Paul, I strongly encourage you to consider the Apache Software Foundation's Code of Conduct as you interact with this community [1].
[1] http://www.apache.org/foundation/policies/conduct.html Thanks Joe On Wed, Mar 23, 2016 at 5:58 PM, Paul Nahay <pna...@sprynet.com> wrote: > Wow. Thanks. > > > > This seems unnecessarily complicated using the “Advanced” feature, given it’s > a standard boolean evaluation I’m trying to do. But I’m glad to hear there’s > some way to do it. > > > > You know, assuming NiFi is written in Java (which I presume it is, if the > custom processors are as well), when the day comes where you realize your > Expression Language is simply too limited and quirky for anyone to stand any > longer (that day is HERE for me, now!), I would humbly suggest you guys make > use of Java 8 Nashorn. Then you could allow NiFi developers to embed > arbitrary JavaScript in your little window, rather than your crazy, > exists-no-where-else-on-earth E.L. > > > > Then one could simply create expressions representing “a and b are not empty > or c is not empty” without the complexity of the E.L. itself, or forcing one > to use the Advanced dialog, but using JavaScript, which is almost the world’s > 2nd most used programming language at this point. > > > > Paul > > > > From: Matthew Clarke [mailto:matt.clarke....@gmail.com] > Sent: Wednesday, March 23, 2016 12:26 PM > To: Paul Nahay > Cc: dev@nifi.apache.org > Subject: Re: notEmpty > > > > Paul, > > The expression you have above ( > ${allAttributes('x','y'):isEmpty():not():or(${z:isEmpty():not()})} ) will > not logically result in the same outcome as ( > ${allAttributes('x','y','z'):isEmpty():not()} ). I understand you > realize this, but I just want to clarify it for the rest of the community > reading this thread. > > Assuming x and/or y are empty and z is not empty, your expression will result > in a true. Your understanding of how this would be parsed is correct. > > assume x is blank, y = 1, and z = 2. so the expression would evaluate to > (attribute x is not empty (false) or attribute z is not empty (true) ) and > (attribute y is not empty (true) or attribute z is not empty (true)) which > breaks down further to (false or true = true) and (true or true = true) which > finally results in (true and true = true). So as you can see as long as z > is not empty, your expression will resolve to true. > > So you are correct that z would get evaluated for every attribute declared > in the allAttributes() function. > > > To avoid evaluating z multiple times in this particular use case, you > would want to make use of the "Advanced" capability of the updateAttribute > processor. When you open the configuration window for the UpdateAttribute > processor, you will notice an "Advanced" button in the lower right corner. > This well open the advanced configuration UI for the UpdateAttribute. Here > you can essentially build if/then logic. In your case you would add two new > "rules" and set the "FlowFile policy" to "use original" > > rule 1 would check to see if z is not empty. The condition must evaluate to > "true" before the associated actions are applied. The action could set a new > attribute with a value of true > rule 2 would check to see if AllAttributes(x,y,a,b,c,etc) are not empty. if > evaluated to true, the action would set the "same" attribute used in rule 1 > to true. > > So essentially you are saying if this or if this set this. If both rules > resolve to true and policy is set to use original, the last rule evaluated to > true will set the attribute. > > The else part of the if/then/else logic here is achieved outside of the > "Advanced" UI. There you could declare the "same" attribute again but set it > to a value of false. > > The way this works.... If an attribute is declared both inside and outside > the "Advanced" UI, the value set outside the "advanced" UI will only be > applied to the FlowFile if it was not set by one of the rules. > > This process would result in evaluating z only once for each FlowFile. > > > > You can then use this newly created attribute later in your dataflow for > additional logic checks, routing, etc... > > More information on the updateAttribute "Advanced" UI can be found here: > https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi.processors.attributes.UpdateAttribute/additionalDetails.html > > > > Matt > > > > > > On Wed, Mar 23, 2016 at 10:28 AM, Paul Nahay <pna...@sprynet.com> wrote: > > OK, I am still confused about how to implement this boolean expression with > the EL: > > (attributes x and y are both not empty) or (attribute z is not empty) > > If I do this: > > ${allAttributes('x','y'):isEmpty():not():or(${z:isEmpty():not()})} > > from my understanding of your documentation about the allAttributes() > function, then the EL above is doing this (due to ":or()" coming right after > ":not()"): > > (attribute x is not empty or attribute z is not empty) and (attribute y is > not empty or attribute z is not empty) > > I realize logically this ends up being the same thing in the end, however, > the "z is not empty" part gets evaluated TWICE, or as many times as there are > parameters passed to allAttributes() (i.e., if we had instead > "allAttributes('1','2','3','4','5'), then testing z for non-emptiness occurs > five times, not once). > > Is there any way to actually express in the NiFi EL my boolean at the top of > my message above? > > > > Paul > > > > > -----Original Message----- > From: Matthew Clarke > Sent: Mar 22, 2016 8:17 PM > To: Paul Nahay > Subject: Re: notEmpty > > Paul, > > While i do agree that the addition of a notEmpty function would be nice, > I was simply offering an alternative solution to your particular problem. > The solution I provided does indeed work. I built a test flow to verify it. > > I created some test files with the following attributes on them: > > Property: Value: > attr1 > > attr2 > > attr3 > > attr4 1 > > attr5 2 > > attr6 3 > > > > Those files were sent to a routeOnAttribute processor where I used that > expression language statement to find route where all attributes were not > empty. > > RouteOnAttribute: > > Property: Value: > AllAttributesNotEmpty > ${allAttributes('attr1','attr2','attr3'):isEmpty():not()} <--- I > changed what attributes to look at in each test. > > > I then varied what attribute I was looking at using the AllAttributes > function. > First I looked at attr1, attr2, and attr3 <--- files routed to > unmatched as expected > Second I looked at attr3, attr4, and attr5 <--- again all files routed > to unmatched since one of the attributes (attr3) was empty > > Third I looked at attr4, attr5, and attr6 <--- All files routed to > the AllAttributesNotEmpty relationship as expected. > > Perhaps I did not follow your use case correctly, but the above is what I > believed you were looking for. > > > > Matt > > > > On Tue, Mar 22, 2016 at 6:39 PM, Paul Nahay <pna...@sprynet.com> wrote: > > Thanks for responding, however... > > > > Your expression below evaluates to true if IT IS NOT THE CASE THAT ALL THREE > ATTRIBUTES ARE EMPTY. > > > > But I need an expression that evalutes to true if IT IS THE CASE THAT ALL > THREE ATTRIBUTES ARE NOT EMPTY. > > > > There are two entirely different things. > > > > Thus, if attr1 is set (thus is “not empty”), but the others are not (thus > they “are empty”), your expression evaluates to true. > > > > But I need to ensure that NONE of the three “are empty”. I want an expression > that in the case given above evaluates to false. > > > > Actually, I know how to make an expression that does what I need, however, it > is more confusing than it needs to be. The simpler expression that one would > desire to write REQUIRES that you offered a “notEmpty” function, thus would > be expressible as: > > > > ${allAttributes('attr1','attr2','attr3'):notEmpty()} > > > > Again, this gives true only if all three attributes are not empty. The > expression you suggest gives true if even only ONE of the attributes is not > empty! > > > > The lack of “notEmpty()” seems a very grave omission on your part. > > > > And, you have no comment about the errors in your documentation for “isEmpty” > and “allAttributes” that I told you? > > > > --Paul Nahay > > > > > > > > From: Matthew Clarke [mailto:matt.clarke....@gmail.com] > Sent: Tuesday, March 22, 2016 11:07 AM > To: dev@nifi.apache.org; Paul Nahay > Subject: Re: notEmpty > > > > Paul, > > You can achieve what you are trying to do by using the not function. > > > > let assume the attributes you want to check to make sure they have a vlaue > set are attr1, attr2, and attr3. > > The expression would be > ${allAttributes('attr1','attr2','attr3'):isEmpty():not()} > > Thanks, > > Matt > > > > On Tue, Mar 22, 2016 at 9:46 AM, Paul Nahay <pna...@sprynet.com> wrote: > > https://nifi.apache.org/docs/nifi-docs/html/expression-language-guide.html#isempty > > Why don't you have function "notEmpty"? This would be useful when combined > with "allAttributes". > > I can't see any way, with your current set of functions, to determine that > all of a set of attributes are not empty, using the "allAttributes" function. > > You have "isNull" and "notNull", why don't you have "notEmpty"? > > Paul Nahay > pna...@sprynet.com > > > > > > > > > > >
