I'm looking for a solution to add a new attribute with a JSON object value into an existing JSON file.
My current script:
if [ ! -f "$src_file" ]; then
echo "Source file $src_file does not exists"
exit 1
fi
if [ ! -f "$dst_file" ]; then
echo "Destination file $dst_file does not exists"
exit 1
fi
if ! jq '.devDependencies' "$src_file" >/dev/null 2>&1; then
echo "The key "devDependencies" does not exists into source file $src_file"
exit 1
fi
dev_dependencies=$(jq '.devDependencies' "$src_file" | xargs )
# Extract data from source file
data=$(cat $src_file)
# Add new key-value
data=$(echo $data | jq --arg key "devDependencies" --arg value "$dev_dependencies" '. + {($key): ($value)}')
# Write data into destination file
echo $data > $dst_file
It's working but the devDependencies value from $dev_dependencies is wrote as string:
"devDependencies": "{ #nrwl/esbuild: 15.6.3, #nrwl/eslint-pl[...]".
How can I write it as raw JSON ?
I think you want the --argjson option instead of --arg. Compare
$ jq --arg k '{"foo": "bar"}' -n '{x: $k}'
{
"x": "{\"foo\": \"bar\"}"
}
with
$ jq --argjson k '{"foo": "bar"}' -n '{x: $k}'
{
"x": {
"foo": "bar"
}
}
--arg will create a string variable. Use --argjson to parse the value as JSON (can be object, array or number).
From the docs:
--arg name value:
This option passes a value to the jq program as a predefined variable.
If you run jq with --arg foo bar, then $foo is available in the
program and has the value "bar". Note that value will be treated as a
string, so --arg foo 123 will bind $foo to "123".
Named arguments are also available to the jq program as $ARGS.named.
--argjson name JSON-text:
This option passes a JSON-encoded value to the jq program as a
predefined variable. If you run jq with --argjson foo 123, then $foo
is available in the program and has the value 123.
Note that you don't need multiple invocations of jq, xargs, command substitution or variables (don't forget to quote all your variables when expanding).
To "merge" the contents of two files, read both files with jq and let jq do the work. This avoids all the complications that arise from jumping between jq and shell context. A single line is all that's needed:
jq --slurpfile deps "$dep_file" '. + { devDependencies: $deps[0].devDependencies }' "$source_file" > "$dest_file"
or
jq --slurpfile deps "$dep_file" '. + ($deps[0]|{devDependencies})' "$source_file" > "$dest_file"
alternatively (still a one-liner):
jq --slurpfile deps "$dev_file" '.devDependencies = $deps[0].devDependencies' "$source_file" > "$dest_file"
peak's answer here reminded me of the very useful input filter, which can make the program even shorter as it avoids the variable:
jq '. + (input|{devDependencies})' "$source_file" "$dep_file" > "$dest_file"
I have a .json file which I want to read, take all the contents.. and append it to a json string that's in a bash variable
input.json
[{
"maven": {
"coordinates": "somelib",
"repo": "somerepo"
}
},
{
"maven": {
"coordinates": "anotherlib",
"exclusions": ["exclude:this", "*:and-all-that"]
}
}]
OUR_BIG_JSON variable
{
"name": "",
"myarray": [
{
"generic": {
"package": "somepymodule"
}
},
{
"rcann": {
"package": "anothermodule==3.0.0"
}
}
],
and a json I want to append to.. it's residing in a variable so we must echo it as we use jq
command attempt
echo "starting..."
inputs_json=`cat input.json`
echo "$inputs_json"
echo "$OUR_BIG_JSON"
OUR_BIG_JSON=$(echo "${OUR_BIG_JSON}" |./jq '.myarray += [{"date":"today"}]') # This worked..
next line fails
OUR_BIG_JSON=$(echo "${OUR_BIG_JSON}" |./jq '.myarray += ' $inputs_json)
out comes errors when trying to take the $inputs_json contents and just pipe it into the variable.. basically append to the JSON in memory..
jq: error: syntax error, unexpected INVALID_CHARACTER (Windows cmd shell quoting issues?) at <top-level>, line 1: .myarray += \"$inputs_json\" jq: 1 compile error
Using the --argjson option to read in the contents of your shell variable enables you to use it as variable inside the jq filter, too. Your input file can normally be read in via parameter.
jq --argjson v "${OUR_BIG_JSON}" '…your filter here using $v…' input.json
For example:
jq --argjson v "${OUR_BIG_JSON}" '$v + {myarray: ($v.myarray + .)}' input.json
Or by making the input too a variable inside the jq filter
jq --argjson v "${OUR_BIG_JSON}" '. as $in | $v | .myarray += $in' input.json
With the -n option you could also reference the input using input:
jq --argjson v "${OUR_BIG_JSON}" -n '$v | .myarray += input' input.json
And there's also the options --argfile and --slurpfile to read in the input file as variable directly...
As you have tagged bash you could also do it the other way around and use a herestring <<< to read in the bash variable as input and then using either --argfile or --slurpfile to reference the file content through a variable. For instance:
jq --argfile in input.json '.myarray += $in' <<< "${OUR_BIG_JSON}"
Trying to write a bash script that replaces values in a JSON file we are running into issues with Environment Variables that contain whitespaces.
Given an original JSON file.
{
"version": "base",
"myValue": "to be changed",
"channelId": 0
}
We want to run a command to update some variables in it, so that after we run:
CHANNEL_ID=1701 MY_VALUE="new value" ./test.sh
The JSON should look like this:
{
"version": "base",
"myValue": "new value",
"channelId": 1701
}
Our script is currently at something like this:
#!/bin/sh
echo $MY_VALUE
echo $CHANNEL_ID
function replaceValue {
if [ -z $2 ]; then echo "Skipping $1"; else jq --argjson newValue \"${2}\" '. | ."'${1}'" = $newValue' build/config.json > tmp.json && mv tmp.json build/config.json; fi
}
replaceValue channelId ${CHANNEL_ID}
replaceValue myValue ${MY_VALUE}
In the above all values are replaced by string and strings are getting truncated at whitespace. We keep alternating between this issue and a version of the code where substitutions just stop working entirely.
This is surely an issue with expansions but we would love to figure out, how we can:
- Replace values in the JSON with both strings and values.
- Use whitespaces in the strings we pass to our script.
You don't have to mess with --arg or --argjson to import the environment variables into jq's context. It can very well read the environment on its own. You don't need a script separately, just set the values along with the invocation of jq
CHANNEL_ID=1701 MY_VALUE="new value" \
jq '{"version": "base", myValue: env.MY_VALUE, channelId: env.CHANNEL_ID}' build/config.json
Note that in the case above, the variables need not be exported globally but just locally to the jq command. This allows you to not export multiple variables into the shell and pollute the environment, but just the ones needed for jq to construct the desired JSON.
To make the changes back to the original file, do > tmp.json && mv tmp.json build/config.json or more clearly download the sponge(1) utility from moreutils package. If present, you can pipe the output of jq as
| sponge build/config.json
Pass variables with --arg. Do:
jq --arg key "$1" --arg value "$2" '.[$key] = $value'
Notes:
#!/bin/sh indicates that this is posix shell script, not bash. Use #!/bin/bash in bash scripts.
function replaceValue { is something from ksh shell. Prefer replaceValue() { to declare functions. Bash obsolete and deprecated syntax.
Use newlines in your script to make it readable.
--argjson passes a json formatted argument, not a string. Use --arg for that.
\"${2}\" doesn't quote $2 expansion - it only appends and suffixes the string with ". Because the expansion is not qouted, word splitting is performed, which causes your input to be split on whitespaces when creating arguments for jq.
Remember to quote variable expansions.
Use http://shellcheck.net to check your scripts.
. | means nothing in jq, it's like echo $(echo $(echo))). You could jq '. | . | . | . | . | .' do it infinite number of times - it passes the same thing. Just write the thing you want to do.
Do:
#!/bin/bash
echo "$MY_VALUE"
echo "$CHANNEL_ID"
replaceValue() {
if [ -z "$2" ]; then
echo "Skipping $1"
else
jq --arg key "$1" --arg value "$2" '.[$key] = $value' build/config.json > tmp.json &&
mv tmp.json build/config.json
fi
}
replaceValue channelId "${CHANNEL_ID}"
replaceValue myValue "${MY_VALUE}"
#edit Replaced ."\($key)" with easier .[$key]
jq allows you to build new objects:
MY_VALUE=foo;
CHANNEL_ID=4
echo '{
"version": "base",
"myValue": "to be changed",
"channelId": 0
}' | jq ". | {\"version\": .version, \"myValue\": \"$MY_VALUE\", \"channelId\": $CHANNEL_ID}"
The . selects the whole input, and inputs that (|) to the construction of a new object (marked by {}). For version is selects .version from the input, but you can set your own values for the other two. We use double quotes to allow the Bash variable expansion, which means escaping the double quotes in the JSON.
You'll need to adapt my snippet above to scriptify it.
I need to read these bash variables into my JSON string and I am not familiar with bash. any help is appreciated.
#!/bin/sh
BUCKET_NAME=testbucket
OBJECT_NAME=testworkflow-2.0.1.jar
TARGET_LOCATION=/opt/test/testworkflow-2.0.1.jar
JSON_STRING='{"bucketname":"$BUCKET_NAME"","objectname":"$OBJECT_NAME","targetlocation":"$TARGET_LOCATION"}'
echo $JSON_STRING
You are better off using a program like jq to generate the JSON, if you don't know ahead of time if the contents of the variables are properly escaped for inclusion in JSON. Otherwise, you will just end up with invalid JSON for your trouble.
BUCKET_NAME=testbucket
OBJECT_NAME=testworkflow-2.0.1.jar
TARGET_LOCATION=/opt/test/testworkflow-2.0.1.jar
JSON_STRING=$( jq -n \
--arg bn "$BUCKET_NAME" \
--arg on "$OBJECT_NAME" \
--arg tl "$TARGET_LOCATION" \
'{bucketname: $bn, objectname: $on, targetlocation: $tl}' )
You can use printf:
JSON_FMT='{"bucketname":"%s","objectname":"%s","targetlocation":"%s"}\n'
printf "$JSON_FMT" "$BUCKET_NAME" "$OBJECT_NAME" "$TARGET_LOCATION"
much clear and simpler
A possibility:
#!/bin/bash
BUCKET_NAME="testbucket"
OBJECT_NAME="testworkflow-2.0.1.jar"
TARGET_LOCATION="/opt/test/testworkflow-2.0.1.jar
# one line
JSON_STRING='{"bucketname":"'"$BUCKET_NAME"'","objectname":"'"$OBJECT_NAME"'","targetlocation":"'"$TARGET_LOCATION"'"}'
# multi-line
JSON_STRING="{
\"bucketname\":\"${BUCKET_NAME}\",
\"objectname\":\"${OBJECT_NAME}\",
\"targetlocation\":\"${TARGET_LOCATION}\"
}"
# [optional] validate the string is valid json
echo "${JSON_STRING}" | jq
In addition to chepner's answer, it's also possible to construct the object completely from args with this simple recipe:
BUCKET_NAME=testbucket
OBJECT_NAME=testworkflow-2.0.1.jar
TARGET_LOCATION=/opt/test/testworkflow-2.0.1.jar
JSON_STRING=$(jq -n \
--arg bucketname "$BUCKET_NAME" \
--arg objectname "$OBJECT_NAME" \
--arg targetlocation "$TARGET_LOCATION" \
'$ARGS.named')
Explanation:
--null-input | -n disabled reading input. From the man page: Don't read any input at all! Instead, the filter is run once using null as the input. This is useful when using jq as a simple calculator or to construct JSON data from scratch.
--arg name value passes values to the program as predefined variables: value is available as $name. All named arguments are also available as $ARGS.named
Because the format of $ARGS.named is already an object, jq can output it as is.
First, don't use ALL_CAPS_VARNAMES: it's too easy to accidentally overwrite a crucial shell variable (like PATH)
Mixing single and double quotes in shell strings can be a hassle. In this case, I'd use printf:
bucket_name=testbucket
object_name=testworkflow-2.0.1.jar
target_location=/opt/test/testworkflow-2.0.1.jar
template='{"bucketname":"%s","objectname":"%s","targetlocation":"%s"}'
json_string=$(printf "$template" "$BUCKET_NAME" "$OBJECT_NAME" "$TARGET_LOCATION")
echo "$json_string"
For homework, read this page carefully: Security implications of forgetting to quote a variable in bash/POSIX shells
A note on creating JSON with string concatenation: there are edge cases. For example, if any of your strings contain double quotes, you can broken JSON:
$ bucket_name='a "string with quotes"'
$ printf '{"bucket":"%s"}\n' "$bucket_name"
{"bucket":"a "string with quotes""}
Do do this more safely with bash, we need to escape that string's double quotes:
$ printf '{"bucket":"%s"}\n' "${bucket_name//\"/\\\"}"
{"bucket":"a \"string with quotes\""}
I had to work out all possible ways to deal json strings in a command request, Please look at the following code to see why using single quotes can fail if used incorrectly.
# Create Release and Tag commit in Github repository
# returns string with in-place substituted variables
json=$(cat <<-END
{
"tag_name": "${version}",
"target_commitish": "${branch}",
"name": "${title}",
"body": "${notes}",
"draft": ${is_draft},
"prerelease": ${is_prerelease}
}
END
)
# returns raw string without any substitutions
# single or double quoted delimiter - check HEREDOC specs
json=$(cat <<-!"END" # or 'END'
{
"tag_name": "${version}",
"target_commitish": "${branch}",
"name": "${title}",
"body": "${notes}",
"draft": ${is_draft},
"prerelease": ${is_prerelease}
}
END
)
# prints fully formatted string with substituted variables as follows:
echo "${json}"
{
"tag_name" : "My_tag",
"target_commitish":"My_branch"
....
}
Note 1: Use of single vs double quotes
# enclosing in single quotes means no variable substitution
# (treats everything as raw char literals)
echo '${json}'
${json}
echo '"${json}"'
"${json}"
# enclosing in single quotes and outer double quotes causes
# variable expansion surrounded by single quotes(treated as raw char literals).
echo "'${json}'"
'{
"tag_name" : "My_tag",
"target_commitish":"My_branch"
....
}'
Note 2: Caution with Line terminators
Note the json string is formatted with line terminators such as LF \n
or carriage return \r(if its encoded on windows it contains CRLF \r\n)
using (translate) tr utility from shell we can remove the line terminators if any
# following code serializes json and removes any line terminators
# in substituted value/object variables too
json=$(echo "$json" | tr -d '\n' | tr -d '\r' )
# string enclosed in single quotes are still raw literals
echo '${json}'
${json}
echo '"${json}"'
"${json}"
# After CRLF/LF are removed
echo "'${json}'"
'{ "tag_name" : "My_tag", "target_commitish":"My_branch" .... }'
Note 3: Formatting
while manipulating json string with variables, we can use combination of ' and " such as following, if we want to protect some raw literals using outer double quotes to have in place substirution/string interpolation:
# mixing ' and "
username=admin
password=pass
echo "$username:$password"
admin:pass
echo "$username"':'"$password"
admin:pass
echo "$username"'[${delimiter}]'"$password"
admin[${delimiter}]pass
Note 4: Using in a command
Following curl request already removes existing \n (ie serializes json)
response=$(curl -i \
--user ${username}:${api_token} \
-X POST \
-H 'Accept: application/vnd.github.v3+json' \
-d "$json" \
"https://api.github.com/repos/${username}/${repository}/releases" \
--output /dev/null \
--write-out "%{http_code}" \
--silent
)
So when using it for command variables, validate if it is properly formatted before using it :)
If you need to build a JSON representation where members mapped to undefined or empty variables should be ommited, then jo can help.
#!/bin/bash
BUCKET_NAME=testbucket
OBJECT_NAME=""
JO_OPTS=()
if [[ ! "${BUCKET_NAME}x" = "x" ]] ; then
JO_OPTS+=("bucketname=${BUCKET_NAME}")
fi
if [[ ! "${OBJECT_NAME}x" = "x" ]] ; then
JO_OPTS+=("objectname=${OBJECT_NAME}")
fi
if [[ ! "${TARGET_LOCATION}x" = "x" ]] ; then
JO_OPTS+=("targetlocation=${TARGET_LOCATION}")
fi
jo "${JO_OPTS[#]}"
The output of the commands above would be just (note the absence of objectname and targetlocation members):
{"bucketname":"testbucket"}
can be done following way:
JSON_STRING='{"bucketname":"'$BUCKET_NAME'","objectname":"'$OBJECT_NAME'","targetlocation":"'$TARGET_LOCATION'"}'
For Node.js Developer, or if you have node environment installed, you can try this:
JSON_STRING=$(node -e "console.log(JSON.stringify({bucketname: $BUCKET_NAME, objectname: $OBJECT_NAME, targetlocation: $TARGET_LOCATION}))")
Advantage of this method is you can easily convert very complicated JSON Object (like object contains array, or if you need int value instead of string) to JSON String without worrying about invalid json error.
Disadvantage is it's relying on Node.js environment.
These solutions come a little late but I think they are inherently simpler that previous suggestions (avoiding the complications of quoting and escaping).
BUCKET_NAME=testbucket
OBJECT_NAME=testworkflow-2.0.1.jar
TARGET_LOCATION=/opt/test/testworkflow-2.0.1.jar
# Initial unsuccessful solution
JSON_STRING='{"bucketname":"$BUCKET_NAME","objectname":"$OBJECT_NAME","targetlocation":"$TARGET_LOCATION"}'
echo $JSON_STRING
# If your substitution variables have NO whitespace this is sufficient
JSON_STRING=$(tr -d [:space:] <<JSON
{"bucketname":"$BUCKET_NAME","objectname":"$OBJECT_NAME","targetlocation":"$TARGET_LOCATION"}
JSON
)
echo $JSON_STRING
# If your substitution variables are more general and maybe have whitespace this works
JSON_STRING=$(jq -c . <<JSON
{"bucketname":"$BUCKET_NAME","objectname":"$OBJECT_NAME","targetlocation":"$TARGET_LOCATION"}
JSON
)
echo $JSON_STRING
#... A change in layout could also make it more maintainable
JSON_STRING=$(jq -c . <<JSON
{
"bucketname" : "$BUCKET_NAME",
"objectname" : "$OBJECT_NAME",
"targetlocation" : "$TARGET_LOCATION"
}
JSON
)
echo $JSON_STRING
To build upon Hao's answer using NodeJS: you can split up the lines, and use the -p option which saves having to use console.log.
JSON_STRING=$(node -pe "
JSON.stringify({
bucketname: process.env.BUCKET_NAME,
objectname: process.env.OBJECT_NAME,
targetlocation: process.env.TARGET_LOCATION
});
")
An inconvenience is that you need to export the variables beforehand, i.e.
export BUCKET_NAME=testbucket
# etc.
Note: You might be thinking, why use process.env? Why not just use single quotes and have bucketname: '$BUCKET_NAME', etc so bash inserts the variables? The reason is that using process.env is safer - if you don't have control over the contents of $TARGET_LOCATION it could inject JavaScript into your node command and do malicious things (by closing the single quote, e.g. the $TARGET_LOCATION string contents could be '}); /* Here I can run commands to delete files! */; console.log({'a': 'b. On the other hand, process.env takes care of sanitising the input.
You could use envsubst:
export VAR="some_value_here"
echo '{"test":"$VAR"}' | envsubst > json.json
also it might be a "template" file:
//json.template
{"var": "$VALUE", "another_var":"$ANOTHER_VALUE"}
So after you could do:
export VALUE="some_value_here"
export ANOTHER_VALUE="something_else"
cat json.template | envsubst > misha.json
For a general case of building JSON from bash with arbitrary inputs, many of the previous responses (even the high voted ones with jq) omit cases when the variables contain " double quote, or \n newline escape string, and you need complex string concatenation of the inputs.
When using jq you need to printf %b the input first to get the \n converted to real newlines, so that once you pass through jq you get \n back and not \\n.
I found this with version with nodejs to be quite easy to reason about if you know javascript/nodejs well:
TITLE='Title'
AUTHOR='Bob'
JSON=$( TITLE="$TITLE" AUTHOR="$AUTHOR" node -p 'JSON.stringify( {"message": `Title: ${process.env.TITLE}\n\nAuthor: ${process.env.AUTHOR}`} )' )
It's a bit verbose due to process.env. but allows to properly pass the variables from shell, and then format things inside (nodejs) backticks in a safe way.
This outputs:
printf "%s\n" "$JSON"
{"message":"Title: Title\n\nAuthor: Bob"}
(Note: when having a variable with \n always use printf "%s\n" "$VAR" and not echo "$VAR", whose output is platform-dependent! See here for details)
Similar thing with jq would be
TITLE='Title'
AUTHOR='Bob'
MESSAGE="Title: ${TITLE}\n\nAuthor: ${AUTHOR}"
MESSAGE_ESCAPED_FOR_JQ=$(printf %b "${MESSAGE}")
JSON=$( jq '{"message": $jq_msg}' --arg jq_msg "$MESSAGE_ESCAPED_FOR_JQ" --null-input --compact-output --raw-output --monochrome-output )
(the last two params are not necessary when running in a subshell, but I just added them so that the output is then same when you run the jq command in a top-level shell).
Bash will not insert variables into a single-quote string. In order to get the variables bash needs a double-quote string.
You need to use double-quote string for the JSON and just escape double-quote characters inside JSON string.
Example:
#!/bin/sh
BUCKET_NAME=testbucket
OBJECT_NAME=testworkflow-2.0.1.jar
TARGET_LOCATION=/opt/test/testworkflow-2.0.1.jar
JSON_STRING="{\"bucketname\":\"$BUCKET_NAME\",\"objectname\":\"$OBJECT_NAME\",\"targetlocation\":\"$TARGET_LOCATION\"}"
echo $JSON_STRING
if you have node.js and get minimist installed in global:
jc() {
node -p "JSON.stringify(require('minimist')(process.argv), (k,v) => k=='_'?undefined:v)" -- "$#"
}
jc --key1 foo --number 12 --boolean \
--under_score 'abc def' --'white space' ' '
# {"key1":"foo","number":12,"boolean":true,"under_score":"abc def","white space":" "}
you can post it with curl or what:
curl --data "$(jc --type message --value 'hello world!')" \
--header 'content-type: application/json' \
http://server.ip/api/endpoint
be careful that minimist will parse dot:
jc --m.room.member #gholk:ccns.io
# {"m":{"room":{"member":"#gholk:ccns.io"}}}
Used this for AWS Macie configuration:
JSON_CONFIG=$( jq -n \
--arg bucket_name "$BUCKET_NAME" \
--arg kms_key_arn "$KMS_KEY_ARN" \
'{"s3Destination":{"bucketName":$bucket_name,"kmsKeyArn":$kms_key_arn}}'
)
aws macie2 put-classification-export-configuration --configuration "$JSON_CONFIG"
You can simply make a call like this to print the JSON.
#!/bin/sh
BUCKET_NAME=testbucket
OBJECT_NAME=testworkflow-2.0.1.jar
TARGET_LOCATION=/opt/test/testworkflow-2.0.1.jar
echo '{ "bucketName": "'"$BUCKET_NAME"'", "objectName": "'"$OBJECT_NAME"'", "targetLocation": "'"$TARGET_LOCATION"'" }'
or
JSON_STRING='{ "bucketName": "'"$BUCKET_NAME"'", "objectName": "'"$OBJECT_NAME"'", "targetLocation": "'"$TARGET_LOCATION"'" }'
echo $JOSN_STRING
As a follow-up to Flatten Arbitrary JSON, I'm looking to take the flattened results and make them suitable for doing queries and updates back to the original JSON file.
Motivation: I'm writing Bash (4.2+) scripts (on CentOS 7) that read JSON into a Bash associative array using the JSON selector/filter as the key. I do processing on the associative arrays, and in the end I want to update the JSON with those changes.
The preceding solution gets me close to this goal. I think there are two things that it doesn't do:
It doesn't quote keys that require quoting. For example, the key com.acme would need to be quoted because it contains a special character.
Array indexes are not represented in a form that can be used to query the original JSON.
Existing Solution
The solution from the above is:
$ jq --stream -n --arg delim '.' 'reduce (inputs|select(length==2)) as $i ({};
[$i[0][]|tostring] as $path_as_strings
| ($path_as_strings|join($delim)) as $key
| $i[1] as $value
| .[$key] = $value
)' input.json
For example, if input.json contains:
{
"a.b":
[
"value"
]
}
then the output is:
{
"a.b.0": "value"
}
What is Really Wanted
An improvement would have been:
{
"\"a.b\"[0]": "value"
}
But what I really want is output formatted so that it could be sourced directly in a Bash program (implying the array name is passed to jq as an argument):
ArrayName['"a.b"[0]']='value' # Note 'value' might need escapes for Bash
I'm looking to have the more human-readable syntax above as opposed to the more general:
ArrayName['.["a.b"][0]']='value'
I don't know if jq can handle all of this. My present solution is to take the output from the preceding solution and to post-process it to the form that I want. Here's the work in process:
#!/bin/bash
Flatten()
{
local -r OPTIONS=$(getopt -o d:m:f: -l "delimiter:,mapname:,file:" -n "${FUNCNAME[0]}" -- "$#")
eval set -- "$OPTIONS"
local Delimiter='.' MapName=map File=
while true ; do
case "$1" in
-d|--delimiter) Delimiter="$2"; shift 2;;
-m|--mapname) MapName="$2"; shift 2;;
-f|--file) File="$2"; shift 2;;
--) shift; break;;
esac
done
local -a Array=()
readarray -t Array <<<"$(
jq -c -S --stream -n --arg delim "$Delimiter" 'reduce (inputs|select(length==2)) as $i ({}; .[[$i[0][]|tostring]|join($delim)] = $i[1])' <<<"$(sed 's|^\s*[#%].*||' "$File")" |
jq -c "to_entries|map(\"\(.key)=\(.value|tostring)\")|.[]" |
sed -e 's|^"||' -e 's|"$||' -e 's|=|\t|')"
if [[ ! -v $MapName ]]; then
local -gA $MapName
fi
. <(
IFS=$'\t'
while read -r Key Value; do
printf "$MapName[\"%s\"]=%q\n" "$Key" "$Value"
done <<<"$(printf "%s\n" "${Array[#]}")"
)
}
declare -A Map
Flatten -m Map -f "$1"
declare -p Map
With the output:
$ ./Flatten.sh <(echo '{"a.b":["value"]}')
declare -A Map='([a.b.0]="value" )'
1) jq is Turing complete, so it's all just a question of which hammer to use.
2)
An improvement would have been:
{
"\"a.b\"[0]": "value"
}
That is easily accomplished using a helper function along these lines:
def flattenPath(delim):
reduce .[] as $s ("";
if $s|type == "number"
then ((if . == "" then "." else . end) + "[\($s)]")
else . + ($s | tostring | if index(delim) then "\"\(.)\"" else . end)
end );
3)
I do processing on the associative arrays, and in the end I want to update the JSON with those changes.
This suggests you might have posed an xy-problem. However, if you really do want to serialize and unserialize some JSON text, then the natural way to do so using jq is using leaf_paths, as illustrated by the following serialization/deserialization functions:
# Emit (path, value) pairs
# Usage: jq -c -f serialize.jq input.json > serialized.json
def serialize: leaf_paths as $p | ($p, getpath($p));
# Usage: jq -n -f unserialize.jq serialized.json
def unserialize:
def pairwise(s):
foreach s as $i ([];
if length == 1 then . + [$i] else [$i] end;
select(length == 2));
reduce pairwise(inputs) as $p (null; setpath($p[0]; $p[1]));
If using bash, you could use readarray (mapfile) to read the paths and values into a single array, or if you want to distinguish between the paths and values more easily, you could (for example) use the approach illustrated by the following:
i=0
while read -r line ; do
path[$i]="$line"; read -r line; value[$i]="$line"
i=$((i + 1))
done < serialized.json
But there are many other alternatives.