JMESPath to return as json

Question

JMESPath can be used to query json but the return is no longer json any more:

E.g., searching {"a": "foo", "b": "bar", "c": "baz"} with JMESPath a will yield "foo".

How can I return {"a": "foo"} instead?

jq is able to do it:

curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[0] | {message: .commit.message, name: .commit.committer.name}'

{
  "message": "Merge pull request #162 from stedolan/utf8-fixes\n\nUtf8 fixes. Closes #161",
  "name": "Stephen Dolan"
}

UPDATE:

I made returning {"a": "foo"} works but not for more complicates situation, like JMESPath query from AWS CLI to find EC2's security groups id and subnet id. I.e.,

• query 'Reservations[].Instances[].[InstanceId,NetworkInterfaces[].Groups[].GroupId,NetworkInterfaces[].SubnetId]' works, but when I tried to adapt it to
• query 'Reservations[].Instances[].{InstanceId: InstanceId, SubnetId: NetworkInterfaces[].Groups[].GroupId,NetworkInterfaces[].SubnetId}'

It then no longer working. Got error of:

Bad value for --query Reservations[].Instances[].{InstanceId: InstanceId, SubnetId: NetworkInterfaces[].Groups[].GroupId,NetworkInterfaces[].SubnetId}: Expecting: colon, got: flatten: Parse error at column 116, token "[]" (FLATTEN), for expression: "Reservations[].Instances[].{InstanceId: InstanceId, SubnetId: NetworkInterfaces[].Groups[].GroupId,NetworkInterfaces[].SubnetId}"

Is it the limitation of JMESPath or aws ec2 describe-instances command?

You can get the sample input from https://awscli.amazonaws.com/v2/documentation/api/2.0.34/reference/ec2/describe-instances.html, or better, from https://pastebin.com/JaFwn5ZH.

Answer 1

See MultiSelect Hash. For example,

>>> import jmespath
>>> expression = jmespath.compile('{a: a}')
>>> expression.search({"a": "foo", "b": "bar", "c": "baz"})
{'a': 'foo'}