If you are willing to add user defined header without replacing the special chars from header line then
Use ExecuteStreamCommand processor with the below configs
in this processor we are routing all the lines except the first line i.e we are having the flowfile without header,
then use ReplaceText processor with Prepend as replacement Strategy to add your user defined header to the file.
Search Value
(?s)(^.*$)
Replacement Value
<user-defined-header>
Character Set
UTF-8
Maximum Buffer Size
1 MB //change the value as per your flowfile size
Replacement Strategy
Prepend
Evaluation Mode
Entire text
By using this method we are not going to have the header line from the file then we are adding the header to the flowfile content by using Replace Text processor.
(or)
instead of using ExecuteStreamCommand processor Use Record Oriented processors(like ConvertRecord) also we can do achieve this case.
Configure/enable csvreader/csvsetwriter as controller services to read the flowfile content and change the Include Header Line value to false in csv setwrtier controller service.
Then use ReplaceText processor to prepend the header by using this method also we need to define header in the replace text processor.
If you are willing to add user defined header without replacing the special chars from header line then
Use ExecuteStreamCommand processor with the below configs
in this processor we are routing all the lines except the first line i.e we are having the flowfile without header,
then use ReplaceText processor with Prepend as replacement Strategy to add your user defined header to the file.
Search Value
(?s)(^.*$)
Replacement Value
<user-defined-header>
Character Set
UTF-8
Maximum Buffer Size
1 MB //change the value as per your flowfile size
Replacement Strategy
Prepend
Evaluation Mode
Entire text
By using this method we are not going to have the header line from the file then we are adding the header to the flowfile content by using Replace Text processor.
(or)
instead of using ExecuteStreamCommand processor Use Record Oriented processors(like ConvertRecord) also we can do achieve this case.
Configure/enable csvreader/csvsetwriter as controller services to read the flowfile content and change the Include Header Line value to false in csv setwrtier controller service.
Then use ReplaceText processor to prepend the header by using this method also we need to define header in the replace text processor.
if you want to replace the special characters in header line then look into the below flow.
Flow:
So we are splitting the file as line count 1 in SplitText processor.
RouteOnAttribute Configs:
non_header
${fragment.index:gt(1)} //fragment index 1 is the header line.Use non_header relationship to feed MergeContent processor.
Feed the unmatched relationship to feed replace text processor, now unmatched relationship gets only the fragment.index = 1 flowfile i.e our header is in the flowfile content.
Use Replace text processor:
Now apply your logic to replace the special characters in the flowfile content.
Then feed the success relationship to Merge Content processor.
MergeContent processor Configs:
in mergecontent processor use Defragment as MergeStrategy so this processor will wait for all the fragments then does the merge.
Change the Delimiter Strategy to Text and Demarcator to shift+enter.
By following this method we are going to replace only the header line content and wait for all fragments and merge the contents of flowfile.
Reference flow.xml replace-header.xml
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Try with this approach once
In this flow we are forking once the file is pulled and on right side we are going to have all the contents without header
on Left side we are doing head -1 on the flowfile content to get only the header then by using replace text we are going to replacing the special characters.
In Both UpdateAttribute processors we are going to add GroupIdentifier and Order Attribute, so that are going to use these attributes in Enforce Order processor.
By using EnforceOrder Processor we are waiting for header flowfile(left side) to reach first then only we are going to process without header flowfile(right side).
Then change the success queue configurations of EnforceOrder processor prioritizers as FirstInFirstOutPrioritizer .
By using MergeContent Processor to merge the header with the flowfile content.
