I am using EvaluateJsonPath to extract one particular value from JSON. I am using the follwoing JSONPath expression:
$.data[?(@.containerType == 'SOURCE' && @.path == 'SOURCE_KYLO_DATALAKE')].id
This is the JSON document I'm calling the JSONPath on :
{"data":[{"id":"dc18bf87-c5a6-4600-9584-e79fb988b1d0","path":["@Rakesh.Prasad@diageo.com"],"tag":"0","type":"CONTAINER","containerType":"HOME"},{"id":"42e52055-4deb-4d5d-942f-4e1c4e48c35e","path":["BPM"],"tag":"3","type":"CONTAINER","containerType":"SPACE"},{"id":"49e3d118-e4f9-41ef-ad97-6b2745c75c4f","path":["DATABRICKS_USAGE_REPORT"],"tag":"0","type":"CONTAINER","containerType":"SPACE"},{"id":"613f52e9-64df-4c9c-b083-c282f349eb4e","path":["LIGHTHOUSE"],"tag":"3","type":"CONTAINER","containerType":"SPACE"},{"id":"f57bcd83-4d0e-481e-b880-0fb8b20798a1","path":["MDM"],"tag":"2","type":"CONTAINER","containerType":"SPACE"},{"id":"745cd2d5-7303-4c0a-9cab-f5205b9eec90","path":["NIELSEN"],"tag":"2","type":"CONTAINER","containerType":"SPACE"},{"id":"b40da338-c429-4bb3-b2ef-51295a143fc8","path":["PowerBI"],"tag":"0","type":"CONTAINER","containerType":"SPACE"},{"id":"dffd025c-b0f0-4b9b-9060-da4aa54204d1","path":["REFERENCE_DATA"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"14f9759a-2059-4728-acad-fe01f129f148","path":["SAP_ODP_MASTERDATA"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"063bb5e8-041a-4f69-98a3-d2509d5e89d0","path":["TRAX"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"9c737147-6632-4328-bf10-ba4959a2806f","path":["TRAX_API"],"tag":"0","type":"CONTAINER","containerType":"SPACE"},{"id":"99167858-17ca-406f-b887-62af3d0da68a","path":["DEPLETION"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"52f17de1-a66e-4f08-9077-04acf3914663","path":["SOURCE_ADLS_NIELSEN_PROD"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"bea0de9c-b579-46bd-89ff-4b9497c3910e","path":["SOURCE_KYLO_DATALAKE"],"tag":"5","type":"CONTAINER","containerType":"SOURCE"},{"id":"20985e83-cd31-469e-9a17-1e586bccfb27","path":["SOURCE_LIGHTHOUSE_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"47406901-c9ce-4fce-b0ab-37b07338949b","path":["SOURCE_MDM_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"f1feff7d-8ada-46bb-a5fe-0283a2c746b3","path":["SOURCE_MDS_UAT"],"tag":"0","type":"CONTAINER","containerType":"SOURCE"},{"id":"48a5d1b6-8d32-449d-a317-d242f2394e71","path":["SOURCE_NIELSEN_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"32eaeeb5-60d5-4d87-a983-1e71e3543920","path":["SOURCE_PROD_BPM"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"f4af00a5-a536-4272-93cb-891ec13ef8e4","path":["SOURCE_SAP_MDS_STAGING"],"tag":"3","type":"CONTAINER","containerType":"SOURCE"},{"id":"7250d605-75a9-4ef2-a01b-55c2bcb44dd9","path":["SOURCE_TRAX_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"38a8293e-72f4-42c2-be66-667b21a1ac55","path":["SOURCE_KYLO_HIVE2"],"tag":"10","type":"CONTAINER","containerType":"SOURCE"},{"id":"95cb9f2f-3421-451a-8635-bb8487dc1872","path":["dwlprd1"],"tag":"7","type":"CONTAINER","containerType":"SOURCE"},{"id":"ac9334e4-daf2-4c6f-92f1-0452440fb737","path":["dwlprd2"],"tag":"5","type":"CONTAINER","containerType":"SOURCE"},{"id":"c27af9bd-075b-4fb8-bcd4-8450f26ff7f9","path":["SOURCE_ADLS_NIELSEN_DEPLETION_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"}]}
When I use the configuration(that specific JSONPath query) from above on a JSONPath online testing tool (see attached image), I get the expected result. But somehow nifi is returning empty array.
Template:
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FlowFiles</key><value>false</value></entry><entry><key>generate-ff-custom-text</key><value>{"data":[{"id":"dc18bf87-c5a6-4600-9584-e79fb988b1d0","path":["@Rakesh.Prasad@diageo.com"],"tag":"0","type":"CONTAINER","containerType":"HOME"},{"id":"42e52055-4deb-4d5d-942f-4e1c4e48c35e","path":["BPM"],"tag":"3","type":"CONTAINER","containerType":"SPACE"},{"id":"49e3d118-e4f9-41ef-ad97-6b2745c75c4f","path":["DATABRICKS_USAGE_REPORT"],"tag":"0","type":"CONTAINER","containerType":"SPACE"},{"id":"613f52e9-64df-4c9c-b083-c282f349eb4e","path":["LIGHTHOUSE"],"tag":"3","type":"CONTAINER","containerType":"SPACE"},{"id":"f57bcd83-4d0e-481e-b880-0fb8b20798a1","path":["MDM"],"tag":"2","type":"CONTAINER","containerType":"SPACE"},{"id":"745cd2d5-7303-4c0a-9cab-f5205b9eec90","path":["NIELSEN"],"tag":"2","type":"CONTAINER","containerType":"SPACE"},{"id":"b40da338-c429-4bb3-b2ef-51295a143fc8","path":["PowerBI"],"tag":"0","type":"CONTAINER","containerType":"SPACE"},{"id":"dffd025c-b0f0-4b9b-9060-da4aa54204d1","path":["REFERENCE_DATA"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"14f9759a-2059-4728-acad-fe01f129f148","path":["SAP_ODP_MASTERDATA"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"063bb5e8-041a-4f69-98a3-d2509d5e89d0","path":["TRAX"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"9c737147-6632-4328-bf10-ba4959a2806f","path":["TRAX_API"],"tag":"0","type":"CONTAINER","containerType":"SPACE"},{"id":"99167858-17ca-406f-b887-62af3d0da68a","path":["DEPLETION"],"tag":"1","type":"CONTAINER","containerType":"SPACE"},{"id":"52f17de1-a66e-4f08-9077-04acf3914663","path":["SOURCE_ADLS_NIELSEN_PROD"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"bea0de9c-b579-46bd-89ff-4b9497c3910e","path":["SOURCE_KYLO_DATALAKE"],"tag":"5","type":"CONTAINER","containerType":"SOURCE"},{"id":"20985e83-cd31-469e-9a17-1e586bccfb27","path":["SOURCE_LIGHTHOUSE_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"47406901-c9ce-4fce-b0ab-37b07338949b","path":["SOURCE_MDM_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"f1feff7d-8ada-46bb-a5fe-0283a2c746b3","path":["SOURCE_MDS_UAT"],"tag":"0","type":"CONTAINER","containerType":"SOURCE"},{"id":"48a5d1b6-8d32-449d-a317-d242f2394e71","path":["SOURCE_NIELSEN_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"32eaeeb5-60d5-4d87-a983-1e71e3543920","path":["SOURCE_PROD_BPM"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"f4af00a5-a536-4272-93cb-891ec13ef8e4","path":["SOURCE_SAP_MDS_STAGING"],"tag":"3","type":"CONTAINER","containerType":"SOURCE"},{"id":"7250d605-75a9-4ef2-a01b-55c2bcb44dd9","path":["SOURCE_TRAX_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"},{"id":"38a8293e-72f4-42c2-be66-667b21a1ac55","path":["SOURCE_KYLO_HIVE2"],"tag":"10","type":"CONTAINER","containerType":"SOURCE"},{"id":"95cb9f2f-3421-451a-8635-bb8487dc1872","path":["dwlprd1"],"tag":"7","type":"CONTAINER","containerType":"SOURCE"},{"id":"ac9334e4-daf2-4c6f-92f1-0452440fb737","path":["dwlprd2"],"tag":"5","type":"CONTAINER","containerType":"SOURCE"},{"id":"c27af9bd-075b-4fb8-bcd4-8450f26ff7f9","path":["SOURCE_ADLS_NIELSEN_DEPLETION_UAT"],"tag":"1","type":"CONTAINER","containerType":"SOURCE"}]}</value></entry><entry><key>character-set</key><value>UTF-8</value></entry></properties><runDurationMillis>0</runDurationMillis><schedulingPeriod>1 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sec</yieldDuration></config><name>EvaluateJsonPath</name><relationships><autoTerminate>false</autoTerminate><name>failure</name></relationships><relationships><autoTerminate>false</autoTerminate><name>matched</name></relationships><relationships><autoTerminate>false</autoTerminate><name>unmatched</name></relationships><state>STOPPED</state><style/><type>org.apache.nifi.processors.standard.EvaluateJsonPath</type></processors></snippet><timestamp>09/24/2018 06:03:42 EDT</timestamp></template>
As you are searching for value in path array, Enclose SOURCE_KYLO_DATALAKE in [](array) then processor will only result the matching id value as output content.
Change the Eval JsonPath property value as below
dataset
$.data[?(@.containerType == 'SOURCE' && @.path == ['SOURCE_KYLO_DATALAKE'])].id
Configs:
Output Flowfile Content:
["bea0de9c-b579-46bd-89ff-4b9497c3910e"]
UPDATE:
I have used NiFi-1.7.1 and EvaluateJson expression works fine in this version.
However if you are using other versions of NiFi then
1.if you are having only one element in array then use below expression in your EvaluateJsonPath processor.
dataset
$.data[?(@.containerType == 'SOURCE' && @.path[0] == 'SOURCE_KYLO_DATALAKE')].id
2.If you are having more than one element in array then
Flow:
Flow Description:
1.SplitJson
- to split data array into individual messages
- configure JsonPathExpression to
$.data
2.EvaluateJsonPath
- To extract required content and keep as attribute to the flowfile
Now we are having id,containerType,path values as attributes to the flowfile
3.RouteOnAttribute:
in this processor we are checking the attribute values using NiFi expression language
Add new property as
required
${containerType:equals("SOURCE"):and(${anyDelineatedValue("${path:replace('[',''):replace(']','')}",","):equals('"SOURCE_KYLO_DATALAKE"')})}
Feed the required relationship to ReplaceText processor
4.ReplaceText
- Now we are replacing the id values to the flowfile content
Now we are going to have the id value in your output flowfile content from ReplaceText processor.
If possible upgrade the NiFi version to 1.7.1 then you don't need to do all these workarounds :)
来源：https://stackoverflow.com/questions/52477093/nifi-processor-is-not-parsing-json-correctly