Nifi Groovy script to modify csv rows giving MissingMethodException error

Question

I am working on a groovy script which will take following csv file as input

Id, Name, Class
1, Kevin,[Eight, Nine]
2, Mark,Four

and create or change csv as follows

Id, Name, Class
1, Kevin,Eight
1, Kevin,Nine
2, Mark,Four

Basically, If column Class has array of string then put it in multiple rows replicating all other column values.

def flowFile = session.get()
if(!flowFile) return
try {
flowFile = session.write(flowFile, {inputStream, outputStream ->
    outputStream.withWriter("UTF-8"){ w ->
        inputStream.eachLine("UTF-8"){ line ->
            def subString = line.takeBetween('[', ']')
            def splitArray = subString.split(',')
             if(splitArray.length > 1) {
                def lineBefore = line.takeBefore('[');
                def lineAfter = line.takeAfter(']');
                for(int i=0;i<splitArray.length;i++) {
                    w << lineBefore << row.getAt(i) << lineAfter << '\n'
                }
            }else {
                w << line << '\n'
            }
        }
    }
} as StreamCallback)

session.transfer(flowFile, REL_SUCCESS)
}catch(e) {
      log.error('Error capturing nextLink', e)
      session.transfer(flowFile, REL_FAILURE)
}

I am getting the below error:

 Error capturing nextLink: groovy.lang.MissingMethodException: No signature of method: java.lang.String.takeBetween() is applicable for argument types: (String, String) values: [[, ]]

But the method takeBetween in def subString = line.takeBetween("[", "]") is working perfectly fine in eclipse

Answer 1

The following groovy script with 'substring' method instead of 'takeBetween' helped me create the csv in required format

def flowFile = session.get()
if(!flowFile) return
try {
flowFile = session.write(flowFile, {inputStream, outputStream ->
    outputStream.withWriter("UTF-8"){ w ->
        inputStream.eachLine("UTF-8"){ line ->
         def splitArray = new String[0];
         def subString = "";
         def x = line.indexOf("[")+1;
         def y = line.indexOf("]");
         if(x > 0 && y >0)
         subString = line.substring(x,y);
         if(subString != null && subString.length() >0)
             splitArray = subString.split(',')
             if(splitArray.length > 1) {
                 def lineBefore = line.substring(0,x);
                 def lineAfter = line.substring(y,line.length());
                for(int i=0;i<splitArray.length;i++) {
                    w << lineBefore << splitArray.getAt(i) << lineAfter << '\n'
                }
            }else {
                w << line << '\n'
            }
        }
    }
} as StreamCallback)

session.transfer(flowFile, REL_SUCCESS)
}catch(e) {
      log.error('Error capturing nextLink', e)
      session.transfer(flowFile, REL_FAILURE)
}