while using RouteOnAttribute nifi processor , i have input of json data
[{"dev":"xyz","detail":"abc"}] which i got from convertRecord processor
Routing Strategy :Route to Property name
ifmatch: ${dev:equals( "xyz" )}
I tried ${dev:matches( "xyz")} in both single quotes and double quotes still am not getting flowfile redirecting towards "ifmatch" . its redirecting to unmatched
is there anyway to resolve this i tried many other option
The flowfile content is different from attributes. Content is arbitrary -- could be empty, text, KB of XML, GB of video or binary. Each flowfile also has attributes which are key/value pairs of Strings kept in memory.
If you want to route on this piece of data, you have multiple options:
Use RouteOnText or RouteOnContent to use the actual flowfile content directly.
Extract it to an attribute using EvaluateJsonPath and then route on that attribute.
The Apache NiFi User Guide and In-Depth provide more information around this distinction.
Related
I need some help in UpdateAttribute processor:
I have a CSV file which contains hostnames. I need to separate each hostname in the FlowFile and pass it as a variable to the REST API.
My REST API part is working fine when passing data manually. However, I didn't get how to pass a variable value as hostname in it.
Sharing sample file:
SRHAPP001,SRHWEBAPP002,SRHDB006,SRHUATAPP4,ARHUATDB98
I don't quite understand your goal, but I assume that you try to pass the hostname to your REST API module by using FlowFile variables.
You can achieve this by using the ExtractText-Processor. You simply use RegEx for separating your hostnames from the CSV file.
For more information, see
https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi/nifi-standard-nar/1.12.1/org.apache.nifi.processors.standard.ExtractText/
How can I extract a substring from a flowfile data in Nifi?
If needed, you can split incoming FlowFiles on every hostname by using SplitContent-Processor
NiFi Version 1.8.0
I'm trying to build our my json, and one of my fields needs to be an array. I thought I could simply use the UpdateAttribute Processor to set my attribute to '["arrayItem1", "arrayItem2"]' and then I could used AttributeToJSON to convert the attribute to JSON and it would convert to an array. Unfortunately, it simply turns into a string.
In the simplest way, how can I set an attribute to be an array so my final JSON (when using AttributeToJSON) field has the specific array?
EDIT 1
I will have a few SyslogListeners, I want to set an attribute so I know what data came from where. I want to be able to tag this data, so I though of adding an UpdateAttribute to set my attribute. I would like this to be an array. So the tag for:
SyslogListener1 will be ["tag1", "tag2"]
SyslogListener2 will be ["tag3", "tag4"]
SyslogListener3 will be ["tag1", "tag3"]
I thought of just having my flow look like this: SyslogListener -> UpdateAttribute -> Then all the data is now in the main flow -> AttributeToJSON. However, when I look at my JSON, my field is a string, not an array. How can I make this field to be an array? What I used to do, was use ReplaceText , the only problem with this is I didn't want to create a ReplaceText for ever single instance. Is there a single processor that could handle this?
Does your incoming flow file have any existing content? If not, you can use ReplaceContent to set the content to ["arrayItem1", "arrayItem2"] or whatever you wish the JSON to look like.
If the incoming flow file has existing JSON content, you can add the field explicitly (without attributes) using JoltTransformJSON or UpdateRecord.
Not my ideal solution, but I simply added a ReplaceText for each instance I would need. In my case, it was 7 different tag formations. So my nifi looks a little ugly. I was hoping for a single processor solution where I could tell it my JSON field and make it an array. So my pipeline is:
SyslogListener -> UpdateAttribute (creates our tags attribute with the string tag1, tag2 and the other tag combinations because I have 7 total SyslogListeners with their own UpdateAttribute) -> Data is now in the main pipeline, and some Other processing stuff happens here -> AttributeToJSON (setting our json with some attributes including our tags attribute) -> My 7 ReplaceTexts (which checks to see if our tags field has "tag1, tag2" and then replaces it with ["tag1", "tag2"], I do this for all 7 cases) -> PutElasticSearchHttp
So ingesting rsyslog messages, doing a bit of enriching, making my data into a JSON, then saving it to ES.
If anyone knows a single processor solution to this, so I don't need to have 7 unique ReplaceTexts (and more if I need new tags).
I have JSON objects coming into Nifi via MQTT from two different inputs - for instance, let's say one is from a top sensor, and one is from a bottom sensor. Each of the sensors has its own MQTT topic, so I am using two different ConsumeMQTT Processors to ingest this data into my Nifi Flow.
JSON Object for top sensor is {"Top_Data": "value"}
JSON Object for bottom sensor is {"Bottom_Data": "value"}
I am currently using two separate EvaluateJsonPath Processors to store either the value of Top_Data or Bottom_Data in an attribute called sensorData.
How can I use some kind of if/or statement to only use one processor to EvaluateJsonPath for both of the JSON objects I could get from MQTT? Basically, I want to have an expression that says "If my JSON object has a property called Top_Data, use its value for the attribute sensorData, otherwise, use the value from the property Bottom_Data."
Example of my EvaluateJsonPath Processor
maybe try JSONPath expression
$[Top_Data,Bottom_Data]
in the single EvaluateJSONPathProcessor.
According to https://goessner.net/articles/JsonPath/ there is a possibility to use alternate operator [,]:
[,] Union operator in XPath results in a combination of node sets. JSONPath allows alternate names or array indices as a set.
I have tested the expression using http://jsonpath.com/ and it should work.
Let us know if that helps.
You could try extracting them both using EvaluateJsonPath(property 1: top: $['top'], property 2: bottom: $['bottom']) and of course don't forget to set Destination to flowfile-attribute.
Then, transfer to UpdateAttribute and set property finalData as ${top:isEmpty():ifElse(${bottom}, ${top})}.
If EvaluateJsonPath won't find a full element, then it will set it as empty string, so all you need to do is check if either of them is empty and if it is, set the final data as the other one.
I need to perform an HTTP Post from NiFi, but I don't want/need the request to carry all of the FlowFile's content.
Is there some way to pass attributes of a FlowFile but not the full content?
If the request body of your Http Post is JSON, you can use the AttributesToJSON Processor which allows you to pick which attributes you want to include in the resulting JSON. You can then configure the processor so the resulting JSON overwrites the existing flowfile content.
Keep in mind that the resulting JSON will be flat so you may need to transform it to the expected format. For that, you can use the JoltTransformJSON Processor.
Below is an example of what your dataflow might look like. I hope this helps!
New to NiFi!
I've split a flowfile into a single line of text using splitJSON processor.
The NiFi flowfile contents are as follows:
abcdefg
I'd like to be able to take the text in the flowfile and either add it to a url to make a subsequent call using InvokeHTTP or add the contents of the flowfile as an attribute so I can make the subsequent call using InvokeHTTP like so
http://localhost/${my.newly.added.attribute}
How do i do this?
Any help would be appreciated!
Thanks in advance!
ExtractText will allow you to find sections of content and place in an attribute on the FlowFile. For your example, you could capture the entirety of the content and assign to an attribute my.newly.added.attribute. InvokeHTTP would then access it using Expression Language 2 as in your example.