java - 仅当其他字段为 false 时才验证字段

Question

假设我有一个 @ConfigurationProperties 类，它需要根据另一个字段的值验证一组字段。例如，SdkProperties 有一个 enabled 字段。仅当 enabled 为 true 时，才应验证其他字段。

Sdk属性

@Configuration
@ConfigurationProperties(...)
@Data
@Validated
public class SdkProperties
{
    private boolean enabled;

    @NotEmpty
    private String apiKey

    // ... etc.
}

仅当 enabled 为 true 时，才应验证 @NotEmpty 注释。

执行此操作的正确方法是什么？

我已经看到使用 @AssertTrue 和 isValid 函数来手动处理验证的示例。但我不想那样做。

我想知道使用验证组是否可行？

Answer 1

您可以编写自定义ConstraintValidator。

@Configuration
@ConfigurationProperties(prefix = "sdk")
@Validated
@NotEmptyWhenEnabled // <----- custom validation -----
@Data
class SdkProperties {

    private boolean enabled;
    private String apiKey;
}

@Constraint(validatedBy = {NotEmptyWhenEnabledValidator.class})
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@interface NotEmptyWhenEnabled {
    String message() default "SDK apiKey needed when SDK is enabled";

    Class[] groups() default {};

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

class NotEmptyWhenEnabledValidator implements ConstraintValidator<NotEmptyWhenEnabled,SdkProperties> {

    @Override
    public boolean isValid(SdkProperties sdkProperties, 
                           ConstraintValidatorContext constraintValidatorContext) {
        boolean enabled = sdkProperties.isEnabled();
        boolean empty = null == sdkProperties.getApiKey() || sdkProperties.getApiKey().isEmpty();
        return !enabled || (enabled && !empty);
    }
}

然后，当启用 SDK 但未提供 API key 时，您会在启动时收到一条不错的消息。

***************************
APPLICATION FAILED TO START
***************************

Description:

Binding to target org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under 'sdk' to so.demo.SdkProperties$$EnhancerBySpringCGLIB$$1ecd6003 failed:

    Reason: SDK apiKey needed when SDK is enabled


Action:

Update your application's configuration


Process finished with exit code 0

编辑

自 spring-boot-2.2.0.RELEASE(2019 年 10 月 16 日)起，您有另一个选择。您可以验证构造函数中的属性。

通过使用:不可变@ConfigurationProperties绑定(bind)

Configuration properties now support constructor-based binding, which allows a @ConfigurationProperties-annotated class to be immutable. Constructor-based binding can be enabled by annotating a @ConfigurationProperties class or one of its constructors with @ConstructorBinding. Annotations such as @DefaultValue and @DateTimeFormat can be used on constructor parameters that are provided by configuration property binding.

引用:boot-features-external-config-constructor-binding

所以在你的情况下......

@ConfigurationProperties(prefix = "sdk")
class SdkProperties {

    private boolean enabled;
    private String apiKey;

    @ConstructorBinding
    public SdkProperties(boolean enabled, String apiKey) {
        this.enabled = enabled;
        this.apiKey = apiKey;
        // direct validation in the constructor
        boolean apiKeyNullOrEmpty = null == apiKey || apiKey.isEmpty();
        Assert.isTrue(!enabled || !apiKeyNullOrEmpty, "When SDK is enabled, a SDK-api key is mandatory!");
    }

    public boolean isEnabled() {  return enabled; }
    public void setEnabled(boolean enabled) { this.enabled = enabled; }
    public String getApiKey() {return apiKey; }
    public void setApiKey(String apiKey) { this.apiKey = apiKey; }
}