Spring Boot : Custom Validation in Request Params

Question

I want to validate one of the request parameters in my controller . The request parameter should be from one of the list of given values , if not , an error should be thrown . In the below code , I want the request param orderBy to be from the list of values present in @ValuesAllowed.

@RestController
@RequestMapping("/api/opportunity")
@Api(value = "Opportunity APIs")
@ValuesAllowed(propName = "orderBy", values = { "OpportunityCount", "OpportunityPublishedCount", "ApplicationCount",
        "ApplicationsApprovedCount" })
public class OpportunityController {

@GetMapping("/vendors/list")
    @ApiOperation(value = "Get all vendors")

    public ResultWrapperDTO getVendorpage(@RequestParam(required = false) String term,
            @RequestParam(required = false) Integer page, @RequestParam(required = false) Integer size,
            @RequestParam(required = false) String orderBy, @RequestParam(required = false) String sortDir) {

I have written a custom bean validator but somehow this is not working . Even if am passing any random values for the query param , its not validating and throwing an error.

@Repeatable(ValuesAllowedMultiple.class)
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {ValuesAllowedValidator.class})
public @interface ValuesAllowed {

    String message() default "Field value should be from list of ";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};

    String propName();
    String[] values();
}

public class ValuesAllowedValidator implements ConstraintValidator<ValuesAllowed, Object> {

    private String propName;
    private String message;
    private String[] values;

    @Override
    public void initialize(ValuesAllowed requiredIfChecked) {
        propName = requiredIfChecked.propName();
        message = requiredIfChecked.message();
        values = requiredIfChecked.values();
    }

    @Override
    public boolean isValid(Object object, ConstraintValidatorContext context) {
        Boolean valid = true;
        try {
            Object checkedValue = BeanUtils.getProperty(object, propName);

            if (checkedValue != null) {
                valid = Arrays.asList(values).contains(checkedValue.toString().toLowerCase());
            } 

            if (!valid) {
                context.disableDefaultConstraintViolation();
                context.buildConstraintViolationWithTemplate(message.concat(Arrays.toString(values)))
                        .addPropertyNode(propName).addConstraintViolation();
            }
        } catch (IllegalAccessException e) {
            log.error("Accessor method is not available for class : {}, exception : {}", object.getClass().getName(), e);
            return false;
        } catch (NoSuchMethodException e) {
            log.error("Field or method is not present on class : {}, exception : {}", object.getClass().getName(), e);
            return false;
        } catch (InvocationTargetException e) {
            log.error("An exception occurred while accessing class : {}, exception : {}", object.getClass().getName(), e);
            return false;
        }
        return valid;
    }
}

Schilt

Answer 1

Case 1: If the annotation ValuesAllowed is not triggered at all, it could be because of not annotating the controller with @Validated.

@Validated
@ValuesAllowed(propName = "orderBy", values = { "OpportunityCount", "OpportunityPublishedCount", "ApplicationCount", "ApplicationsApprovedCount" })
public class OpportunityController {
@GetMapping("/vendors/list")
public String getVendorpage(@RequestParam(required = false) String term,..{
}

Case 2: If it is triggered and throwing an error, it could be because of the BeanUtils.getProperty not resolving the properties and throwing exceptions.

If the above solutions do not work, you can try moving the annotation to the method level and update the Validator to use the list of valid values for the OrderBy parameter. This worked for me. Below is the sample code.

@RestController
@RequestMapping("/api/opportunity")
@Validated
public class OpportunityController {
    @GetMapping("/vendors/list")
    public String getVendorpage(@RequestParam(required = false) String term,
            @RequestParam(required = false) Integer page, @RequestParam(required = false) Integer size,
            @ValuesAllowed(propName = "orderBy", values = { "OpportunityCount", "OpportunityPublishedCount", "ApplicationCount",
                    "ApplicationsApprovedCount" }) @RequestParam(required = false) String orderBy, @RequestParam(required = false) String sortDir) {
        return "success";
    }

@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = { ValuesAllowed.Validator.class })
public @interface ValuesAllowed {

    String message() default "Field value should be from list of ";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

    String propName();

    String[] values();

    class Validator implements ConstraintValidator<ValuesAllowed, String> {
        private String propName;
        private String message;
        private List<String> allowable;

        @Override
        public void initialize(ValuesAllowed requiredIfChecked) {
            this.propName = requiredIfChecked.propName();
            this.message = requiredIfChecked.message();
            this.allowable = Arrays.asList(requiredIfChecked.values());
        }

        public boolean isValid(String value, ConstraintValidatorContext context) {
            Boolean valid = value == null || this.allowable.contains(value);

            if (!valid) {
                context.disableDefaultConstraintViolation();
                context.buildConstraintViolationWithTemplate(message.concat(this.allowable.toString()))
                        .addPropertyNode(this.propName).addConstraintViolation();
            }
            return valid;
        }
    }
}

Mohock

Your code worked fine . But how do I make this ValuesAllowed validator reusable , Right now the array of allowed values is hardcoded in the class , Can you please edit your answer to make the code reusable for validating any field. – Schilt

I have edited the answer to pass the values through the controller. Usually, you can pass the list of values from the Controller or annotate the fields if you are using Request Bean. – Mohock

After adding the valuesallowed annotation, the request param became required parameter , How do I make it optional . – Schilt

AFAIK, the @RequestParam and Validator are working separately here. To make it an optional, we could return true in the validator when we pass in null for the value. Code - Boolean valid = value == null || this.allowable.contains(value); By doing this, when we don’t pass a value, it would not throw an exception. – Mohock

@Mohock in my controller i am using @Validated still my annotion is not triggered. cay you help. i am doing validation for multipart object – Izabel

@Izabel could you post your code so that i can take a look? – Mohock

Answer 2

You would have to change few things for this validation to work.

Controller should be annotated with @Validated and @ValuesAllowed should annotate the target parameter in method.

import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@Validated
@RestController
@RequestMapping("/api/opportunity")
public class OpportunityController {

    @GetMapping("/vendors/list")
    public String getVendorpage(
            @RequestParam(required = false)
            @ValuesAllowed(values = {
                    "OpportunityCount",
                    "OpportunityPublishedCount",
                    "ApplicationCount",
                    "ApplicationsApprovedCount"
            }) String orderBy,
            @RequestParam(required = false) String term,
            @RequestParam(required = false) Integer page, @RequestParam(required = false) Integer size,
            @RequestParam(required = false) String sortDir) {
        return "OK";
    }
}

@ValuesAllowed should target ElementType.PARAMETER and in this case you no longer need propName property because Spring will validate the desired param.

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {ValuesAllowedValidator.class})
public @interface ValuesAllowed {

    String message() default "Field value should be from list of ";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};

    String[] values();
}

Validator:

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.Arrays;
import java.util.List;

public class ValuesAllowedValidator implements ConstraintValidator<ValuesAllowed, String> {

    private List<String> expectedValues;
    private String returnMessage;

    @Override
    public void initialize(ValuesAllowed requiredIfChecked) {
        expectedValues = Arrays.asList(requiredIfChecked.values());
        returnMessage = requiredIfChecked.message().concat(expectedValues.toString());
    }

    @Override
    public boolean isValid(String testValue, ConstraintValidatorContext context) {
        boolean valid = expectedValues.contains(testValue);

        if (!valid) {
            context.disableDefaultConstraintViolation();
            context.buildConstraintViolationWithTemplate(returnMessage)
                    .addConstraintViolation();
        }
        return valid;
    }
}

But the code above returns HTTP 500 and pollutes logs with ugly stacktrace. To avoid it, you can put such @ExceptionHandler method in controller body (so it will be scoped only to this controller) and you gain control over HTTP status:

@ExceptionHandler(ConstraintViolationException.class)
@ResponseStatus(HttpStatus.BAD_REQUEST)
String handleConstraintViolationException(ConstraintViolationException e) {
    return "Validation error: " + e.getMessage();
}

... or you can put this method to the separate @ControllerAdvice class and have even more control over this validation like using it across all the controllers or only desired ones.

Minyan

How can i make sure the ValuesAllowed can use equalsIgnorecase in case client want to pass value wither in all Caps or CamelCase? – Contumacy

@TarunPande in ValuesAllowedValidator#initialize you need to map each of requiredIfChecked.values() to lower case and in ValuesAllowedValidator#isValid do the same while checking list contents. I would also add boolean ignoreCase field to ValuesAllowed interface so it's clear. – Minyan

Answer 3

I found that I was missing this dependency after doing everything else. Regular validation steps were working but the custom validators didn't work until I added this to my pom.

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

Seasickness