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[英]Apache NiFi JoltTransformJSON processor attribute as jolt spec
[英]Apache Nifi JOLTTransformJSON Processor
我有一個流程旨在使用Get twitter處理器提取推文,並且我使用JOLTTransformJSON處理器提取一些屬性,包括井號,我的Jolt規范如下
[
{
"operation": "shift",
"spec": {
"entities": {
"hashtags": {
"*": "hashtags"
}
},
"text": "content",
"id": "id",
"timestamp_ms": "timestamp",
"retweet_count": "retweetcount",
"url": "url"
}
},
{
"operation": "default",
"spec": {
"type": "twitter"
}
},
{
"operation": "cardinality",
"spec": {
"hashtags": "MANY"
}
}
]
當twitter輸出包含主題標簽時,JOLTTransformJSON處理器輸出將通過以下方式為我提供這些主題標簽
{
"hashtags": [{
"text": "Venus",
"indices": [16,
22]
},
{
"text": "Cancer",
"indices": [69,
76]
},
{
"text": "ascendant",
"indices": [86,
96]
}],
"content": "acmc_clock_euro #Venus is now (16h58m01s UT) setting at 10°32'50.2'' #Cancer opposite #ascendant at Helsinki, SF",
"id": 895332436975931393,
"timestamp": "1502298862104",
"retweetcount": 0,
"url": "https://twitter.com/pe602/status/895332436975931393",
"type": "twitter"
}
但是,如果hashtags數組為空,則如下所示
"entities": {
"hashtags": []
輸出將不包含主題標簽,如果twitter op沒有使用JOLT處理器的主題標簽,如何使輸出具有主題標簽元素但具有空數組。
在第二個“默認”操作中嘗試此操作。
{
"operation": "default",
"spec": {
"hastags": [],
"type": "twitter"
}
}
通過使用“ modify-default-beta”操作來解決此問題,如下所示
{“ operation”:“ modify-default-beta”,“ spec”:{“ hashtags”:[]}}
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