英文:
JSON to POJO null check for fields
问题
我有一个非常大且复杂的JSON，我正在将其映射到一个简单的POJO（只包含所需的字段）。在Groovy中，JSON被解释为Map。
MyObject build(Map<String, Object> payload){
...
o.name = payload.a.b.name
o.gender = payload.c.d.e.gender
return o
}
这些字段是可选的，如果不存在会抛出NullPointerException。如何映射为空字符串""，而不是为每行都添加try-catch？可能很直接，但我想不出如何做。
英文:
I have a very large complex JSON and I'm mapping this to a simple POJO (with only the required fields). In groovy JSON is interpreted as Map.
MyObject build(Map<String, Object> payload){
...
o.name = payload.a.b.name
o.gender = payload.c.d.e.gender
return o
}
The fields are optional and throws NullPointerException when not present. How to map to "" without putting try-catch for each line? My be straight forward but can't figure out how.
答案1
得分: 0
将安全导航操作符和Elvis操作符结合起来使用。
如果在遍历payload时出现异常：
o.gender = payload.c.d.e.gender
将其更改为：
o.gender = payload?.c?.d?.e?.gender ?: Gender.UNSET
（如果允许null，则可以省略?:...部分）
英文:
You would combine the safe navigation operator and the elvis operator.
If this throws while walking down the payload:
o.gender = payload.c.d.e.gender
Change it to:
o.gender = payload?.c?.d?.e?.gender ?: Gender.UNSET
(or if a null is fine, then leave out the ?:... part)
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