Feb 28, 2012 5:01am

Problem solved.

To avoid Null pointer exception on Nested method property's getValue method we have to create empty objects. As @NestedMethodProperty mandates that all intermediate getters must return non-null values.

Henri Sara
10 years ago Feb 28, 2012 7:11am

Ajay Kumar Bathula: To avoid Null pointer exception on Nested method property's getValue method we have to create empty objects. As @NestedMethodProperty mandates that all intermediate getters must return non-null values.

This is related to enhancement request #7229 to add an option to treat intermediate nulls as nulls for the nested property.

David Modino
9 years ago Jul 20, 2012 6:52am

Hi Ajay,

Could you explain better with an example how you have done to solve that problem?

Thanks in advance.

Juan Osuna
9 years ago Jul 20, 2012 11:15pm

David Modino: Hi Ajay,

Could you explain better with an example how you have done to solve that problem?

Thanks in advance.

You can take a look at a "hack" I used in ExpressUI:
https://github.com/juanosuna/expressui-framework/blob/master/expressui-core/src/main/java/com/vaadin/data/util/EnhancedNestedMethodProperty.java
If a null occurs anywhere in the nested property path, then null is returned. And if a value is set on a nested property path that contains nulls, empty values are automatically created using reflection and inserted into the tree.

You can see in my live demo that nested properties are used quite a lot in various results and forms.

Juan

Last updated on Jul, 20th 2012
Rodrigo Rodrigues
8 years ago Dec 12, 2013 11:47pm

Hi I'm using the vaadin 7.1.7 and this exception still happens, I didn't understand how to fix it!

Henri Sara
8 years ago Dec 13, 2013 10:14am

The javadoc for NestedMethodProperty and some of the methods using it implicitly specifies that there should not be any intermediate nulls along the path, so it works as specified.

However, in the Vaadin 7.2 branch the behavior has been changed so that intermediate nulls simply produce null as the result, and we are considering introducing the change even in Vaadin 7.1.x (#12884) despite it resulting in a minor API change.

Rodrigo Rodrigues
8 years ago Dec 15, 2013 12:48am

Hi, thanks for reply, but is there any way to avoid this error?

Maybe the problem here is not the same issue that occurs with me, I have created a new post here about this issue

https://vaadin.com/forum#!/thread/4553858