My Google search skills are failing me. How to get a list of all JSON object keys in JMESPath?
i.e. how to go from:
{"a": 1, "b": 2}
to:
["a", "b"]
JMESPath has the function keys. Therefore, the JMESPath expression is keys(#).
Example
echo '{"a": 1, "b": 2}' | jp "keys(#)"
returns
[
"a",
"b"
]
Tested with jp 0.1.3 on a Linux environment.
Related
I'm using MySQL 5.7.12, and have a JSON column with the following data:
[{"tpe": "I", "val": 1}, {"tpe": "C", "val": 2}, {"tpe": "A", "val": 3}]
I would like to UPDATE val from 2 into 20 WHERE tpe='C'.
Here is my attempt:
UPDATE user SET data = JSON_SET(data->"$[1]", '$.val', 20);
This does update the value but it trims the other elements in the array and it becomes only a json-object, here how it looks after the update:
{"tpe": "C", "val": 20}
How can I get this right?
2nd question: is there a way to dynamically get the json object in the array so I don't have to hard code "$[1]" ? I tried to use JSON_SEARCH ??
I am trying to count all elements in a nested JSON-document with jq?
Given the following JSON-document
{"a": true, "b": [1, 2], "c": {"a": {"aa":1, "bb": 2}, "b": "blue"}}
I want to calculate the result 6.
In order to do this, I tried the following:
echo '{"a": true, "b": [1, 2], "c": {"a": {"aa":1, "bb": 2}, "b": "blue"}}' \
| jq 'reduce (.. | if (type == "object" or type == "array")
then length else 0 end) as $counts
(1; . + $counts)'
# Actual output: 10
# Desired output: 6
However, this counts the encountered objects and arrays as well and therefore yields 10 opposing to the desired output: 6
So, how can I only count the document's elements/leaf-nodes?
Thanks already in advance for you help!
Edit: What would be an efficient approach to count empty arrays and objects as well?
You can use the scalars filter to find leaf nodes. Scalars are all "simple" JSON values, i.e. null, true, false, numbers and strings. Alternatively you can compare the type of each item and use length to determine if an object or array has children.
I've expanded your input data a little to distinguish a few more corner cases:
Input:
{
"a": true,
"b": [1, 2],
"c": {
"a": {
"aa": 1,
"bb": 2
},
"b": "blue"
},
"d": [],
"e": [[], []],
"f": {}
}
This has 15 JSON entities:
5 of them are arrays or objects with children.
4 of them are empty arrays or objects.
6 of them are scalars.
Depending on what you're trying to do, you might consider only scalars to be "leaf nodes", or you might consider both scalars and empty arrays and objects to be leaf nodes.
Here's a filter that counts scalars:
[..|scalars]|length
Output:
6
And here's a filter that counts all entities which have no children. It just checks for all the scalar types explicitly (there are only six possible types for a JSON value) and if it's not one of those it must be an array or object, where we can check how many children it has with length.
[
..|
select(
(type|IN("boolean","number","string","null")) or
length==0
)
]|
length
Output:
10
Given an array of JSON objects, I'd like to output a CSV where one of the rows contains each object key and the others are based on each object value.
The input json is:
{
"PCID000": {
"OSmodle": "LINUX",
"IEversion": "2.15.0",
"hardwareUSB": [
"Card reader",
"keyboard"
],
"OrderStatus": "01"
},
"PCID999": {
"OSmodle": "LINUX",
"OSversion": "4.0",
"hardwareUSB": [],
"OrderStatus": "01"
}
}
The output would look something like this. The header can be hardcoded.
PCID,OSmodle,OSversion,IEversion,hardwareUSB, OrderStatus
"PCID000","LINUX",,"2.15.0","Card reader&keyboard","01"
"PCID999","LINUX","4.0",,"01
You can use the to_entries function to convert an object such as {"a": 1, "b": 2} to an array of key-value objects such as [{"key": "a", "value": 1}, {"key": "b", "value": 2}]. Then map over this to pick the key and the parts of the value of interest.
The jq script would look like this:
to_entries | map([
.key,
.value.OSmodle,
.value.OSversion,
.value.IEversion,
(.value.hardwareUSB | join("&")),
.value.OrderStatus])
| ["PCID", "OSmodle", "OSversion", "IEversion", "hardwareUSB", "OrderStatus"], .[]
| #csv
Output (with -r):
"PCID","OSmodle","OSversion","IEversion","hardwareUSB","OrderStatus"
"PCID000","LINUX",,"2.15.0","Card reader&keyboard","01"
"PCID999","LINUX","4.0",,"","01"
jqplay
I have json as a string "Str"
"{
"A": {
"id": 4
},
"B": {//Something},
"C": {
"A": {
"id": 2
}
},
"E": {
"A": null
},
"F": {//Something}
}"
I wanted all non null values of "A" which can be repeated anywhere in json. I wanted output like all contents of "A"
{"id": 4}
{"id": 2}
Can you please help me with Linux command to get this ?
Instead of line oriented ones use a tool which is capable of parsing JSON values syntax wise. An example using jq:
$ json_value='{"A":{"id":4},"B":{"foo":0},"C":{"A":{"id":2}},"E":{"A":null},"F":{"foo":0}}'
$
$ jq -c '..|objects|.A//empty' <<< "$json_value"
{"id":4}
{"id":2}
.. # list nodes recursively
| objects # select objects
| .A // empty # print A's value if present.
Let's say we have 2 json arrays. How to merge them into a single array with circe? Example:
Array 1:
[{"id": 1}, {"id": 2}, {"id": 3}]
Array 2:
[{"id": 4}, {"id": 5}, {"id": 6}]
Needed:
[{"id": 1}, {"id": 2}, {"id": 3}, {"id": 4}, {"id": 5}, {"id": 6}]
I've tried deepMerge, but it only keeps the contents of the argument, not of the calling object.
Suppose we've got the following set-up (I'm using circe-literal for convenience, but your Json values could come from anywhere):
import io.circe.Json, io.circe.literal._
val a1: Json = json"""[{"id": 1}, {"id": 2}, {"id": 3}]"""
val a2: Json = json"""[{"id": 4}, {"id": 5}, {"id": 6}]"""
Now we can combine them like this:
for { a1s <- a1.asArray; a2s <- a2.asArray } yield Json.fromValues(a1s ++ a2s)
Or:
import cats.std.option._, cats.syntax.cartesian._
(a1.asArray |#| a2.asArray).map(_ ++ _).map(Json.fromValues)
Both of these approaches are going to give you an Option[Json] that will be None if either a1 or a2 don't represent JSON arrays. It's up to you to decide what you want to happen in that situation .getOrElse(a2) or .getOrElse(a1.deepMerge(a2)) might be reasonable choices, for example.
As a side note, the current contract of deepMerge says the following:
Null, Array, Boolean, String and Number are treated as values, and values from the argument JSON completely replace values from this JSON.
This isn't set in stone, though, and it might not be unreasonable to have deepMerge concatenate JSON arrays—if you want to open an issue we can do some more thinking about it.