How can I get unique values in array in a jmespath query?

Question

In an aws cli jmespath query, with for example the output ["a","a","b","a","b"], how do i extract the unique values of it to get ["a","b"]?

score 16 · Accepted Answer · answered May 05 '16 at 17:49

16

Unfortunately this is not currently possible in jmespath.

answered May 05 '16 at 17:49

Jordon Phillips

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I would argue that jmespath is grep, not gawk. It just provides a selection of data. That is it's job. Processing json is someone else's business! :-) Now what that other tool should be is another question and I think the answer depends on context. – Max Murphy Feb 07 '17 at 12:41

score 7 · Answer 2 · answered Mar 05 '20 at 22:59

7

It's not what you asked for but I've used the following:

aws ... | jq -r ".[]" | sort | uniq

This will convert ["a", "a", "b", "a"] to:

a
b

answered Mar 05 '20 at 22:59

mekazu

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This is a great workaround. In PowerShell on Windows, I installed `jq` with `winget install stedolan.jq`. You may need the latest winget 1.4 `winget install winget`. Then `| jq -r ".[]" | sort` worked. – Cameron Taggart Apr 06 '23 at 04:21

score 0 · Answer 3 · answered Jan 09 '23 at 10:01

The closest I've come to "unique values"... is to deduplicate outside of JMESPath (so not really in JMESPath pipelines).

aws ec2 describe-images \
   --region us-east-1 \
   --filter "Name=architecture,Values=x86_64" \
   --query 'Images[].ImageOwnerAlias | join(`"\n"`, @)' \
   --output text \
| sort -u

Output:
amazon aws-marketplace

If you use JMESPath standalone, you'd write things like this.

jp -u -f myjson.json 'Images[].ImageOwnerAlias | join(`"\n"`, @)' | sort -u

The idea is to get jp to spit out a list of values (on separate lines) and then apply all the power of your favorite sorter. The tricky part is to get the list (of course).

How can I get unique values in array in a jmespath query?

3 Answers3