Spring MVC populate @RequestParam Map

Question

I have the following method in my Spring MVC @Controller :

@RequestMapping(method = RequestMethod.GET)
public String testUrl(@RequestParam(value=\"test\") Ma         


        

Answer 1

You can create a new class that contains the map that should be populated by Spring and then use that class as a parameter of your @RequestMapping annotated method.

In your example create a new class

public static class Form {
   private Map<String, String> test;
   // getters and setters
}

Then you can use Form as a parameter in your method.

@RequestMapping(method = RequestMethod.GET)
public String testUrl(Form form) {
  // use values from form.getTest()
}

Answer 2

Spring doesn't have default conversion strategy from multiple parameters with the same name to HashMap. It can, however, convert them easily to List, array or Set.

@RequestMapping(value = "/testset", method = RequestMethod.GET)
    public String testSet(@RequestParam(value = "test") Set<String> test) {

        return "success";
    }

I tested with postman like http://localhost:8080/mappings/testset?test=ABC&test=DEF

You will see set having data, [ABC, DEF]

Answer 3

As detailed here https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestParam.html

If the method parameter is Map or MultiValueMap and a parameter name is not specified, then the map parameter is populated with all request parameter names and values.

So you would change your definition like this.

@RequestMapping(method = RequestMethod.GET)
public String testUrl(@RequestParam Map<String, String> parameters) 
{   
  (...)
}

And in your parameters if you called the url http://myUrl?A=ABC&B=DEF

You would have in your method

parameters.get("A");
parameters.get("B");

Answer 4

Your question needs to be considered from different points of view.

1. first part:

as is mentioned in the title of the question, is how to have Map<String, String> as @RequestParam.

Consider this endpoint:

@GetMapping(value = "/map")
public ResponseEntity getData(@RequestParam Map<String, String> allParams) {
    String str = Optional.ofNullable(allParams.get("first")).orElse(null);
    return ResponseEntity.ok(str);
}

you can call that via:

http://<ip>:<port>/child/map?first=data1&second=data2

then when you debug your code, you will get these values:

> allParams (size = 2)
    > first = data1
    > second = data2

and the response of the requested url will be data1.

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2. second part:

as your requested url shows (you have also said that in other answers' comments) ,you need an array to be passed by url.

consider this endpoint:

public ResponseEntity<?> getData (@RequestParam("test") Long[] testId,
                                  @RequestParam("notTest") Long notTestId)

to call this API and pass proper values, you need to pass parameters in this way:

?test=1&test=2&notTest=3

all test values are reachable via test[0] or test[1] in your code.

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3. third part:

have another look on requested url parameters, like: test[B]

putting brackets (or [ ]) into url is not usually possible. you have to put equivalent ASCII code with % sign.

for example [ is equal to %5B and ] is equal to %5D.

as an example, test[0] would be test%5B0%5D.

more ASCII codes on: https://ascii.cl/