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  1. Zeppelin
  2. ZEPPELIN-5482

Run paragraph from another using z.run() throws a null pointer exception




      I am having a few issues with Apache Zeppelin, specifically how to invoke a paragraph from another. I am using Zeppelin Version 0.9.0 with the Python interpreter.

      The aim of what I am trying to achieve is to have some paragraph with a drop down of dates, and when the user selects a date, I want to run some other paragraphs. This is so that the user does not need to select a date in every single paragraph. With the date, I will locate some files and present them in tables/charts.

      Looking at the documentation, it suggests we can use z.run() with the given note id and paragraph id. Unfortunately when I do this, I keep getting an error.

      Here is a minimum example of what I am trying:

      # Cell 1 - Create select box, allow user selection, then trigger Cell 2 user_choice = z.select("f2", [("o1","1"), ("o2","2")], "o1") z.run('2GBQ57B2K', 'paragraph_1627463517803_1716289354')


      # Cell 2 - Triggered as user made a choice in Cell 1.

      This results in an error in Cell 1. Please see the log below:


      Py4JJavaError: An error occurred while calling o1.run.
      : java.lang.NullPointerException
          at org.apache.zeppelin.interpreter.ZeppelinContext.run(ZeppelinContext.java:497)
          at org.apache.zeppelin.interpreter.ZeppelinContext.run(ZeppelinContext.java:475)
          at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
          at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
          at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
          at java.lang.reflect.Method.invoke(Method.java:497)
          at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
          at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
          at py4j.Gateway.invoke(Gateway.java:282)
          at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
          at py4j.commands.CallCommand.execute(CallCommand.java:79)
          at py4j.GatewayConnection.run(GatewayConnection.java:238)
          at java.lang.Thread.run(Thread.java:745)
      (<class 'py4j.protocol.Py4JJavaError'>, Py4JJavaError('An error occurred while calling o1.run.\n', JavaObject id=o24), <traceback object at 0x7facaea7d7c8>)


      Has anyone encountered this before? Or any thoughts on what could be going wrong? I have not been able to find anything online. For what it's worth, z.runNote() works but it runs everything. I hope to only run a subset of paragraphs ids.

      Many thanks





            Unassigned Unassigned
            lakhvirss Lakhvir Singh Sohal
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