ReplaceText

Description

Updates the content of a FlowFile by searching for some textual value in the FlowFile content (via Regular Expression/regex, or literal value) and replacing the section of the content that matches with some alternate value. It can also be used to append or prepend text to the contents of a FlowFile.

Tags

Change, Modify, Regex, Regular Expression, Replace, Text, Update

Properties

In the list below required Properties are shown with an asterisk (*). Other properties are considered optional. The table also indicates any default values, and whether a property supports the NiFi Expression Language.

Display Name	API Name	Default Value	Allowable Values	Description
Replacement Strategy *	Replacement Strategy	Regex Replace	Prepend Append Surround Regex Replace Literal Replace Always Replace Substitute Variables	The strategy for how and what to replace within the FlowFile's text content.
Search Value *	Regular Expression	(?s)(^.*$)		The Search Value to search for in the FlowFile content. Only used for 'Literal Replace' and 'Regex Replace' matching strategies Supports Expression Language, using FlowFile attributes and Environment variables. This property is only considered if: the property Replacement Strategy has a value of Regex Replace or Literal Replace
Replacement Value *	Replacement Value	$1		The value to insert using the 'Replacement Strategy'. Using "Regex Replace" back-references to Regular Expression capturing groups are supported, but back-references that reference capturing groups that do not exist in the regular expression will be treated as literal value. Back References may also be referenced using the Expression Language, as '$1', '$2', etc. The single-tick marks MUST be included, as these variables are not "Standard" attribute names (attribute names must be quoted unless they contain only numbers, letters, and _). Supports Expression Language, using FlowFile attributes and Environment variables. This property is only considered if: the property Replacement Strategy has a value of Prepend or Regex Replace or Always Replace or Append or Literal Replace
Text to Prepend *	Text to Prepend			The text to prepend to the start of the FlowFile, or each line, depending on the configured value of the Evaluation Mode property Supports Expression Language, using FlowFile attributes and Environment variables. This property is only considered if: the property Replacement Strategy has a value of Surround
Text to Append *	Text to Append			The text to append to the end of the FlowFile, or each line, depending on the configured value of the Evaluation Mode property Supports Expression Language, using FlowFile attributes and Environment variables. This property is only considered if: the property Replacement Strategy has a value of Surround
Character Set *	Character Set	UTF-8		The Character Set in which the file is encoded
Maximum Buffer Size *	Maximum Buffer Size	1 MB		Specifies the maximum amount of data to buffer (per file or per line, depending on the Evaluation Mode) in order to apply the replacement. If 'Entire Text' (in Evaluation Mode) is selected and the FlowFile is larger than this value, the FlowFile will be routed to 'failure'. In 'Line-by-Line' Mode, if a single line is larger than this value, the FlowFile will be routed to 'failure'. A default value of 1 MB is provided, primarily for 'Entire Text' mode. In 'Line-by-Line' Mode, a value such as 8 KB or 16 KB is suggested. This value is ignored if the <Replacement Strategy> property is set to one of: Append, Prepend, Always Replace
Evaluation Mode *	Evaluation Mode	Line-by-Line	Line-by-Line Entire text	Run the 'Replacement Strategy' against each line separately (Line-by-Line) or buffer the entire file into memory (Entire Text) and run against that.
Line-by-Line Evaluation Mode	Line-by-Line Evaluation Mode	All	All First-Line Last-Line Except-First-Line Except-Last-Line	Run the 'Replacement Strategy' against each line separately (Line-by-Line) for all lines in the FlowFile, First Line (Header) alone, Last Line (Footer) alone, Except the First Line (Header) or Except the Last Line (Footer).

Dynamic Properties

This component does not support dynamic properties.

Relationships

Name	Description
failure	FlowFiles that could not be updated are routed to this relationship
success	FlowFiles that have been successfully processed are routed to this relationship. This includes both FlowFiles that had text replaced and those that did not.

Reads Attributes

This processor does not read attributes.

Writes Attributes

This processor does not write attributes.

State Management

This component does not store state.

Restricted

This component is not restricted.

Input Requirement

This component requires an incoming relationship.

Example Use Cases

Use Case 1

Append text to the end of every line in a FlowFile

Configuration

"Evaluation Mode" = "Line-by-Line"
"Replacement Strategy" = "Append"

"Replacement Value" is set to whatever text should be appended to the line.
For example, to insert the text \<fin> at the end of every line, we would set "Replacement Value" to \<fin>.
We can also use Expression Language. So to insert the filename at the end of every line, we set "Replacement Value" to ${filename}

Use Case 2

Prepend text to the beginning of every line in a FlowFile

Configuration

"Evaluation Mode" = "Line-by-Line"
"Replacement Strategy" = "Prepend"

"Replacement Value" is set to whatever text should be prepended to the line.
For example, to insert the text \<start> at the beginning of every line, we would set "Replacement Value" to \<start>.
We can also use Expression Language. So to insert the filename at the beginning of every line, we set "Replacement Value" to ${filename}

Use Case 3

Replace every occurrence of a literal string in the FlowFile with a different value

Configuration

"Evaluation Mode" = "Line-by-Line"
"Replacement Strategy" = "Literal Replace"
"Search Value" is set to whatever text is in the FlowFile that needs to be replaced.
"Replacement Value" is set to the text that should replace the current text.

For example, to replace the word "spider" with "arachnid" we set "Search Value" to spider and set "Replacement Value" to arachnid.

Use Case 4

Transform every occurrence of a literal string in a FlowFile

Configuration

"Evaluation Mode" = "Line-by-Line"
"Replacement Strategy" = "Regex Replace"
"Search Value" is set to a regular expression that matches the text that should be transformed in a capturing group.
"Replacement Value" is set to a NiFi Expression Language expression that references $1 (in quotes to escape the reference name).

For example, if we wanted to lowercase any occurrence of WOLF, TIGER, or LION, we would use a "Search Value" of (WOLF|TIGER|LION) and a "Replacement Value" of ${'$1':toLower()}.
If we want to replace any identifier with a hash of that identifier, we might use a "Search Value" of identifier: (.*) and a "Replacement Value" of identifier: $\{'$1':hash('sha256')}

Use Case 5

Completely replace the contents of a FlowFile to a specific text

Configuration

"Evaluation Mode" = "Entire text"
"Replacement Strategy" = "Always Replace"

"Replacement Value" is set to the new text that should be written to the FlowFile. This text might include NiFi Expression Language to reference one or more attributes.

System Resource Considerations

Scope	Description
MEMORY	An instance of this component can cause high usage of this system resource. Multiple instances or high concurrency settings may result a degradation of performance.

See Also