如何检查json文件是否具有特定元素？

Question

How to check if ["foo"]["bar"] is present in a json file from BASH script? tried below:

$ cat myJson.json | if ( python3 -c "import sys,json; json.load(sys.stdin)['foo']['bar']"); then echo "found foo-bar"; fi
$ found foo-bar

it works, but it prints below if the element is not present:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
KeyError: 'baz'

but bash script don't fail anyway.

Update:

Tried try-except:

cat myJson.json | \
if (
python3 -c "
import sys,json
try:
   json.load(sys.stdin)['foo']['bar']
except KeyError:
   #exit with non-0.
   sys.exit(1)
") then echo "found foo_bar"; FOUND_FOO_BAR=true;
fi
echo $FOUND_FOO_BAR
$ found foo_bar
$ 
$

I am expecting "true" to be printed after `found foo_bar', but it doesn't, what am I doing wrong?

Answer 1

您可以使用jq工具：

jq 'map(has("foo.bar"))' myJson.json && echo "found foo-bar"