在JSON对象中强制执行非空字段 [英] Enforce not-null field in JSON object

问题描述

我们的REST API接收一些JSON对象输入，其中某些字段必须不为null。那些可以是String / Integer，甚至可能是其他类实例作为参考。

Our REST API recieves some JSON objects input where some fields are required to be not null. Those can be either String/Integer or even might be some other class instance as reference.

我们试图找到一种方法来强制那些字段不为null，而是在api中进行空检查的正确方法。
当前：

We are trying to find a way to enforce those field to be not null, instead of the corrent way for null check in the api. Current:

    if (myObject.getSomeOtherObject() == null)
    throw new SomeException();

我们想要的是：

    class MyObject{
    @Required
    OtherObject someOtherObject;
    ...
    }

我们尝试了3件事：

• 升级到jackson 2.0.6并使用注释
  com.fasterxml.jackson.annotation.JsonProperty
  但是，这只是看起来不工作
  找到这些参考资料：
  http://jira.codehaus.org/browse / JACKSON-767

扩展JsonDeserializer以检查null但问题是它甚至没有在空输入上执行。

Extending JsonDeserializer to check null but the problem is that it does not even executed on the null input.

    public class NotNullDeserializer<T> extends JsonDeserializer<T> {

        @Override
        public T deserialize(JsonParser jsonparser, DeserializationContext deserializationcontext) throws IOException, JsonProcessingException {

            ParameterizedType superClass = (ParameterizedType) getClass().getGenericSuperclass();
            Class type = (Class) superClass.getActualTypeArguments()[0];

            T t = jsonparser.readValueAs(type);

            if (t == null){
                String classNameField = type.getName();
                String field = jsonparser.getCurrentName();
                throw new WrongInputException("The field '"+field+"' of type '"+classNameField+"' should not be null.");
            }

            return t;
        }

    }

    public class NotNullAddressDeserializer extends NotNullDeserializer<Address> {

    }

    @JsonDeserialize(using=NotNullAddressDeserializer.class)
        Address to;

• 编写我们自己的@Required注释并尝试检查ResourceFilter，但似乎我无法从ContainerRequest获取实际对象，即使我们可以，也不确定如何在object.otherObject.someObject.fieldNotNullable



    private class Filter implements ResourceFilter, ContainerRequestFilter {

        private final ArrayList requiredParameters;

        protected Filter() {
            requiredParameters = null;
        }

        protected Filter(ArrayList requiredParameters) {
            this.requiredParameters = requiredParameters;
        }

        @Override
        public ContainerRequestFilter getRequestFilter() {
            return this;
        }

        @Override
        public ContainerResponseFilter getResponseFilter() {
            return null;
        }


        @Override
        public ContainerRequest filter(ContainerRequest request) {
            if (requiredParameters != null && requiredParameters.size() > 0) {
                MultivaluedMap params = request.getQueryParameters();
                params.putAll(request.getFormParameters());
                StringBuffer missingParams = new StringBuffer();
                for (String reqParam : requiredParameters) {
                    List paramValues = params.get(reqParam);
                    if (paramValues == null || paramValues != null && paramValues.size() == 0)
                        missingParams.append(reqParam + ",");
                }
                if (missingParams.length() > 0)
                    throw new WrongInputException("Required parameters are missing: " + missingParams);
            }
            return request;
        }
    }



任何帮助和见解表示赞赏。


Any help and insights appreciated.

推荐答案

JAX-RS很好地将反序列化从验证中分离出来，即杰克逊有按设计否机制强制值非null 等。相反，您可以使用BeanValidation：

JAX-RS separates quite nicely the deserialization from the validation, i.e. Jackson has by design no mechanism to enforce values to be non-null, etc. Instead, you can use BeanValidation for that:



1. 在提供范围内，向 javax.validation：validation-api 添加依赖项。


2. 将 javax.validation.constraints.NotNull 注释添加到您的字段中。


1. Add a dependency to javax.validation:validation-api in provided scope.
2. Add the javax.validation.constraints.NotNull annotation to your field.

有关详细信息，请转到这里。

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