Michael,
Well, sort of...
You could use:
${allDelineatedValues('${fileArray}', ','):count()}
So that will split up the fileArray attribute by commas and then count them.
The only issue is that if you were to have a filename with a comma in it, you'd
get the wrong value. Given that your'e not likely to have a filename with a
comma, you may be all right, but it's not really the "cleanest" solution...
The Expression language does allow you to evaluate JSONPath against an
attribute but JSONPath doesn't allow for the nice functions that you can get in
XPath and similar.
Anyone else have any better ideas?
> On Aug 10, 2016, at 3:32 PM, Michael Xu <[email protected]> wrote:
>
> Hi Mark,
>
> Thanks for your response earlier. While trying to implement what you
> suggested in your email, I came across the issue of updating fragment.count
> on a per-flowfile basis. I have another attribute called fileArray, which is
> a json-compatible array that contains all the files for a particular groupId.
> As an example taken from the Bulletin:
>
> Key: 'fileArray'
> Value: '["file1.txt","file2.txt","file3.txt"]'
>
> Is it possible in UpdateAttribute to use the Expression Language to return
> the length of this array?
>
> Thanks for your help,
> Michael
>
> On Wed, Aug 10, 2016 at 11:00 AM, Mark Payne <[email protected]
> <mailto:[email protected]>> wrote:
> Michael,
>
> In the MergeContent processor, you can set the "Merge Strategy" to
> "Defragment." This will tell Merge Content to
> determine its bin thresholds based on the following FlowFile attributes:
>
> fragment.identifier
> fragment.index
> fragment.count
>
> So you'd need to set those 3 attributes on each of the FlowFiles. Rather than
> using the Correlation Attribute Name,
> you'd set the "fragment.identifier" attribute (you can use UpdateAttribute to
> copy the value from the groupId attribute
> to the 'fragment.identifier' attribute if you need to).
>
> The "fragment.index" attribute tells MergeContent how to order the different
> FlowFiles in the merged bin.
>
> The "fragment.count" attribute tells MergeContent how many FlowFiles go this
> bin.
>
> Does that all make sense?
>
> Thanks
> -Mark
>
>
>> On Aug 10, 2016, at 10:54 AM, Michael Xu <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> I am sending into the MergeContent processor, payloads that each belong in a
>> certain group of files in some data I'm working with. Each payload has an
>> attribute called "groupId" which is an identification number for a
>> particular group of files. This is the attribute I'm using to bin each
>> incoming flowfile, and have set the Correlation Attribute Name to groupId.
>>
>> The problem I'm dealing with right now is that each groupId has a varying
>> number of files associated with it. As such, I'm not sure how in NiFi to
>> detect when the MergeContent processor has received all files for a
>> particular groupId, and once done, release the bin.
>>
>> Any help with this problem is appreciated, thanks!
>
>
