[英]EvaluateJsonPath unable to return a scalar
I'm trying to extract a value from JSON to a flowfile-attribute . 我正在尝试从JSON提取一个值到flowfile-attribute 。 When I run the EvaluateJsonPath processor I get an error stating
当我运行EvaluateJsonPath处理器时,出现错误提示
"Unable to get a scalar value for expression $..fields.storyBoard.stringValue
. "Unable to get a scalar value for expression $..fields.storyBoard.stringValue
。
Input JSON looks like this: 输入JSON如下所示:
{
"name" : "projects/fakedims-0000/databases/(default)/documents/device/0000",
"fields" : {
"reportKey" : {
"stringValue" : "abc123"
},
"dateOccured" : {
"timestampValue" : "2018-10-14T04:00:00Z"
},
"storyBoard" : {
"stringValue" : "https://path/to/media"
},
"new" : {
"integerValue" : "25"
},
"name" : {
"stringValue" : "device one"
},
"location" : {
"geoPointValue" : {
"latitude" : -78.413751,
"longitude" : 38.156487
}
}
},
"createTime" : "2018-10-19T00:02:26.209335Z",
"updateTime" : "2018-10-19T22:22:24.382136Z"
}
The JSONPath expression is $..fields.storyBoard.stringValue
JSONPath表达式为
$..fields.storyBoard.stringValue
fields.storyBoard.stringValue
What I think is happening is that the processor is returning ["https://path/to/media"]
rather than just the string. 我认为正在发生的事情是处理器正在返回
["https://path/to/media"]
而不只是字符串。
This is what I get if a evaluate to flowfile-content rather than an attribute. 如果对flowfile-content而不是属性进行评估,这就是我得到的。 Why?
为什么? What can I do to fix it?
我该如何解决?
Change the Return Type property value to json in EvaluateJsonPath
processor, if you are extracting as flowfile-attribute 如果要提取为flowfile-attribute,则在
EvaluateJsonPath
处理器中将Return Type属性值更改为json 。
Return Type property description: 返回类型属性说明:
Indicates the desired return type of the JSON Path expressions.
指示所需的JSON Path表达式的返回类型。 Selecting ' auto-detect ' will set the return type to ' json ' for a Destination of ' flowfile-content ', and ' scalar ' for a Destination of ' flowfile-attribute '.
选择“ 自动检测 ”将针对“ flowfile-content ”的目的地将返回类型设置为“ json ”,对于“ flowfile-attribute ”的目的地将其返回类型设置为“ scalar ”。
As you are trying to extract nested key not the key on the root level(ex:name,createTime..), that's the reason why we need to configure the Return Type as Json not as scalar .
当您尝试提取嵌套键而不是根级别的键(例如:name,createTime ..)时,这就是为什么我们需要将返回类型配置为Json而不是标量的原因 。
In Addition you can use FlattenJson processor(seperator '_') to flatten-out all nested json then use Return Type as auto detect
in EvaluateJsonPath processor. 另外,您可以使用FlattenJson处理器(分隔符“ _”)将所有嵌套的json扁平化,然后在EvaluateJsonPath处理器中将
Return Type as auto detect
。
EvaluateJsonConfigs: EvaluateJsonConfigs:
Output: We are going to have attribute value without enclosing in an array 输出:我们将拥有属性值,而无需将其包含在数组中
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