Is it possible to have empty RequestParam values use the defaultValue?

Question

if I have a a request mapping similar to the following:

@RequestMapping(value = "/test", method = RequestMethod.POST)
@ResponseBody
public void test(@RequestParam(value = "i", defaultValue = "10") int i) {
}

And then call this request with:

http://example.com/test?i=

I get the error message

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

I can solve this by either stopping the javascript client from sending empty parameters, or by accepting string values and only parsing if they are not found to be blank.

UPDATE: Later versions of spring now implement the originally desired behaviour.

I've just tested this in spring 4.3.5 and have found that the behaviour will now in fact turn the null value into the default value without raising a NumberFormatException, thus; my original mapping now works fine.

I am not sure which version of spring this behavioural change was made.

surely the parameter would be an Integer type to raise that exception? — laher
– laher, Commented Sep 6, 2012 at 9:13
im not spring expert, but is default value is used when you don't set it? ie if your request will be example.com/test ? as you use example.com/test?i= then i is present and set to "" so default value is not used — user902383
– user902383, Commented Sep 6, 2012 at 9:40
Thanks amir75, accidentally supplied String type. user902383, that's correct, though for an integer value I would prefer that a null/empty value would use the defaultValue instead. — Brett Ryan
– Brett Ryan, Commented Sep 6, 2012 at 9:46

T.Gounelle · Accepted Answer · 2017-10-09 13:26:53Z

226

You could change the @RequestParam type to an Integer and make it not required. This would allow your request to succeed, but it would then be null. You could explicitly set it to your default value in the controller method:

@RequestMapping(value = "/test", method = RequestMethod.POST)
@ResponseBody
public void test(@RequestParam(value = "i", required=false) Integer i) {
    if(i == null) {
        i = 10;
    }
    // ...
}

I have removed the defaultValue from the example above, but you may want to include it if you expect to receive requests where it isn't set at all:

http://example.com/test

edited Oct 9, 2017 at 13:26

T.Gounelle

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answered Sep 22, 2012 at 0:18

Matt

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5 Comments

Brett Ryan Over a year ago

Just an update on this, recent versions of spring actually no longer require the null check as the desired behaviour has been included with spring that empty values will result in the default value being used.

Jose Pose S Over a year ago

Obsolete answers, the best solution is from @AppLend

Dmitriy Popov Over a year ago

In modern Spring versions, it's called defaultValue, and value is just an alias to name.

Sergey Zolotarev Over a year ago

I tried this, but still get the same error: @RequestParam(required = false) Boolean password and then if (password != null && password). My Spring Boot version is 2.6.2

Sergey Zolotarev Over a year ago

Does it return an empty String or something if there's no parameter? What's the workaround?

AppLend · Accepted Answer · 2014-02-20 08:40:02Z

131

You can keep primitive type by setting default value, in the your case just add "required = false" property:

@RequestParam(value = "i", required = false, defaultValue = "10") int i

P.S. This page from Spring documentation might be useful: Annotation Type RequestParam

answered Feb 20, 2014 at 8:40

AppLend

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4 Comments

Brett Ryan Over a year ago

Thanks but you missed the point of my question which is in the title. I've asked for the ability to supply empty params /test?i= and since i is empty have the default value.

Timur Milovanov Over a year ago

Anyway, when defaultValue was provided, required == false implicitly

Brett Ryan Over a year ago

If the param is provided but is empty defaultValue does not take effect.

Dmitriy Popov Over a year ago

Still does not work at least for @GetMapping request. The defaultValue is not set (null for Integer, empty string for String, fails with exception for int. :(

Anand Tagore · Accepted Answer · 2017-02-19 09:38:24Z

20

You can set RequestParam, using generic class Integer instead of int, it will resolve your issue.

   @RequestParam(value= "i", defaultValue = "20") Integer i

answered Feb 19, 2017 at 9:38

Anand Tagore

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Comments

Abd Abughazaleh · Accepted Answer · 2021-08-25 11:16:56Z

5

You can use @Nullable with default value.

@Nullable @RequestParam(value = "i", defaultValue = "10") Integer i

answered Aug 25, 2021 at 11:16

Abd Abughazaleh

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Comments

Tisha · Accepted Answer · 2017-01-19 05:05:06Z

2

You can also do something like this -

 @RequestParam(value= "i", defaultValue = "20") Optional<Integer> i

answered Jan 19, 2017 at 5:05

Tisha

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1 Comment

Kevin M Over a year ago

If you have a defaultValue, there's no need to make this an Optional.

eis · Accepted Answer · 2018-09-01 09:16:56Z

2

This was considered a bug in 2013: https://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.

answered Sep 1, 2018 at 9:16

eis

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