如何不在杰克逊发送空集合 [英] How to not send an empty collection in jackson

问题描述

我有一个被强制序列化的对象：

I have an object that is curently being serialized to:

{
  "label" : "label",
  "proxyIds" : [ ],
  "childIds" : [ 161, 204, 206, 303, 311 ],
  "actionIds" : [ 157, 202 ],
}

该proxyIds是java对象中的空（非空）集合。

That proxyIds is an empty (not null) collection in the java object.

如何配置Jackson根本不在json中包含该对象？

How do I configure Jackson to not include that object in the json at all?

我希望行为类似于xml / soap中的unwrapped集合，如果集合为空，则不包括在内。我不需要区分null和empty集合，并希望减小json有效负载的大小。

I want behaviour similar to "unwrapped" collections in xml/soap where if the collection is empty it is not included. I do not need to distinguish between null and empty collection and want to reduce the size of the json payload.

推荐答案

这可能是很长一段时间但是如何使用Inclusions和定义NON_DEFAULT作为包含属性。文档说：

This may be a long shot but how about using Inclusions and defining NON_DEFAULT as the inclusion property. The docs say:

值，表示只有值与默认设置不同的属性（表示使用无参数构造函数构造Bean时的值）将被包括在内。

"Value that indicates that only properties that have values that differ from default settings (meaning values they have when Bean is constructed with its no-arguments constructor) are to be included."

因此，如果默认值为空数组，则应跳过它。

So if the default value is an empty array it should skip it.

类似于：

ObjectMapper mapper = new ObjectMapper();
mapper.getSerializationConfig().setSerializationInclusion(Inclusion.NON_DEFAULT);


public class Test {
     String[] array = { };
     ....
}

http://jackson.codehaus.org/1.1.2/javadoc/org/codehaus/ jackson / map / annotate / JsonSerialize.Inclusion.html

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