I`m trying to do a bash script for a checkpoint management server api and I am experiencing some problems.
I want to get the value in a json dictionary and for that I have to use variables. I am entering this command:
echo $rulebase | jq --arg n "$0" '.rulebase[$n].to'
and I get the next error:
jq: error: Cannot index array with string
However, If i use :
echo $rulebase | jq '.rulebase[0].to'
I get the result that I need. I dont know how to use the variables when they are a number, can anyone help me?
You need to convert the string that you give to your script to a number.
echo "$rulebase" | jq --arg n "$1" '.rulebase[$n|tonumber].to'
If you want to pass in a numeric value, use
—-argjson
instead of —-arg, which is for JSON string values.
If your jq does not support —argjson, then now would be an excellent time to upgrade if possible; otherwise, you could use tonumber.
If you have the index number in $0, just let the shell insert it by using appropriate quotes:
echo $rulebase | jq ".rulebase[$0].to"
(this being strange, having a number in $0, which normally is the program name).
You need to pass numbers as JSON args. Here
echo "$rulebase" | jq --argjson n "$my_variable" '.rulebase[$n].to'
Related
I see questions about selecting multiple values from an array using JQ, but I have a string that originally I just need the value after the last /, which is easily selected:
Input:
https://www.googleapis.com/compute/v1/projects/test-project-1/zones/europe-west1-b/instanceGroups/test-instance-group-1
JQ:
jq -r '.[]|.zone|=split("/")[-1]|"\(.name) \(.zone)"'
Output:
test-instance-group-1 europe-west1-b
However for the actual instances, the zone isn't listed, so must be extracted from the same key instance.
Input:
https://www.googleapis.com/compute/v1/projects/test-project-1/zones/europe-west1-b/instances/test-instance-1
JQ:
jq -r '.[]|.instance|=split("/")[-1]|"\(.instance)'
Output:
test-instance-1
However, I also want to extract the zone infomation, from the input as well, which I presume is selected with =split("/")[-3] however no matter how I format the request to JQ, I get errors:
$ jq -r '.[]|.instance|=split("/")[-1][-3]|"\(.instance)"'
jq: error (at <stdin>:47): Cannot index string with number
How can I extract two strings, from the same value/key ?
You're looking for something like this:
jq -r '.[].instance | split("/") | "\(.[-1]) \(.[-3])"'
I would like to write a simple jq file that allows me to count items grouped by a specified key.
I expect the script contents to be something similar too:
group_by($group) | map({group: $group, cnt: length})
and to invoke it something like
cat my.json | jq --from-file count_by.jq --args group .header.messageType
Whatever I've tried the argument always ends up as a string and is not usable as a key.
Since you have not followed the minimal complete verifiable example
guidelines, it's a bit difficult to know what the best approach to your problem will be, but whatever approach you take, it is important to bear in mind that --arg always passes in a JSON string. It cannot be used to pass in a jq program fragment unless the fragment is a JSON string.
So let's consider one option: passing in a JSON object representing a path that you can use in your program.
So the invocation could be:
jq -f count_by.jq --argjson group '["header", "messageType"]'
and the program would begin with:
group_by(getpath($group)) | ...
Having your cake ...
If you really want to pass in arguments such as .header.messageType, there is a way: convert the string $group into a jq path:
($group|split(".")|map(select(length>0))) as $path
So your jq filter would look like this:
($group|split(".")|map(select(length>0))) as $path
| group_by(getpath($path)) | map({group: $group, cnt: length})
Shell string interpolation
If you want a quick bash solution that comes with many caveats:
group=".header.messageType"
jq 'group_by('"$group"') | map({group: "'"$group"'", cnt: length}'
I'm trying to use jq to get a value from the JSON that cURL returns.
This is the JSON cURL passes to jq (and, FTR, I want jq to return "VALUE-I-WANT" without the quotation marks):
[
{
"success":{
"username":"VALUE-I-WANT"
}
}
]
I initially tried this:
jq ' . | .success | .username'
and got
jq: error (at <stdin>:0): Cannot index array with string "success"
I then tried a bunch of variations, with no luck.
With a bunch of searching the web, I found this SE entry, and thought it might have been my saviour (spoiler, it wasn't). But it led me to try these:
jq -r '.[].success.username'
jq -r '.[].success'
They didn't return an error, they returned "null". Which may or may not be an improvement.
Can anybody tell me what I'm doing wrong here? And why it's wrong?
You need to pipe the output of .[] into the next filter.
jq -r '.[] | .success.username' tmp.json
tl;dr
# Extract .success.username from ALL array elements.
# .[] enumerates all array elements
# -r produces raw (unquoted) output
jq -r '.[].success.username' file.json
# Extract .success.username only from the 1st array element.
jq -r '.[0].success.username' file.json
Your input is an array, so in order to access its elements you need .[], the array/object-value iterator (as the name suggests, it can also enumerate the properties of an object):
Just . | sends the input (.) array as a whole through the pipeline, and an array only has numerical indices, so the attempt to index (access) it with .success.username fails.
Thus, simply replacing . | with .[] | in your original attempt, combined with -r to get raw (unquoted output), should solve your problem, as shown in chepner's helpful answer.
However, peak points out that since at least jq 1.3 (current as of this writing is jq 1.5) you don't strictly need a pipeline, as demonstrated in the commands at the top.
So the 2nd command in your question should work with your sample input, unless you're using an older version.
I'm using jq to parse some of my logs, but some of the log lines can't be parsed for various reasons. Is there a way to have jq ignore those lines? I can't seem to find a solution. I tried to use the --seq argument that was recommended by some people, but --seq ignores all the lines in my file.
Assuming that each log entry is exactly one line, you can use the -R or --raw-input option to tell jq to leave the lines unparsed, after which you can prepend fromjson? | to your filter to make jq try to parse each line as JSON and throw away the ones that error.
I have log stream where some messages are in json format.
I want to pipe the json messages through jq, and just echo the rest.
The json messages are on a single line.
Solution: use grep and tee to split the lines in two streams, those starting with "^{" pipe through jq and the rest just echo to terminal.
kubectl logs -f web-svjkn | tee >(grep -v "^{") | grep "^{" | jq .
or
cat logs | tee >(grep -v "^{") | grep "^{" | jq .
Explanation:
tee generates 2nd stream, and grep -v prints non json info, 2nd grep only pipes what looks like json opening bracket to jq.
This is an old thread, but here's another solution fully in jq. This allows you to both process proper json lines and also print out non-json lines.
jq -R . as $line | try (fromjson | <further processing for proper json lines>) catch $line'
There are several Q&As on the FAQ page dealing with the topic of "invalid JSON", but see in particular the Q:
Is there a way to have jq keep going after it hits an error in the input file?
In particular, this shows how to use --seq.
However, from the the sparse details you've given (SO recommends a minimal example be given), it would seem it might be better simply to use inputs. The idea is to process one JSON entity at a time, using "try/catch", e.g.
def handle: inputs | [., "length is \(length)"] ;
def process: try handle catch ("Failed", process) ;
process
Don't forget to use the -n option when invoking jq.
See also Processing not-quite-valid JSON.
If JSON in curly braces {}:
grep -Pzo '\{(?>[^\{\}]|(?R))*\}' | jq 'objects'
If JSON in square brackets []:
grep -Pzo '\[(?>[^\[\]]|(?R))*\]' | jq 'arrays'
This works if there are no []{} in non-JSON lines.
I have to curl to a site (statuscake.com) that sends multiple items back in a JSON, each line of which contains multiple items. I want to extract from each line two of them, WebsiteName and TestID, so I can check if WebsiteName matches the one I'm interested in, get the TestID out and pass this to a second curl statement to delete the test.
Although it's more complex, the JSON that comes back is essentially of the form
[{"TestID": 123, "WebsiteName": "SomeSite1"}, {"TestID": 1234, "WebsiteName": "SomeSite2"}]
I can't seem to find a magic jq command to do it all in one - if there is one, I'd be really happy to see it.
I've got
cat $data | jq '[.[] | .WebsiteName]'
to get an array of the website names (and a very similar one for the TestIDs, but I think I've done something daft. data is the information coming back from the curl to get the JSON and that's populated OK.
I want to be able to assign these to two arrays, names and ids, then search names for the index of the relevant name, grab the id from ids and pass that to the curl. Unless there's a better way.
Any advice please?
My Xidel can do it all at once by selecting the JSON with a XPath-like query:
E.g. return all ids where the WebsiteName contains "site2" from an array of objects:
xidel /tmp/x.json -e '$json()[contains((.).WebsiteName, "site2")]/TestID'
Or e.g. to download the original JSON and then make the HTTP request with the ids:
xidel http://statuscake.com/your-url... -f '$json()[contains((.).WebsiteName, "site2")]/TestID!x"/your-delete-url{.}..."'
If I'm getting your question right, it sounds like what you want is to, for each element, select those where .WebsiteName == "needle", and then get .TestID from it. You can do just that:
.[] | select(.WebsiteName == "needle") | .TestID
If you want an array as the result, you can wrap the above script in square brackets.
The jq filters startswith and endswith may be of interest to you. If you're going to pass the result back to cURL, you may also be interested in the #sh formatting filter and the -r command-line flag.
Assuming you have a bash 4+ and assuming the json is valid (does not contain newlines in strings, etc.) this works:
$ echo "$data"
[{"TestID": 123, "WebsiteName": "SomeSite1"}, {"TestID": 1234, "WebsiteName":
"SomeSite2"}, {"TestID": 555, "WebsiteName": "foo*ba#r blah[54]quux{4,5,6}"}]
$ declare -A arr
$ while IFS= read -r line; do
eval "$line"
done < <(jq -M -r '.[] | #sh "arr[\(.WebsiteName)]+=\(.TestID)"' <<<"$data")
$ declare -p arr
declare -A arr='(["foo*ba#r blah[54]quux{4,5,6}"]="555" [SomeSite2]="1234" [SomeSite1]="123" )'
Here is a solution using only jq primitives.
.[]
| if .WebsiteName == "SomeSite1" then .TestID else empty end
This is essentially the same as Santiago's answer but if you are new to jq it may be informative because select/1 is defined as
def select(f): if f then . else empty end;