CODEWITHSUNDEEP
javaspringspring-boot
refinish_devloper
refinish_devloper

Reputation: 57

Receiving unstructured JSON files in Spring Resources

Currently I have a Resource as follows

@PostMapping("/color")
public String addColorData(@RequestBody Object obj){
    System.out.println(obj.toString());
    return "200";
}

and when I POST the JSON bellow

{ "color" : "Green", "mixutres" : { "Yellow" : 0.5, "random2" : 0.5 } }

the print is as expected - {color=Green, mixutres={Yellow=0.5, random2=0.5}}

However,

When I make a class Color

public class Color  {

    private String color;

    private Object mixtures;


    public Object getMixtures() {
        return mixtures;
    }

    public void setMixtures(Object mixtures) {
        this.mixtures = mixtures;
    }

and modify my Resource as bellow

@PostMapping("/color")
public String addColorData(@RequestBody Color colorObj){
    System.out.println(colorObj.toString());
    return "200";
}

mixtures ends up as 'null'

{color=Green, mixtures='null'}

  1. Why does mixtures end up as 'null'?

  2. Assuming that I don't know the exact structure of mixtures, is setting the Mixtures' type as Object the right approach? If not, could you guys give me some advice for best practices?

Thank you

--- Follow up --

Thanks to Gulliva found a typo in my JSON, when I tested after the edit

Spring returned the following

trace": "org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize instance of java.lang.String out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of java.lang.String out of START_OBJECT token\n at [Source: (PushbackInputStream); line: 5, column: 18] (through reference chain:

.... "message": "JSON parse error: Cannot deserialize instance of java.lang.String out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of java.lang.String out of START_OBJECT token\n at [Source: (PushbackInputStream); line: 5, column: 18] (through reference chain:

Upvotes: 1

Views: 394

Answers (2)

Nitesh Sharma
Nitesh Sharma

Reputation: 555

If your structure is just key pair value then you can use Map<String, String> mixtures which is my preferred ds and your class would look like this :

public class Color  {

private String color;

private Map<String, String> mixtures;


public Map<String,String> getMixtures() {
    return mixtures;
}

public void setMixtures(Map<String,String> mixtures) {
    this.mixtures = mixtures;
}

As by taking collection type of structure would be helpful in future as well for data accessing/modifying.

Upvotes: 1

Gulliva
Gulliva

Reputation: 488

If your example at top is correct, then you have a Typo in the key "mixtures".

One suggestions here. Consider to use ResponseBody to as your ResponseEntity. Since ResponseBody is a generic class you can use it with the type you like and set a HTTP StatusCode like

ResponseEntity.ok("hello world);

Upvotes: 0

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