Binding a list in @RequestParam

Question

I'm sending some parameters from a form in this way:

myparam[0]     : 'myValue1'
myparam[1]     : 'myValue2'
myparam[2]     : 'myValue3'
otherParam     : 'otherValue'
anotherParam   : 'anotherValue' 
...

I know I can get all the params in the controller method by adding a parameter like

public String controllerMethod(@RequestParam Map<String, String> params){
    ....
}

I want to bind the parameters myParam[] (not the other ones) to a list or array (anything that keeps the index order), so I've tried with a syntax like:

public String controllerMethod(@RequestParam(value="myParam") List<String> myParams){
    ....
}

and

public String controllerMethod(@RequestParam(value="myParam") String[] myParams){
    ....
}

but none of them are binding the myParams. Even when I add a value to the map it is not able to bind the params:

public String controllerMethod(@RequestParam(value="myParam") Map<String, String> params){
    ....
}

Is there any syntax to bind some params to a list or array without having to create an object as @ModelAttribute with a list attribute in it?

Thanks

I don't think this is possible. The code in `HandlerMethodInvoker.resolveRequestParam` only ever gets the first value — skaffman, Jan 04 '11 at 17:16
(*Spring Boot*): Is about `method = RequestMethod.GET` or `method = RequestMethod.POST`? If `.GET` `@RequestParam List groupVal` fulfilled from `?groupVal=kkk,ccc,mmm` successfully (*Spring Boot*) — basil, Aug 06 '16 at 13:45

score 123 · Answer 1 · answered Apr 11 '11 at 15:54

123

Or you could just do it that way:

public String controllerMethod(@RequestParam(value="myParam[]") String[] myParams){
    ....
}

That works for example for forms like this:

<input type="checkbox" name="myParam[]" value="myVal1" />
<input type="checkbox" name="myParam[]" value="myVal2" />

This is the simplest solution :)

answered Apr 11 '11 at 15:54

Bernhard

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4

does that preserve the order? – andrew cooke Jan 24 '12 at 19:53
9

I was able to use just the name rather than the [] in Spring 3.0 thusly: @RequestParam(value="myParam") String[] myParams – M Smith Apr 24 '12 at 18:40
3

I do not share the findings of @MSmith, though. – Pedro Nov 29 '12 at 02:36
3

Is it possible to obtain `List` through this. Also is it possible to obtain a java bean like `List` – Juzer Ali Apr 24 '13 at 15:14
4

I think you can remove the brackets from param name. – theblang Oct 08 '13 at 21:26
1

Works without brackets, but they may be needed if you use jQuery to push each selected checkbox into array and send it as param. – yosh Jul 14 '14 at 11:56
With jQuery, I found that sending it as a comma separated string seemed to work: `var array = '1,5,33';` – Ian Newland Jun 28 '16 at 14:31
It does not work with this kind of url: `&order[0][column]=1&order[0][dir]=desc`? – zygimantus May 07 '17 at 09:57
Using `myParam[]` saved me. Using just `myParam` didn't work. – Top Cat Dec 08 '18 at 01:20
I used '@RequestParam(value = "ot-replace[]") String[] otReplace' but still getting Invalid character found in the request target – WISHY Jul 15 '22 at 06:36

score 109 · Accepted Answer · edited Apr 11 '11 at 17:25

109

Arrays in @RequestParam are used for binding several parameters of the same name:

myparam=myValue1&myparam=myValue2&myparam=myValue3

If you need to bind @ModelAttribute-style indexed parameters, I guess you need @ModelAttribute anyway.

edited Apr 11 '11 at 17:25

Donal Fellows

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answered Jan 04 '11 at 17:19

axtavt

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there may be problems with the order (which is very important to keep in my case) because I send the parameters by serializing a form and sending i with ajax. I'll use the "traditional" @ModelAttribute way. – Javi Jan 05 '11 at 08:07
Would you happen to know how to construct a URI with this sort mapping with UriTemplate, or some other means? (for a client of this sort of resource). – Chomeh May 04 '15 at 04:24
Answering my own question, it apears the spring UriTemplate doesn't support RFC6570, use the damnhandy implementation: http://stackoverflow.com/questions/14153036/how-to-send-array-with-spring-resttemplate – Chomeh May 04 '15 at 06:54

score 39 · Answer 3 · edited Sep 05 '18 at 12:31

39

Subscribing what basil said in a comment to the question itself, if method = RequestMethod.GET you can use @RequestParam List<String> groupVal.

Then calling the service with the list of params is as simple as:

API_URL?groupVal=kkk,ccc,mmm

edited Sep 05 '18 at 12:31

dube

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answered Feb 13 '17 at 10:45

Juangui Jordán

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I have a small problem. What should i do if one of the string element contains ',' and the url decodes this as two separated string element. – Jimmy lau Jan 24 '22 at 07:59
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@Jimmylau You have to escape the string. "," can be escaped with "%2C". – Alexander Holland Nov 25 '22 at 07:05

score 25 · Answer 4 · answered Feb 17 '16 at 19:53

25

Just complementing what Donal Fellows said, you can use List with @RequestParam

public String controllerMethod(@RequestParam(value="myParam") List<ObjectToParse> myParam){
....
}

Hope it helps!

answered Feb 17 '16 at 19:53

Jorge Peres

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score 10 · Answer 5 · edited Mar 25 '18 at 13:31

10

One way you could accomplish this (in a hackish way) is to create a wrapper class for the List. Like this:

class ListWrapper {
     List<String> myList; 
     // getters and setters
}

Then your controller method signature would look like this:

public String controllerMethod(ListWrapper wrapper) {
    ....
}

No need to use the @RequestParam or @ModelAttribute annotation if the collection name you pass in the request matches the collection field name of the wrapper class, in my example your request parameters should look like this:

myList[0]     : 'myValue1'
myList[1]     : 'myValue2'
myList[2]     : 'myValue3'
otherParam    : 'otherValue'
anotherParam  : 'anotherValue'

edited Mar 25 '18 at 13:31

naXa stands with Ukraine

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answered Jan 06 '11 at 19:26

driangle

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Well this is almost the same as using @ModelAttribute, the only difference is that the param is not annotated. I wanted to avoid @ModelAttribute just because I didn't want to create a wrapper. I read somewhere in stackoverflow (I can't remember where exactly) that if you add a param in the controller method without @ModelAttribute annotation (and it wasn't a special object like HttpRequest, HttpResponse...) the framework treat it as if it were annotated with @ModelAttribute. So if that was true this is exactly as having @ModelAttribute. But thanks for your answer. – Javi Jan 06 '11 at 19:41
@driangle I have a similar case but I have 2 Sets of and I wrap them both in one object. However after I do it I can no longer use comma separated syntax to assign values to my sets. If I do ?idsType1=QWE,RTY,UIO I am getting one element with "QWE,RTY,UIO" as value. SpringBoot 2.1.1.RELEASE, Java 8 openjdk – Marcin K. Dec 13 '22 at 09:16

score 6 · Answer 6 · answered Jan 16 '19 at 14:23

It wasn't obvious to me that although you can accept a Collection as a request param, but on the consumer side you still have to pass in the collection items as comma separated values.

For example if the server side api looks like this:

@PostMapping("/post-topics")
public void handleSubscriptions(@RequestParam("topics") Collection<String> topicStrings) {

    topicStrings.forEach(topic -> System.out.println(topic));
}

Directly passing in a collection to the RestTemplate as a RequestParam like below will result in data corruption

public void subscribeToTopics() {

    List<String> topics = Arrays.asList("first-topic", "second-topic", "third-topic");

    RestTemplate restTemplate = new RestTemplate();
    restTemplate.postForEntity(
            "http://localhost:8088/post-topics?topics={topics}",
            null,
            ResponseEntity.class,
            topics);
}

Instead you can use

public void subscribeToTopics() {

    List<String> topicStrings = Arrays.asList("first-topic", "second-topic", "third-topic");
    String topics = String.join(",",topicStrings);

    RestTemplate restTemplate = new RestTemplate();
    restTemplate.postForEntity(
            "http://localhost:8088/post-topics?topics={topics}",
            null,
            ResponseEntity.class,
            topics);
}

The complete example can be found here, hope it saves someone the headache :)

score -10 · Answer 7 · edited Dec 01 '15 at 19:09

-10

Change hidden field value with checkbox toggle like below...

HTML:

<input type='hidden' value='Unchecked' id="deleteAll" name='anyName'>
<input type="checkbox"  onclick="toggle(this)"/> Delete All

Script:

function toggle(obj) {`var $input = $(obj);
    if ($input.prop('checked')) {

    $('#deleteAll').attr( 'value','Checked');

    } else {

    $('#deleteAll').attr( 'value','Unchecked');

    }

}

edited Dec 01 '15 at 19:09

Giancarlo Abel Giulian

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answered Feb 05 '15 at 20:04

Khomeni

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Was this attempting to answer the OP at all ? Doesn't seem related. – James Gawron Apr 08 '22 at 16:30

Binding a list in @RequestParam

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