replaceFirst (Function)

Finds the first substring of the input string that matches with the given regular expression, and replaces it with the given replacement string.

Syntax

<STRING> str:replaceFirst(<STRING> input.string, <STRING> regex, <STRING> replacement.string)

Query Parameters

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
input.string	The input string that should be replaced.		STRING	No	Yes
regex	The regular expression with which the input string should be matched.		STRING	No	Yes
replacement.string	The string with which the first substring of input string that matches the regular expression should be replaced.		STRING	No	Yes

Example 1

@info(name = 'replaceFirstExample')
SELECT str:replaceFirst('hello gdn A hello', 'gdn(.*)A', 'XXXX') AS replacedFirstString;

The replaceFirstExample demonstrates the use of the str:replaceFirst() function to replace the first occurrence of a specified substring in the input string with a replacement string. In this example, the input string is 'hello gdn A hello', the substring to replace is specified by the regular expression 'gdn(.*)A', and the replacement string is 'XXXX'. The function returns 'hello XXXX hello', which is the input string with the first occurrence of the specified substring replaced by 'XXXX'.

Example 2

CREATE STREAM InputDataStream (eventTime long, inputString string, targetSubstring string, replacement string);
CREATE SINK STREAM OutputStream (eventTime long, replacedFirstString string);

@info(name = 'replaceFirstStreamWorker')
INSERT INTO OutputStream
SELECT eventTime, str:replaceFirst(inputString, targetSubstring, replacement) AS replacedFirstString
FROM InputDataStream;

The replaceFirstStreamWorker processes events from the InputDataStream and uses the str:replaceFirst() function to replace the first occurrence of the targetSubstring attribute in the inputString attribute with the provided replacement attribute. The query outputs the eventTime and the resulting replacedFirstString for each event to the OutputStream.