Nifi: how to remove session based on atribute value in nifi

[#1]

I want to remove session in case i get certain data from file i have code like this,but i got errors "flowfile has already marked for removal", what should i change to get rid of extra errors? In case of session rollback flowfile will dissapear in queues also? 2.should i use rollback instead of remove()? NodeList childNodes = nodeGettingChanged.getChildNodes();for(int i =0; i != childNodes.getLength();++i){Node child = childNodes.item(i);if(!(child instanceofElement))continue;if(child.getNodeName().equals("runAs")){if(child.getFirstChild().getTextContent()=="false"){ session.remove(flowFile1);File deleteExtraFile =newFile("C://Users//s.tkhilaishvili//Desktop//try2//nifi-1.3.0//1//conf.xml");booleandelete=deleteExtraFile.delete();}else{ child.getFirstChild().setNodeValue("false");}}} Document finalXmlDocument = xmlDocument; session.write(flowFile1, new StreamCallback() { publicvoid process(InputStream inputStream,OutputStream outputStream)throwsIOException{TransformerFactory transformerFactory =TransformerFactory.newInstance();Transformer transformer =null;try{ transformer = transformerFactory.newTransformer();}catch(TransformerConfigurationException e){ e.printStackTrace();}DOMSource source =newDOMSource(finalXmlDocument); ffStream.close();ByteArrayOutputStream bos =newByteArrayOutputStream();StreamResult result =newStreamResult(bos);try{ transformer.transform(source, result);}catch(TransformerException e){ e.printStackTrace();}byte[] array = bos.toByteArray(); outputStream.write(array);}}); session.remove(flowFile); session.transfer(flowFile1, REL_SUCCESS);}

[#2]

It's hard to tell from the formatting of your code above, but if you are executing session.remove(flowFile1) then later trying to transfer it to REL_SUCCESS, you will get that error. You can either change the logic to put the remove/transfer calls into an if-else block, or keep a boolean variable indicating whether the flow file has already been removed, and transfer if it has not been removed. It looks like you already have an if-clause checking the firstChild for "false", perhaps you could put the transfer in an else-clause.

[#3]

@mburgess I have the same problem. The code was written in jython.

from org.apache.commons.io import IOUtils

from java.nio.charset import StandardCharsets

from org.apache.nifi.processor.io import OutputStreamCallback

from java.lang import Object

# Define a subclass of OutputStreamCallback for use in session.write()

class PyOutputStreamCallback(OutputStreamCallback):

  def __init__(self, cadena):

    self.cadena = cadena

  def process(self, outputStream):

    outputStream.write(bytearray(self.cadena.encode('utf-8')))

# end class

flowFile = session.get()

if (flowFile != None):

    table = flowFile.getAttribute('table_name')

    if (table != 'database_1.dbo.dtproperties'):

        newFlowFile = session.create(flowFile)

        newFFC = ''

        newFlowFile = session.write(newFlowFile, PyOutputStreamCallback(newFFC))        

        session.transfer(newFlowFile, REL_SUCCESS)

    elif (table == 'database_1.dbo.dtproperties'):

        session.remove(flowFile)

    else:

        session.transfer(flowFile, REL_FAILURE)

I'm understanding that flow files are passing one by one, right? So if there is a flow file with an attribute ''database_1.dbo.dtproperties" should be eliminated without affecting other flow files. But I got "flowfile has already marked for removal"