Can we add validation to the request body based on the request Parameter

Question

I have an REST endpoint, which takes an object in the request body and a request parameter. When the request parameter is passed, I need to validate all the attributes of the object, if not the parameter takes the default value assigned and only 2 attributes needs to be validated. The path needs to be same for both the case. How can this be achieved?

Currently I have pattern, length and possibles values check for the objects, validated with the help of annotations.

----- Updating the Class -------

@ValidateParent(parent = "parent ", child= "child")
public class anClass{

    @NotNull(groups = {FrstValidator.class, SndValidator.class})
    @Pattern(regexp = "^[a-zA-Z]{3}$",
            groups = {FrstValidator.class, SndValidator.class})
    String str1;

    @NotNull(groups = {FrstValidator.class, SndValidator.class})
    @Pattern(regexp = "^[a-zA-Z]{3}$",
            groups = {FrstValidator.class, SndValidator.class})
    String str2;

    @Pattern(regexp = "^[a-zA-Z]{10}$",
            groups =  SndValidator.class)
    String child;

    @Pattern(regexp = "^[a-zA-Z]{10}$",
            groups = SndValidator.class)
    String parent;

    @Pattern(regexp = "^[a-zA-Z]{10}$",
            groups = SndValidator.class)
    String str3;


}

ValidateParent, checks if the parent is also passed when the child is passed in the request body.

Answer 1

You can achieve your goal in an elegant "Spring way", using validation groups and two separate endpoints, distinguished by presence of the request parameter:

Validation groups:

// Validation groups are just marker interfaces
private interface PartialValidation {}
private interface FullValidation {}

Request DTO:

@Data
private static class Request {
    // This field will be validated only for FullValidation validation group
    @NotNull(groups = FullValidation.class)
    String field1;
    // This field will be validated for both validation groups
    @NotNull(groups = {FullValidation.class, PartialValidation.class})
    String field2;
}

Controller:

// This endpoint is executed only if there is no myParam preprovided
@PostMapping(
    value = "/validation",
    params = "!myParam")
public void partialValidation(
    @RequestParam(defaultValue = "DEFAULT") String myParam,
    // Request is validated against the PartialValidation group
    @RequestBody @Validated(PartialValidation.class) Request request) {

    System.out.println("Partial validation");
}

// This endpoint is executed only if there is myParam preprovided
@PostMapping(
    value = "/validation",
    params = "myParam")
public void fullValidation(
    @RequestParam String myParam,
    // Request is validated against the FullValidation group
    @RequestBody @Validated(FullValidation.class) Request request) {

    System.out.println("Full validation");
}