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 lt String  String gt  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 lt String gt  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 lt String  String gt  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

User · Answer

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

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

Hope it helps!

User · Answer

One way you could accomplish this  in a hackish way  is to create a wrapper class for the List  Like this    class ListWrapper        List lt String gt  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

User · Answer

Arrays in  RequestParam are used for binding several parameters of the same name   myparam myValue1 amp myparam myValue2 amp myparam myValue3   If you need to bind  ModelAttribute-style indexed parameters  I guess you need  ModelAttribute anyway

User · Answer

Or you could just do it that way   public String controllerMethod  RequestParam value  myParam     String   myParams                That works for example for forms like this    lt input type  checkbox  name  myParam    value  myVal1    gt   lt input type  checkbox  name  myParam    value  myVal2    gt    This is the simplest solution

User · Answer

Subscribing what basil said in a comment to the question itself  if method   RequestMethod GET you can use  RequestParam List lt String gt  groupVal   Then calling the service with the list of params is as simple as   API URL groupVal kkk ccc mmm

User · Answer

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 lt String gt  topicStrings         topicStrings forEach topic - gt  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 lt String gt  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 lt String gt  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

User · Answer

Change hidden field value with checkbox toggle like below     HTML    lt input type  hidden  value  Unchecked  id  deleteAll  name  anyName  gt   lt input type  checkbox   onclick  toggle this    gt  Delete All   Script   function toggle obj    var  input     obj       if   input prop  checked               deleteAll   attr   value   Checked           else            deleteAll   attr   value   Unchecked

[java] Binding a list in @RequestParam

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