JavaScript: Formdata append null value - NumberFormatException

Question

The following client code

FormData formData = FormData(document.getElementById(formElemId));
formData.append('version', null);

when received in Server Side via Spring MVC as below

@RequestParam(value = 'version', required = false) Integer versionNumber

throws the following exception

Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer'; nested exception is java.lang.NumberFormatException: For input string: "null"

Alien · Accepted Answer · 2018-11-08 10:52:07Z

0

You can resolve this issue by adding defaultValue like below.

@RequestParam(value = "version", required = false, defaultValue = "0") Integer versionNumber

see documentation

answered Nov 8, 2018 at 10:52

Alien

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5 Comments

Mohan Krishnan Over a year ago

Unfortunately I cannot set a default value to the version (Application Logic). I'll have to handle the null in client itself. So I was wondering what turns my null object in client to string null when received in server.

Alien Over a year ago

actually it was a bug in previous versions which has been resolved now...try with latest versions defaultValue is not needed.

Mohan Krishnan Over a year ago

Oh thanks for that. Can you please let me know on which version is this bug was fixed. Am currently on 4.3.9

Alien Over a year ago

This was considered a bug in 2013: jira.spring.io/browse/SPR-10180 and was fixed with version 3.2.2. Problem shouldn't occur in any versions after that and your code should work just fine.

frank Over a year ago

With the latest spring boot, if I use @ModelAttribute, this exception still exist

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