Loading multiple csv files and text process

Hi Community!

I am a newbie to Knime and would appreciate you guidance with the following matter as I have not been able to find an answer online.

I am looking to read in multiple csv files from a folder (all files in a particular folder) and so I have used the 'List Files' node. The node creates a list of the files in the folder but I can't find the proper node or configuration to use the 'Strings to Document' and 'Bag of Words Creator' nodes to begin the text processing. I tried different nodes to load in the content of the files from the 'List' but to no avail. 

When I process one csv files the process is simply - 'CSV Reader' -> 'Strings to Document' -> ' Bag of Words' and then other filters.

How can I go about reading in multiple files and then text process them? 

Thanks in advance


Hi Ofer,

in the MetaNodes Category, there is a Iterate List of Files Node. Provide it with the input of the list files node and it will read the files.

If you want to include the preprocesing, open the meta node and make your preprocessing between the file reader and the Loop End node.

Best, Iris

Hi Ofer,
To read from multiple csv file you have to:

  1. List files using “List Files” node,
  2. Pass file list to “Table Row To Variable Loop Start” node
  3. Pass file list as a variable to “File Reader” node - using flow variable point- first you have to configure this node to read file with desire structure. Next on Flow Variables page have to in position “DataURL” choose “URL”
  4. End loop with “Loop end” node
    After that you shall have table with data from all csv files from folder

I hope this will help


Hi Piotr,

I have constructed the workflow you have defined above and I am getting stuck on the "Dataurl:url" flow variable setting. I keep getting the error, "The 'DataURL' parameter is controlled by a variable and I cannot proceed.

Are you able to help troublshoot this?

Thanks, Pash

You must execute the Loop Start node, then it should work.


Hi Iris,

This is just perfect! Thanks a million :)

All the best,



Someone can help me...

I made all this procedure but they give me this error message:

"WARN  CSV Writer           0:4        Input table must only contain String, Int, or Doubles"

See attach... pls...


Hi Zealicio,

and what is the data you are writing? Can you post the data table spec?