英文:
Default JSON property if not exists using Jolt
问题
我想要设置一个默认值，只有在 JSON 属性不存在时才生效。
例如，以下是我的 Jolt 规范：
[
{
"operation": "modify-default-beta",
"spec": {
"lastName": "[empty]"
}
},
{
"operation": "shift",
"spec": {
"firstName": "firstName",
"lastName": "lastName"
}
}
]
当输入为：
{
"firstName": "John"
}
输出如下所示：
{
"firstName" : "John",
"lastName" : "[empty]"
}
另一方面，当输入为：
{
"firstName": "John",
"lastName": null
}
我期望输出与输入相同：
{
"firstName": "John",
"lastName": null
}
是否有一种方法只在属性不存在时设置默认值，而不考虑其值。谢谢。
英文:
I want to set a default value only if the JSON property not exists.
For example, below is my Jolt spec :
[
{
"operation": "modify-default-beta",
"spec": {
"lastName": "[empty]"
}
},
{
"operation": "shift",
"spec": {
"firstName": "firstName",
"lastName": "lastName"
}
}
]
When input is :
{
"firstName": "John"
}
the output is as expected :
{
"firstName" : "John",
"lastName" : "[empty]"
}
On the other hand when input is :
{
"firstName": "John",
"lastName": null
}
I'm expecting the output is same as the input :
{
"firstName": "John",
"lastName": null
}
is there anyway to default only when property not exists regardless of it value. Thanks
答案1
得分: 2
首先，shift转换是不必要的。您可以在修改转换中使用isNull函数，例如：
[
{
"operation": "modify-default-beta",
"spec": {
"lastName": ["=isNull(@(1,&))", "[empty]"]
}
}
]
其中：
@(1,&)表示当前属性的值，例如"lastName"（ampersand代表lastName文字）- 如果函数能够运行，则直接返回值
null，
否则返回第二个参数"[empty]"。
英文:
First of all the shift transformation is not needed. You can use an isNull function within a modify transformation such as
[
{
"operation": "modify-default-beta",
"spec": {
"lastName": ["=isNull(@(1,&))", "[empty]"]
}
}
]
where
@(1,&)represents the value of the current attribute, eg.
"lastName"(the ampersand stnds for thelastNameliteral)- if the function is able to run, then the value
nullreturns directly,
otherwise the second argument"[empty]"returns
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