Binding Arrays - Cannot read properties of undefined (reading '0')

[shinusuresh]

Describe the bug

Following the documentation https://vaadin.com/docs/latest/hilla/guides/forms/binding-arrays is giving the error while trying to bind items

Error handled by React Router default ErrorBoundary: TypeError: Cannot read properties of undefined (reading '0')
    at _BinderNode.initializeValue (chunk-HYT7HGKV.js?v=b6b40b33:1386:64)
    at _BinderNode (chunk-HYT7HGKV.js?v=b6b40b33:1145:12)
    at getBinderNode (chunk-HYT7HGKV.js?v=b6b40b33:1085:12)
    at [Symbol.iterator] (chunk-HYT7HGKV.js?v=b6b40b33:1042:13)
    at ArrayModel.next (<anonymous>)
    at Function.from (<anonymous>)
    at useFormArrayPart (@vaadin_hilla-react-form.js?v=b6b40b33:202:18)
    at GroupFormView (@index.tsx:20:38)
    at renderWithHooks (chunk-SV5EQZIV.js?v=b6b40b33:11548:26)
    at updateFunctionComponent (chunk-SV5EQZIV.js?v=b6b40b33:14582:28)
    at beginWork (chunk-SV5EQZIV.js?v=b6b40b33:15924:22)
    at beginWork$1 (chunk-SV5EQZIV.js?v=b6b40b33:19753:22)
    at performUnitOfWork (chunk-SV5EQZIV.js?v=b6b40b33:19198:20)
    at workLoopSync (chunk-SV5EQZIV.js?v=b6b40b33:19137:13)
    at renderRootSync (chunk-SV5EQZIV.js?v=b6b40b33:19116:15)
    at performSyncWorkOnRoot (chunk-SV5EQZIV.js?v=b6b40b33:18874:28)
    at flushSyncCallbacks (chunk-SV5EQZIV.js?v=b6b40b33:9119:30)
    at chunk-SV5EQZIV.js?v=b6b40b33:18627:21

Expected-behavior

No error is expected while adding person

Reproduction

https://github.com/shinusuresh/hilla-form-binding-array-issue.git

System Info

Operating System: MacOS
Hilla Version: 24.5.7
Browser Type: Chrome

[lloydchandran]

I am also facing this problem . There is a problem with array initilization . My expectation was Model.createEmptyValue on a parent object with an array will initialize it . But it’s not happening

[lloydchandran]

@platosha . This looks like basic feature that should work out of the box. Do you see any problems in the way it got implemented ?

[platosha]

Thanks for reporting. The implementation in the project looks fine from the first glance. I'll try to reproduce and get back with more info.

[platosha]

I am also facing this problem . There is a problem with array initilization . My expectation was Model.createEmptyValue on a parent object with an array will initialize it . But it’s not happening

Small clarification by the way, Model.createEmptyValue() simply returns a value, the call alone does not change anything anywhere.

[platosha]

There is a bug in the form library around on demand initialization of nullable arrays. I'm working on a fix.

Meanwhile, as a workaround, try using Nonnull annotation. A helpful shortcut is to add it globally to the API package. Add package-info.java with the following content:

@NonNullApi
package com.example.application;

import org.springframework.lang.NonNullApi;