Joe, These would be breaking changes and a lot of existing workflows would begin to behave differently. I would suggest making an incremental change here — simply adding replaceFirst as a non-destructive change as a solution for this issue, and opening a new Jira for the changes which break backward compatibility.
I do agree that option 1 is probably the cleaner way forward, and if we introduce new method names, we may be able to use StandardFlowSynchronizer to detect legacy methods from a pre-1.0 flow and update them automatically during flow migration. Andy LoPresto [email protected] [email protected] PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4 BACE 3C6E F65B 2F7D EF69 > On May 25, 2016, at 4:06 PM, Joe Percivall <[email protected]> > wrote: > > Andy, > > Nice write-up and thanks for bringing attention to this. I definitely assumed > for a while that replace vs replaceAll was the number of things replaced. The > underlying problem, I think, is that these EL methods are just wrappers > around the Java String methods and the Java String methods are named in a > confusing manner. > > I am on board with adding a "replaceFirst(regex, replacement)" method. This > adds a bit more functionality and is just exposing another Java String method. > > In addition to that, I would suggest doing something to alleviate the > confusion between "replace" and "replaceAll". In a similar fashion to adding > decimal support, I see two avenues we could take: > > 1. Change the names of the functions to "replaceLiteral" and "replaceRegex" > (or "replaceAllLiteral" and "replaceAllRegex") > 2. Remove one of the methods and add a third field to the remaining method to > indicate whether to replace literally or interpret as a regex > > Both of these would be breaking changes and introduced with 1.0 and I am > leaning towards option 1 with the base name "replace". I believe when the > "replaceFirst" method is added, "replaceLiteral" and "replaceRegex" would be > easy to understand that they replace all occurrences. > > Joe > > - - - - - - > Joseph Percivall > linkedin.com/in/Percivall > e: [email protected] > > > > On Wednesday, May 25, 2016 6:24 PM, Andy LoPresto <[email protected]> > wrote: > > > > Hi all, > > During investigation of an expression language issue posted to the list, I > discovered that replace explicitly delegates to a String#replace invocation > that only accepts literal expressions, not regular expressions, while > replaceAll accepts regular expressions. I thought this was an oversight and > filed NIFI-1919 [1] to document and fix this, by changing the > ReplaceEvaluator [2] to use String#replaceFirst, which accepts regular > expressions. I wrote failing unit tests [3] to capture the fix. After > implementing the change, two existing unit tests [4] broke, which indicated a > regression. At first, I believed these two tests to be incorrect, but further > investigation showed they were merely surprising. > > TestQuery#testQuotingQuotes (below) fails on the second verifyEquals call, > but the test is asserting that replace should replace multiple instances of > the single quote. While this is similar to String#replace, because the > expression language exposes only two methods — replace vs. replaceAll — one > could easily assume the difference between the two was the number of > attempted replacements, rather than the actual difference, which is literal > expression vs. pattern. > > @Test > public void testQuotingQuotes() { > final Map<String, String> attributes = new HashMap<>(); > attributes.put("xx", "say 'hi'"); > > String query = "${xx:replaceAll( \"'.*'\", '\\\"hello\\\"' )}"; > verifyEquals(query, attributes, "say \"hello\""); > > query = "${xx:replace( \"'\", '\"')}"; > verifyEquals(query, attributes, "say \"hi\""); > > query = "${xx:replace( '\\'', '\"')}"; > System.out.println(query); > verifyEquals(query, attributes, "say \"hi\""); > } > TestQuery#testReplaceAllWithOddNumberOfBackslashPairs (below) also fails on > the first verifyEquals call with a PatternSyntaxException. I am investigating > that further. > > @Test > public void testReplaceAllWithOddNumberOfBackslashPairs() { > final Map<String, String> attributes = new HashMap<>(); > attributes.put("filename", "C:\\temp\\.txt"); > > verifyEquals("${filename:replace('\\\\', '/')}", attributes, "C:/temp/.txt"); > verifyEquals("${filename:replaceAll('\\\\\\\\', '/')}", attributes, > "C:/temp/.txt"); > verifyEquals("${filename:replaceAll('\\\\\\.txt$', '')}", attributes, > "C:\\temp"); > } > While I originally had just modified replace, after looking at the EL > documentation [5], replace is explicitly documented to only replace literal > expressions, and does so multiple times, as does Java’s String#replace [6]. I > now propose to add another method replaceFirst, which accepts a pattern and > replaces only the first occurrence. I will update the unit tests to properly > capture this, and will update the documentation to reflect the new method. > > Thoughts from the community? > > [1] https://issues.apache.org/jira/browse/NIFI-1919 > [2] > https://github.com/alopresto/nifi/blob/NIFI-1919/nifi-commons/nifi-expression-language/src/main/java/org/apache/nifi/attribute/expression/language/evaluation/functions/ReplaceEvaluator.java > [3] > https://github.com/alopresto/nifi/blob/NIFI-1919/nifi-commons/nifi-expression-language/src/test/groovy/org/apache/nifi/attribute/expression/language/QueryGroovyTest.groovy > [4] > https://github.com/alopresto/nifi/blob/NIFI-1919/nifi-commons/nifi-expression-language/src/test/java/org/apache/nifi/attribute/expression/language/TestQuery.java > [5] > https://nifi.apache.org/docs/nifi-docs/html/expression-language-guide.html#replace > [6] > https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#replace(java.lang.CharSequence,%20java.lang.CharSequence) > > > > Andy LoPresto > [email protected] > [email protected] > PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4 BACE 3C6E F65B 2F7D EF69
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