I have two goals here for the information embedded in the array.
The first goal is to be able to do some kind of aggregation on the array.
For example, given {"company":"xyz", "rate":[0.02, 0.03, 0.04]}, if we
could have a Json variable "rate", I would like to have something such as
${rate[*]:count()} that would give me a scalar value of the count. Then I
can assign the value to a property of a processor under Nifi. But,
currently under Nifi, $.rate is not a valid expression. Therefore,
$.rate[*]:count() is not valid either. Nifi flow would give me errors and
failed if I did that.
My second goal is to be able to carry the array forward but turn it into a
scalar structure as a single string such as (0.02, 0.03, 0.04). I have
experimented the setups you suggested. I explicitly configured the
destination as flowfile-content and return type as Json. This time, Nifi
flow did not complain about any error any more but it did not capture
anything either in the end.
I would say my first goal is very important for my project.
Thank you all for your help.
Hong
*Hong Li*
*Centric Consulting*
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On Wed, Apr 6, 2016 at 2:35 PM, Thad Guidry <thadgui...@gmail.com> wrote:
> Does it store as an attribute if you change the return type from
> auto-detect to JSON ?
>
> *Return Type* auto-detect
>
> - auto-detect
> - json
> - scalar
>
> Indicates the desired return type of the JSON Path expressions. Selecting
> 'auto-detect' will set the return type to 'json' for a Destination of
> 'flowfile-content', and 'scalar' for a Destination of 'flowfile-attribute'.
>
> https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi.processors.standard.EvaluateJsonPath/index.html
>
>
> Depending on your use case.... you might want to store those rate values
> as content rather than attributes....but depends on what your trying to
> accomplish. You are not limited to changing your flow with just
> EvaluateionJsonPath... you can probably add an additional processor after
> it to do further filtering or setting of attributes, rather than trying to
> just do it all in one shot with the EvaluateJsonPath processor.
>
> Thad
> +ThadGuidry <https://www.google.com/+ThadGuidry>
>
