Java | Validating JSON objects inside wrapper

Question

I am working with Java Spring framework and receive a JSON on input. It consists of an array of thousands of MyObjects. I would like the application to throw exception if one of the MyObjects or AnotherObjects fails a constraint (@NotNull or @Size). So far, the application throws NullPointerException once it is accessing the null field when doing something with the object - not during its construction.

My question is:

Is there a way to check the constraints of nested JSON objects preferrably with annotation?

The JSON looks like:

{
  "myObjects": [
    {
      "code": "PQ",
      "another_objects": [
        {
          "attr1": "value1",
          "attr2": "value2",
          "attrN": "valueN"
        },
        {
          "attr1": "value1",
          "attr2": "value2",
          "attrN": "valueN"
        }
      ]
    },
    {
      ...
    }
  ]
}

The servlet looks like:

@RequestMapping(value = ...)
public final void doSomething(@Valid @RequestBody MyObjectWrapper wrapper) {
    // do something very time-heavy here
}

The objects are defined as follows:

public class MyObjectWrapper {
    private List<MyObject> myObjects;

    public List<MyObject> getMyObjects() {
        return myObjects;
    }

    public void setMyObjects(List<MyObjects> myObjects) {
        this.myObjects = myObjects;
    }
}

And the MyObject class:

public class MyObject {

    @NotNull
    @NotEmpty(message = ...)
    List<AnotherObject> anotherObjects;

    @NotNull
    @Size(min = 2, max = 2, message = ...)
    String code;

    @JsonCreator
    public MyObject(@JsonProperty("another_objects") List<AnotherObjects> anotherObjects,
                    @JsonProperty("code") String code) {
        this.code = code;
        this.anotherObjects = anotherObjects;
    }

    /*  getters and setters */
}

The AnotherObjects is similar but consists of Strings only.

StanislavL · Accepted Answer · 2017-08-10 07:22:55Z

5

Add @Valid to the nested object of the wrapper

public class MyObjectWrapper {
    @Valid
    private List<MyObject> myObjects;

    public List<MyObject> getMyObjects() {
        return myObjects;
    }

    public void setMyObjects(List<MyObjects> myObjects) {
        this.myObjects = myObjects;
    }
}

answered Aug 10, 2017 at 7:22

StanislavL

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