How to provide filenames dynamically in NIFI?

[#1]

Hi Team,

I have a zipped file which contains so many text files. I used unpackContent processor to unzip the files. I want to store those unzipped files in another location. But the file names should be replaced with file1.txt, file2.txt, file3.txt and so on. How can I give file names dynamically? I thought updateAttribute can be used in this. But I'm not sure at the expression language to get this done. Can anyone help me to write a expression language in updateAttribute processor or any alternative processor/solution for this.

Thanks.

[#2 · Accepted solution]

Hello @girish6,

NiFi Expression language does have a function that will increment a number, but it does not reset back to zero (unless you restart NiFi) and is incremented globally across call calls to that function.

So while this function will give each FlowFile a unique filename per NiFi node, there is no guarantee that they will be sequential or will start at 0 for new source zip file you extract.  If this works for your use case the NiFi Expression language statement would look like this in the UpdateAttribute processor:


If you are just looking for filename uniqueness, a better solution may be to instead append the FlowFile's uniquely assigned UUID to the filename instead as follows:

Tips: 
1. There is an expression language guide in the embedded help of your NiFi installation found by clicking on the global menu icon in upper right corner.
2. Within a NiFi processor property that support NiFi EL you can display a list of functions with details by typing "${" (signifies start of an EL statement) and then hold "Control" while clicking space bar.  This also works if you are mid statement and type ":"then "control" + click spacebar.

Examples:
file-${   (then cntrl+spacebar)
${uuid:  (then cntrl+spacebar)

Hope this helps,
Matt