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Thread: JSON Input step for Mongodb - MySQL

  1. #1
    Join Date
    Feb 2011
    Posts
    16

    Default JSON Input step for Mongodb - MySQL

    Hi,

    I am using the PDI Version pdi-ce-4.2.0-M1

    I was trying to get values from Mongodb using Mongodb input step. I was able to get the JSON output values (string). Now I need to push the mongodb output data to a mysql database. I read the article saying that the JSON output strings must be passed to "JSON Input Step" for the further processing. http://www.ibridge.be/?p=196

    I took a new step "JSON INput" and the hop was given between Mongodb Input ---> JSON Input.

    In the field tab of JSON Input, I have enabled "Source is defined in the field" .I wanted the Output JSON string of Mongodb Input to be passed to JSON Input step.

    After enabling "Source is defined in the field" option,I was not able to do "preview rows operation". I dont see any document related to JSON Input. which means that data was not passing to the JSON Input from Mongodb Input

    The error log says

    build 15030 from 2011-04-13 17.23.00 by tomcat) : No field specified! Stop processing.
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : Unexpected Error : org.pentaho.di.core.exception.KettleException:
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : No field specified! Stop processing.
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : org.pentaho.di.core.exception.KettleException:
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : No field specified! Stop processing.
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) :
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : at org.pentaho.di.trans.steps.jsoninput.JsonInput.ReadNextString(JsonInput.java:127)
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : at org.pentaho.di.trans.steps.jsoninput.JsonInput.getOneRow(JsonInput.java:388)
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : at org.pentaho.di.trans.steps.jsoninput.JsonInput.processRow(JsonInput.java:338)
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : at org.pentaho.di.trans.step.RunThread.run(RunThread.java:40)
    2011/05/14 16:49:28 - Json Input.0 - ERROR (version 4.2.0-M1, build 15030 from 2011-04-13 17.23.00 by tomcat) : at java.lang.Thread.run(Thread.java:662)
    2011/05/14 16:49:28 - Json Input.0 - Signaling 'output done' to 0 output rowsets.

    Transformation verification error output

    Stepname Result Remark
    Json Input 4 - Error No field to extract





    How do I specify the fields in JSON Input?? What am I doing wrong here??

    Is there any way around I could move the data from mongodb to mysql?


    thanks in advance

  2. #2

    Default

    Hi

    Did you specified fields returned from JSON Input step?
    The error "No field specified!" say that you did not :-)

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  3. #3
    Join Date
    Feb 2011
    Posts
    16

    Default

    Thanks for the reply.

    I provided the output fields. The data is not sent from mongodb input step (JSon output structures) to JSON Input. I understand that mongodb output would be JSON strings, and i am trying to parse the JSON string to the JSON Input step. Do you see any documentation available for using JSON Input step.

    I just want to know how to use JSON Input step

    Thanks in advance

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