How to Validate a List of Objects in Spring Controller

How can I successfully validate a list of objects in a Spring controller method?

@RequestMapping(value="/map/update", method=RequestMethod.POST, produces = "application/json; charset=utf-8")
@ResponseBody
public ResponseEntityWrapper updateMapTheme(
        HttpServletRequest request, 
        @RequestBody @Valid List<CompanyTag> categories,
        HttpServletResponse response
        ) throws ResourceNotFoundException, AuthorizationException {
...

In Spring, validating a list of objects is a common requirement for ensuring that the received data meets the defined constraints. The key to successfully validating a list of objects is ensuring that Spring's Validator is configured correctly and that you are utilizing the `@Valid` annotation appropriately.

import org.springframework.validation.annotation.Validated;

@RestController
@RequestMapping(value = "/map")
public class MapController {

    @PostMapping(value="/update", produces = "application/json; charset=utf-8")
    @ResponseBody
    public ResponseEntityWrapper updateMapTheme(
            HttpServletRequest request, 
            @RequestBody @Valid List<CompanyTag> categories,
            HttpServletResponse response
            ) throws ResourceNotFoundException, AuthorizationException {
        // Process validated categories
        return new ResponseEntityWrapper();
    }
}

Causes

• The `@Valid` annotation is not applied correctly to the list of objects in the controller method.
• The validation annotations within the `CompanyTag` class are not set up correctly or are missing.
• The Spring validation process may not be properly configured in the application context.

Solutions

• Ensure that `@Valid` is used on the list type in the controller method signature.
• Check that validation annotations applied in the `CompanyTag` class are correct and functioning, particularly the custom `StringUUIDValidation` annotation.
• Make sure that Spring's validator is correctly configured and that you're using the Spring framework version that supports these features.

Mistake: Not including the @Valid annotation on the List parameter.

Solution: Always include the @Valid annotation when you expect a List to be validated.

Mistake: Failing to properly define validation annotations in the CompanyTag class.

Solution: Review the validation annotations used within the CompanyTag class for correctness and completeness.

Mistake: Assuming that Spring automatically validates nested objects in lists without proper configuration.

Solution: Ensure that appropriate validation settings are enabled in your Spring configuration.