Parentheses in JQ for .key

Question

I don\'t understand why key has to be in () for this to work:

# kbrandt at glade.local in ~ on git:master x [15:08:19]
$ cat host | jq \'. | to_         


        

Answer 1

When defining an object literal, the parentheses indicates that the expression value should be the property name. Otherwise if you didn't use parentheses, it's the literal name.

So these are equivalent ways to define an object with a "foo" property:

{ foo: 1 }
{ "foo": 2 }
"foo" as $name | { ($name): 3 }
{ somename: "foo" } | { (.somename): 4 }