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Posted to users@nifi.apache.org by "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com> on 2016/03/21 18:34:06 UTC
Help on creating that flow that requires processing attributes in a
flow content but need to preserve the original flow content
What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
Re: Help on creating that flow that requires processing attributes
in a flow content but need to preserve the original flow content
Posted by "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com>.
I’ve entered a Jira issue, NIFI-1660, to enhance the expression language to be able to evaluate a Json path. I plan on submitting a pull request on it in the next week or so.
On 3/22/16, 2:53 AM, "Conrad Crampton" <co...@SecData.com> wrote:
>My 2p.
>If the kaka.key value (very simple json), you could use UpdateAttribute and use some expression language - specifically the string manipulation functions to extract the part you want.
>I like the power or ExecuteProcessor by the way.
>
>And I agree, this community is phenomenally responsive and helpful.
>
>Regards
>Conrad
>
>
>
>
>On 21/03/2016, 18:38, "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com> wrote:
>
>>Thanks everyone. While I’m naturally disappointed that this doesn’t exist, I am hyper charged about the responsiveness and enthusiasm of the NiFi community!
>>
>>From: Matt Burgess <ma...@gmail.com>>
>>Reply-To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
>>Date: Monday, March 21, 2016 at 1:58 PM
>>To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
>>Subject: Re: Help on creating that flow that requires processing attributes in a flow content but need to preserve the original flow content
>>
>>One way (in NiFi 0.5.0+) is to use the ExecuteScript processor, which gives you full control over the session and flowfile(s). For example if you had JSON in your "kafka.key" attribute such as "{"data": {"myKey": "myValue"}}" , you could use the following Groovy script to parse out the value of the 'data.myKey' field:
>>
>>def flowfile = session.get()
>>if(!flowfile) return
>>def json = new groovy.json.JsonSlurper().parseText(flowfile.getAttribute('kafka.key'))
>>flowfile = session.putAttribute(flowfile, 'myKey', json.data.myKey)
>>session.transfer(flowfile, REL_SUCCESS)
>>
>>
>>I put an example of this up as a Gist (https://gist.github.com/mattyb149/478864017ec70d76f74f)
>>
>>A possible improvement could be to add a "jsonPath" function to Expression Language, which could take any value (including an attribute) along with a JSONPath expression to evaluate against it...
>>
>>Regards,
>>Matt
>>
>>On Mon, Mar 21, 2016 at 1:48 PM, McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote) <ch...@hpe.com>> wrote:
>>Joe,
>>
>>Thanks for the reply. I think I was not clear.
>>
>>The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I need to be able to evaluate without modifying the original FlowFile content (which was read from the Kafka topic). What I can’t figure out is how to squirrel away the flowfile content so that I can write the value of the kafka.key attribute to the FlowFile content, so that I can process it with EvaluateJsonPath, and then read content I squirreled away back into the FlowFile content. I considered using the the DistributedMapCache, but there would be no guarantee what I added to the cache would still be there when I needed it back.
>>
>>
>>
>>
>>On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com>> wrote:
>>
>>>Chris,
>>>
>>>Sounds like you have the right flow in mind already. EvaluateJSONPath
>>>does not write content. It merely evaluates the given jsonpath
>>>expression against the content of the flowfile and if appropriate
>>>creates a flowfile attribute of what it finds.
>>>
>>>For example if you have JSON from Twitter you can use EvaluateJsonPath
>>>and add a property with a name
>>>'twitter.user' and a value of '$.user.name<http://user.name>'
>>>
>>>Once you run the tweets through each flow file will have an attribute
>>>called 'twitter.user' with the name found in the message. No
>>>manipulation of content at all. Just promotes things it finds to flow
>>>file attributes.
>>>
>>>Thanks
>>>Joe
>>>
>>>On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
>>>STaTS/StorefrontRemote) <ch...@hpe.com>> wrote:
>>>> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
>>
>>
>>
>> ***This email originated outside SecureData***
>>
>>Click https://www.mailcontrol.com/sr/MZbqvYs5QwJvpeaetUwhCQ== to report this email as spam.
>
>
>SecureData, combating cyber threats
>______________________________________________________________________
>The information contained in this message or any of its attachments may be privileged and confidential and intended for the exclusive use of the intended recipient. If you are not the intended recipient any disclosure, reproduction, distribution or other dissemination or use of this communications is strictly prohibited. The views expressed in this email are those of the individual and not necessarily of SecureData Europe Ltd. Any prices quoted are only valid if followed up by a formal written quote.
>
>SecureData Europe Limited. Registered in England & Wales 04365896. Registered Address: SecureData House, Hermitage Court, Hermitage Lane, Maidstone, Kent, ME16 9NT
Re: Help on creating that flow that requires processing attributes in
a flow content but need to preserve the original flow content
Posted by Conrad Crampton <co...@SecData.com>.
My 2p.
If the kaka.key value (very simple json), you could use UpdateAttribute and use some expression language - specifically the string manipulation functions to extract the part you want.
I like the power or ExecuteProcessor by the way.
And I agree, this community is phenomenally responsive and helpful.
Regards
Conrad
On 21/03/2016, 18:38, "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com> wrote:
>Thanks everyone. While I’m naturally disappointed that this doesn’t exist, I am hyper charged about the responsiveness and enthusiasm of the NiFi community!
>
>From: Matt Burgess <ma...@gmail.com>>
>Reply-To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
>Date: Monday, March 21, 2016 at 1:58 PM
>To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
>Subject: Re: Help on creating that flow that requires processing attributes in a flow content but need to preserve the original flow content
>
>One way (in NiFi 0.5.0+) is to use the ExecuteScript processor, which gives you full control over the session and flowfile(s). For example if you had JSON in your "kafka.key" attribute such as "{"data": {"myKey": "myValue"}}" , you could use the following Groovy script to parse out the value of the 'data.myKey' field:
>
>def flowfile = session.get()
>if(!flowfile) return
>def json = new groovy.json.JsonSlurper().parseText(flowfile.getAttribute('kafka.key'))
>flowfile = session.putAttribute(flowfile, 'myKey', json.data.myKey)
>session.transfer(flowfile, REL_SUCCESS)
>
>
>I put an example of this up as a Gist (https://gist.github.com/mattyb149/478864017ec70d76f74f)
>
>A possible improvement could be to add a "jsonPath" function to Expression Language, which could take any value (including an attribute) along with a JSONPath expression to evaluate against it...
>
>Regards,
>Matt
>
>On Mon, Mar 21, 2016 at 1:48 PM, McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote) <ch...@hpe.com>> wrote:
>Joe,
>
>Thanks for the reply. I think I was not clear.
>
>The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I need to be able to evaluate without modifying the original FlowFile content (which was read from the Kafka topic). What I can’t figure out is how to squirrel away the flowfile content so that I can write the value of the kafka.key attribute to the FlowFile content, so that I can process it with EvaluateJsonPath, and then read content I squirreled away back into the FlowFile content. I considered using the the DistributedMapCache, but there would be no guarantee what I added to the cache would still be there when I needed it back.
>
>
>
>
>On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com>> wrote:
>
>>Chris,
>>
>>Sounds like you have the right flow in mind already. EvaluateJSONPath
>>does not write content. It merely evaluates the given jsonpath
>>expression against the content of the flowfile and if appropriate
>>creates a flowfile attribute of what it finds.
>>
>>For example if you have JSON from Twitter you can use EvaluateJsonPath
>>and add a property with a name
>>'twitter.user' and a value of '$.user.name<http://user.name>'
>>
>>Once you run the tweets through each flow file will have an attribute
>>called 'twitter.user' with the name found in the message. No
>>manipulation of content at all. Just promotes things it finds to flow
>>file attributes.
>>
>>Thanks
>>Joe
>>
>>On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
>>STaTS/StorefrontRemote) <ch...@hpe.com>> wrote:
>>> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
>
>
>
> ***This email originated outside SecureData***
>
>Click https://www.mailcontrol.com/sr/MZbqvYs5QwJvpeaetUwhCQ== to report this email as spam.
SecureData, combating cyber threats
______________________________________________________________________
The information contained in this message or any of its attachments may be privileged and confidential and intended for the exclusive use of the intended recipient. If you are not the intended recipient any disclosure, reproduction, distribution or other dissemination or use of this communications is strictly prohibited. The views expressed in this email are those of the individual and not necessarily of SecureData Europe Ltd. Any prices quoted are only valid if followed up by a formal written quote.
SecureData Europe Limited. Registered in England & Wales 04365896. Registered Address: SecureData House, Hermitage Court, Hermitage Lane, Maidstone, Kent, ME16 9NT
Re: Help on creating that flow that requires processing attributes
in a flow content but need to preserve the original flow content
Posted by "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com>.
Thanks, Liam. I considered that but some of our files are rather large. It may be a short term solution, though.
From: Lee Laim <le...@gmail.com>>
Reply-To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
Date: Monday, March 21, 2016 at 3:17 PM
To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
Subject: Re: Help on creating that flow that requires processing attributes in a flow content but need to preserve the original flow content
Chris,
Depending on the size* of the flowfile content, a combination of ExtractText and ReplaceText might also work.
This is what I am picturing:
ExtractText the entire contents of the flowfile into a new attribute flowfile.original.
ReplaceText with the ${kafka.key}. This will place the ${kafka.key} into the output stream. Then EvaluateJSONPath with the kafka.key, return 'results'.
ExtractText 'results' into another attribute, and swap the original flowfile contents out of the attributes and back into the output stream.
*Having large flowfiles in the attribute space may not be the most efficient for processing and provenance. You may need to adjust the ExtractText property Max Capture Group Length (default is 1024 )to accommodate this flow.
Thanks,
Lee
On Mon, Mar 21, 2016 at 12:38 PM, McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote) <ch...@hpe.com>> wrote:
Thanks everyone. While I’m naturally disappointed that this doesn’t exist, I am hyper charged about the responsiveness and enthusiasm of the NiFi community!
From: Matt Burgess <ma...@gmail.com>>>
Reply-To: "users@nifi.apache.org<ma...@nifi.apache.org>>" <us...@nifi.apache.org>>>
Date: Monday, March 21, 2016 at 1:58 PM
To: "users@nifi.apache.org<ma...@nifi.apache.org>>" <us...@nifi.apache.org>>>
Subject: Re: Help on creating that flow that requires processing attributes in a flow content but need to preserve the original flow content
One way (in NiFi 0.5.0+) is to use the ExecuteScript processor, which gives you full control over the session and flowfile(s). For example if you had JSON in your "kafka.key" attribute such as "{"data": {"myKey": "myValue"}}" , you could use the following Groovy script to parse out the value of the 'data.myKey' field:
def flowfile = session.get()
if(!flowfile) return
def json = new groovy.json.JsonSlurper().parseText(flowfile.getAttribute('kafka.key'))
flowfile = session.putAttribute(flowfile, 'myKey', json.data.myKey)
session.transfer(flowfile, REL_SUCCESS)
I put an example of this up as a Gist (https://gist.github.com/mattyb149/478864017ec70d76f74f)
A possible improvement could be to add a "jsonPath" function to Expression Language, which could take any value (including an attribute) along with a JSONPath expression to evaluate against it...
Regards,
Matt
On Mon, Mar 21, 2016 at 1:48 PM, McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote) <ch...@hpe.com>>> wrote:
Joe,
Thanks for the reply. I think I was not clear.
The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I need to be able to evaluate without modifying the original FlowFile content (which was read from the Kafka topic). What I can’t figure out is how to squirrel away the flowfile content so that I can write the value of the kafka.key attribute to the FlowFile content, so that I can process it with EvaluateJsonPath, and then read content I squirreled away back into the FlowFile content. I considered using the the DistributedMapCache, but there would be no guarantee what I added to the cache would still be there when I needed it back.
On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com>>> wrote:
>Chris,
>
>Sounds like you have the right flow in mind already. EvaluateJSONPath
>does not write content. It merely evaluates the given jsonpath
>expression against the content of the flowfile and if appropriate
>creates a flowfile attribute of what it finds.
>
>For example if you have JSON from Twitter you can use EvaluateJsonPath
>and add a property with a name
>'twitter.user' and a value of '$.user.name<http://user.name><http://user.name>'
>
>Once you run the tweets through each flow file will have an attribute
>called 'twitter.user' with the name found in the message. No
>manipulation of content at all. Just promotes things it finds to flow
>file attributes.
>
>Thanks
>Joe
>
>On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
>STaTS/StorefrontRemote) <ch...@hpe.com>>> wrote:
>> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
Re: Help on creating that flow that requires processing attributes in
a flow content but need to preserve the original flow content
Posted by Lee Laim <le...@gmail.com>.
Chris,
Depending on the size* of the flowfile content, a combination of
ExtractText and ReplaceText might also work.
This is what I am picturing:
ExtractText the entire contents of the flowfile into a new attribute
flowfile.original.
ReplaceText with the ${kafka.key}. This will place the ${kafka.key} into
the output stream. Then EvaluateJSONPath with the kafka.key, return
'results'.
ExtractText 'results' into another attribute, and swap the original
flowfile contents out of the attributes and back into the output stream.
*Having large flowfiles in the attribute space may not be the most
efficient for processing and provenance. You may need to adjust the
ExtractText property Max Capture Group Length (default is 1024 )to
accommodate this flow.
Thanks,
Lee
On Mon, Mar 21, 2016 at 12:38 PM, McDermott, Chris Kevin (MSDU -
STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
> Thanks everyone. While I’m naturally disappointed that this doesn’t
> exist, I am hyper charged about the responsiveness and enthusiasm of the
> NiFi community!
>
> From: Matt Burgess <ma...@gmail.com>>
> Reply-To: "users@nifi.apache.org<ma...@nifi.apache.org>" <
> users@nifi.apache.org<ma...@nifi.apache.org>>
> Date: Monday, March 21, 2016 at 1:58 PM
> To: "users@nifi.apache.org<ma...@nifi.apache.org>" <
> users@nifi.apache.org<ma...@nifi.apache.org>>
> Subject: Re: Help on creating that flow that requires processing
> attributes in a flow content but need to preserve the original flow content
>
> One way (in NiFi 0.5.0+) is to use the ExecuteScript processor, which
> gives you full control over the session and flowfile(s). For example if
> you had JSON in your "kafka.key" attribute such as "{"data": {"myKey":
> "myValue"}}" , you could use the following Groovy script to parse out the
> value of the 'data.myKey' field:
>
> def flowfile = session.get()
> if(!flowfile) return
> def json = new
> groovy.json.JsonSlurper().parseText(flowfile.getAttribute('kafka.key'))
> flowfile = session.putAttribute(flowfile, 'myKey', json.data.myKey)
> session.transfer(flowfile, REL_SUCCESS)
>
>
> I put an example of this up as a Gist (
> https://gist.github.com/mattyb149/478864017ec70d76f74f)
>
> A possible improvement could be to add a "jsonPath" function to Expression
> Language, which could take any value (including an attribute) along with a
> JSONPath expression to evaluate against it...
>
> Regards,
> Matt
>
> On Mon, Mar 21, 2016 at 1:48 PM, McDermott, Chris Kevin (MSDU -
> STaTS/StorefrontRemote) <chris.mcdermott@hpe.com<mailto:
> chris.mcdermott@hpe.com>> wrote:
> Joe,
>
> Thanks for the reply. I think I was not clear.
>
> The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I
> need to be able to evaluate without modifying the original FlowFile content
> (which was read from the Kafka topic). What I can’t figure out is how to
> squirrel away the flowfile content so that I can write the value of the
> kafka.key attribute to the FlowFile content, so that I can process it with
> EvaluateJsonPath, and then read content I squirreled away back into the
> FlowFile content. I considered using the the DistributedMapCache, but there
> would be no guarantee what I added to the cache would still be there when I
> needed it back.
>
>
>
>
> On 3/21/16, 1:37 PM, "Joe Witt" <joe.witt@gmail.com<mailto:
> joe.witt@gmail.com>> wrote:
>
> >Chris,
> >
> >Sounds like you have the right flow in mind already. EvaluateJSONPath
> >does not write content. It merely evaluates the given jsonpath
> >expression against the content of the flowfile and if appropriate
> >creates a flowfile attribute of what it finds.
> >
> >For example if you have JSON from Twitter you can use EvaluateJsonPath
> >and add a property with a name
> >'twitter.user' and a value of '$.user.name<http://user.name>'
> >
> >Once you run the tweets through each flow file will have an attribute
> >called 'twitter.user' with the name found in the message. No
> >manipulation of content at all. Just promotes things it finds to flow
> >file attributes.
> >
> >Thanks
> >Joe
> >
> >On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
> >STaTS/StorefrontRemote) <chris.mcdermott@hpe.com<mailto:
> chris.mcdermott@hpe.com>> wrote:
> >> What I need to do is read a file from Kafka. The Kafka key contains a
> JSON string which I need to turn in FlowFile attributes while preserving
> the original FlowFile content. Obviously I can use EvaluteJsonPath but
> that necessitates replacing the FlowFile content with the kaka.key
> attribute, thus loosing the original FlowFile content. I feel like I’m
> missing something fundamental.
>
>
Re: Help on creating that flow that requires processing attributes
in a flow content but need to preserve the original flow content
Posted by "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com>.
Thanks everyone. While I’m naturally disappointed that this doesn’t exist, I am hyper charged about the responsiveness and enthusiasm of the NiFi community!
From: Matt Burgess <ma...@gmail.com>>
Reply-To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
Date: Monday, March 21, 2016 at 1:58 PM
To: "users@nifi.apache.org<ma...@nifi.apache.org>" <us...@nifi.apache.org>>
Subject: Re: Help on creating that flow that requires processing attributes in a flow content but need to preserve the original flow content
One way (in NiFi 0.5.0+) is to use the ExecuteScript processor, which gives you full control over the session and flowfile(s). For example if you had JSON in your "kafka.key" attribute such as "{"data": {"myKey": "myValue"}}" , you could use the following Groovy script to parse out the value of the 'data.myKey' field:
def flowfile = session.get()
if(!flowfile) return
def json = new groovy.json.JsonSlurper().parseText(flowfile.getAttribute('kafka.key'))
flowfile = session.putAttribute(flowfile, 'myKey', json.data.myKey)
session.transfer(flowfile, REL_SUCCESS)
I put an example of this up as a Gist (https://gist.github.com/mattyb149/478864017ec70d76f74f)
A possible improvement could be to add a "jsonPath" function to Expression Language, which could take any value (including an attribute) along with a JSONPath expression to evaluate against it...
Regards,
Matt
On Mon, Mar 21, 2016 at 1:48 PM, McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote) <ch...@hpe.com>> wrote:
Joe,
Thanks for the reply. I think I was not clear.
The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I need to be able to evaluate without modifying the original FlowFile content (which was read from the Kafka topic). What I can’t figure out is how to squirrel away the flowfile content so that I can write the value of the kafka.key attribute to the FlowFile content, so that I can process it with EvaluateJsonPath, and then read content I squirreled away back into the FlowFile content. I considered using the the DistributedMapCache, but there would be no guarantee what I added to the cache would still be there when I needed it back.
On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com>> wrote:
>Chris,
>
>Sounds like you have the right flow in mind already. EvaluateJSONPath
>does not write content. It merely evaluates the given jsonpath
>expression against the content of the flowfile and if appropriate
>creates a flowfile attribute of what it finds.
>
>For example if you have JSON from Twitter you can use EvaluateJsonPath
>and add a property with a name
>'twitter.user' and a value of '$.user.name<http://user.name>'
>
>Once you run the tweets through each flow file will have an attribute
>called 'twitter.user' with the name found in the message. No
>manipulation of content at all. Just promotes things it finds to flow
>file attributes.
>
>Thanks
>Joe
>
>On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
>STaTS/StorefrontRemote) <ch...@hpe.com>> wrote:
>> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
Re: Help on creating that flow that requires processing attributes in
a flow content but need to preserve the original flow content
Posted by Matt Burgess <ma...@gmail.com>.
One way (in NiFi 0.5.0+) is to use the ExecuteScript processor, which gives
you full control over the session and flowfile(s). For example if you had
JSON in your "kafka.key" attribute such as "{"data": {"myKey": "myValue"}}"
, you could use the following Groovy script to parse out the value of the
'data.myKey' field:
def flowfile = session.get()
if(!flowfile) return
def json = new
groovy.json.JsonSlurper().parseText(flowfile.getAttribute('kafka.key'))
flowfile = session.putAttribute(flowfile, 'myKey', json.data.myKey)
session.transfer(flowfile, REL_SUCCESS)
I put an example of this up as a Gist (
https://gist.github.com/mattyb149/478864017ec70d76f74f)
A possible improvement could be to add a "jsonPath" function to Expression
Language, which could take any value (including an attribute) along with a
JSONPath expression to evaluate against it...
Regards,
Matt
On Mon, Mar 21, 2016 at 1:48 PM, McDermott, Chris Kevin (MSDU -
STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
> Joe,
>
> Thanks for the reply. I think I was not clear.
>
> The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I
> need to be able to evaluate without modifying the original FlowFile content
> (which was read from the Kafka topic). What I can’t figure out is how to
> squirrel away the flowfile content so that I can write the value of the
> kafka.key attribute to the FlowFile content, so that I can process it with
> EvaluateJsonPath, and then read content I squirreled away back into the
> FlowFile content. I considered using the the DistributedMapCache, but there
> would be no guarantee what I added to the cache would still be there when I
> needed it back.
>
>
>
>
> On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com> wrote:
>
> >Chris,
> >
> >Sounds like you have the right flow in mind already. EvaluateJSONPath
> >does not write content. It merely evaluates the given jsonpath
> >expression against the content of the flowfile and if appropriate
> >creates a flowfile attribute of what it finds.
> >
> >For example if you have JSON from Twitter you can use EvaluateJsonPath
> >and add a property with a name
> >'twitter.user' and a value of '$.user.name'
> >
> >Once you run the tweets through each flow file will have an attribute
> >called 'twitter.user' with the name found in the message. No
> >manipulation of content at all. Just promotes things it finds to flow
> >file attributes.
> >
> >Thanks
> >Joe
> >
> >On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
> >STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
> >> What I need to do is read a file from Kafka. The Kafka key contains a
> JSON string which I need to turn in FlowFile attributes while preserving
> the original FlowFile content. Obviously I can use EvaluteJsonPath but
> that necessitates replacing the FlowFile content with the kaka.key
> attribute, thus loosing the original FlowFile content. I feel like I’m
> missing something fundamental.
>
Re: Help on creating that flow that requires processing attributes in
a flow content but need to preserve the original flow content
Posted by Joe Witt <jo...@gmail.com>.
Chris - also you were clear. I was just too quick to reply and didn't
read carefully.
On Mon, Mar 21, 2016 at 1:53 PM, Mark Payne <ma...@hotmail.com> wrote:
> Chris,
>
> Unfortunately, at this time, the EvaluateJsonPath requires that the JSON to evaluate be the content of the FlowFIle.
> There already does exist a ticket [1] that would allow you to specify an attribute to use as the JSON instead of
> requiring that it be the content only. Unfortunately, this has not yet been implemented.
>
> Thanks
> -Mark
>
> [1] https://issues.apache.org/jira/browse/NIFI-1567
>
>
>> On Mar 21, 2016, at 1:48 PM, McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
>>
>> Joe,
>>
>> Thanks for the reply. I think I was not clear.
>>
>> The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I need to be able to evaluate without modifying the original FlowFile content (which was read from the Kafka topic). What I can’t figure out is how to squirrel away the flowfile content so that I can write the value of the kafka.key attribute to the FlowFile content, so that I can process it with EvaluateJsonPath, and then read content I squirreled away back into the FlowFile content. I considered using the the DistributedMapCache, but there would be no guarantee what I added to the cache would still be there when I needed it back.
>>
>>
>>
>>
>> On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com> wrote:
>>
>>> Chris,
>>>
>>> Sounds like you have the right flow in mind already. EvaluateJSONPath
>>> does not write content. It merely evaluates the given jsonpath
>>> expression against the content of the flowfile and if appropriate
>>> creates a flowfile attribute of what it finds.
>>>
>>> For example if you have JSON from Twitter you can use EvaluateJsonPath
>>> and add a property with a name
>>> 'twitter.user' and a value of '$.user.name'
>>>
>>> Once you run the tweets through each flow file will have an attribute
>>> called 'twitter.user' with the name found in the message. No
>>> manipulation of content at all. Just promotes things it finds to flow
>>> file attributes.
>>>
>>> Thanks
>>> Joe
>>>
>>> On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
>>> STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
>>>> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
>
Re: Help on creating that flow that requires processing attributes in a flow content but need to preserve the original flow content
Posted by Mark Payne <ma...@hotmail.com>.
Chris,
Unfortunately, at this time, the EvaluateJsonPath requires that the JSON to evaluate be the content of the FlowFIle.
There already does exist a ticket [1] that would allow you to specify an attribute to use as the JSON instead of
requiring that it be the content only. Unfortunately, this has not yet been implemented.
Thanks
-Mark
[1] https://issues.apache.org/jira/browse/NIFI-1567
> On Mar 21, 2016, at 1:48 PM, McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
>
> Joe,
>
> Thanks for the reply. I think I was not clear.
>
> The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I need to be able to evaluate without modifying the original FlowFile content (which was read from the Kafka topic). What I can’t figure out is how to squirrel away the flowfile content so that I can write the value of the kafka.key attribute to the FlowFile content, so that I can process it with EvaluateJsonPath, and then read content I squirreled away back into the FlowFile content. I considered using the the DistributedMapCache, but there would be no guarantee what I added to the cache would still be there when I needed it back.
>
>
>
>
> On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com> wrote:
>
>> Chris,
>>
>> Sounds like you have the right flow in mind already. EvaluateJSONPath
>> does not write content. It merely evaluates the given jsonpath
>> expression against the content of the flowfile and if appropriate
>> creates a flowfile attribute of what it finds.
>>
>> For example if you have JSON from Twitter you can use EvaluateJsonPath
>> and add a property with a name
>> 'twitter.user' and a value of '$.user.name'
>>
>> Once you run the tweets through each flow file will have an attribute
>> called 'twitter.user' with the name found in the message. No
>> manipulation of content at all. Just promotes things it finds to flow
>> file attributes.
>>
>> Thanks
>> Joe
>>
>> On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
>> STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
>>> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
Re: Help on creating that flow that requires processing attributes
in a flow content but need to preserve the original flow content
Posted by "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com>.
Joe,
Thanks for the reply. I think I was not clear.
The JSON I need to evaluate is in a FlowFile attribute (kafka.key) which I need to be able to evaluate without modifying the original FlowFile content (which was read from the Kafka topic). What I can’t figure out is how to squirrel away the flowfile content so that I can write the value of the kafka.key attribute to the FlowFile content, so that I can process it with EvaluateJsonPath, and then read content I squirreled away back into the FlowFile content. I considered using the the DistributedMapCache, but there would be no guarantee what I added to the cache would still be there when I needed it back.
On 3/21/16, 1:37 PM, "Joe Witt" <jo...@gmail.com> wrote:
>Chris,
>
>Sounds like you have the right flow in mind already. EvaluateJSONPath
>does not write content. It merely evaluates the given jsonpath
>expression against the content of the flowfile and if appropriate
>creates a flowfile attribute of what it finds.
>
>For example if you have JSON from Twitter you can use EvaluateJsonPath
>and add a property with a name
>'twitter.user' and a value of '$.user.name'
>
>Once you run the tweets through each flow file will have an attribute
>called 'twitter.user' with the name found in the message. No
>manipulation of content at all. Just promotes things it finds to flow
>file attributes.
>
>Thanks
>Joe
>
>On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
>STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
>> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
Re: Help on creating that flow that requires processing attributes in
a flow content but need to preserve the original flow content
Posted by Joe Witt <jo...@gmail.com>.
Chris,
Sounds like you have the right flow in mind already. EvaluateJSONPath
does not write content. It merely evaluates the given jsonpath
expression against the content of the flowfile and if appropriate
creates a flowfile attribute of what it finds.
For example if you have JSON from Twitter you can use EvaluateJsonPath
and add a property with a name
'twitter.user' and a value of '$.user.name'
Once you run the tweets through each flow file will have an attribute
called 'twitter.user' with the name found in the message. No
manipulation of content at all. Just promotes things it finds to flow
file attributes.
Thanks
Joe
On Mon, Mar 21, 2016 at 1:34 PM, McDermott, Chris Kevin (MSDU -
STaTS/StorefrontRemote) <ch...@hpe.com> wrote:
> What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.
Re: Help on creating that flow that requires processing attributes
in a flow content but need to preserve the original flow content
Posted by Joe Percivall <jo...@yahoo.com>.
Hello Chris,
The EvaluateJsonPath processor has the property "Destination" which gives you the option to send it either to the FlowFile content or a FlowFile attribute. Selecting "flowfile-attribute" will place the value in the "kafka.key" attribute of the FlowFile. You can find documentation for EvaluateJsonPath here[1].
[1] https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi.processors.standard.EvaluateJsonPath/index.html
Hope your NiFi use is going well,
Joe
- - - - - -
Joseph Percivall
linkedin.com/in/Percivall
e: joepercivall@yahoo.com
On Monday, March 21, 2016 1:34 PM, "McDermott, Chris Kevin (MSDU - STaTS/StorefrontRemote)" <ch...@hpe.com> wrote:
What I need to do is read a file from Kafka. The Kafka key contains a JSON string which I need to turn in FlowFile attributes while preserving the original FlowFile content. Obviously I can use EvaluteJsonPath but that necessitates replacing the FlowFile content with the kaka.key attribute, thus loosing the original FlowFile content. I feel like I’m missing something fundamental.