I'm very new to jq and this post is a result of not understanding the mechanics behind jq.
I could develop a bash script, which does what I want but jq and it's JSON super-powers have intrigued me and I'd like to learn it by applying to real world scenarios. Here's one...
BTW, I've tried to make use of the existing jq related SO solutions for merging/joining JSONs but have failed.
The closest I came to what I needed was to use an INDEX and a concatenation of $x + . , however I was only getting the LAST item from my second (c2) json.
So, my problem is as follows:
There are Two JSON files:
JSON #1 will have unique "id" and "type" keys - among other key/value pairs, which I've removed for better clarity of my post.
JSON #2 will contain multiples/non-unique "type" keys, which I'd like to match these two JSON files on. This JSON #2 will also contain other key/value pairs, which are expected to be contained in the resultant output.
My output requirements are:
I'd like to obtain a (one per line or a single array) list of all combinations of matching key/values pairs between c1 and c2 array where the value of the "type" key (string) matches between c1 and c2 exactly.
One more question, how much more difficult would it be to scale the solution to perform similar matching/joining between three JSON files at once - again on the same value of a particular key?
Any assistance or even just hints on how to solve and understand how to solve this would be greatly appreciated!
1st input file: JSON #1, Array c1 (collection 1)
{ "c1":
[
{ "c1id":1, "type":"alpha" },
{ "c1id":2, "type":"beta" }
]
}
2nd input file: JSON #2, Array c2 (collection 2)
{
"c2":
[
{ "c2id":1,"type":"alpha","serial":"DDBB001"} ,
{ "c2id":2,"type":"beta","serial":"DDBB007"} ,
{ "c2id":3,"type":"alpha","serial":"DDTT005"} ,
{ "c2id":4,"type":"beta","serial":"DDAA002"} ,
{ "c2id":5,"type":"yotta","serial":"DDCC017"}
]
}
Expected output:
{"c1id":1,"type":"alpha","c2id":1,"serial":"DDBB001"}
{"c1id":1,"type":"alpha","c2id":3,"serial":"DDTT005"}
{"c1id":2,"type":"beta","c2id":2,"serial":"DDBB007"}
{"c1id":2,"type":"beta","c2id":4,"serial":"DDAA002"}
You will notice that type "yotta" from the c2 is not included in the output. This is expected. Only "types" which exist in c1 and match c2 are expected to be in the results. I guess this is implied by this being a matching/joining exercise - I added it just for clarity - I hope it worked.
Here's an example of using INDEX and JOIN:
jq --compact-output --slurpfile c1 c1.json '
INDEX(
$c1[0].c1[];
.type
) as $index |
JOIN(
$index;
.c2[];
.type;
reverse|add
)
' c2.json
The first argument to INDEX needs to produce a stream of items, which is why we apply [] to get the items from the array individually. The second argument selects our index key.
We use the four argument version of JOIN. The first argument is the index itself, the second is a stream of objects to be joined to the index, the third argument selects the lookup key from the streamed objects, and the fourth argument is an expression to assemble the join object. The input to that expression is a stream of two-item arrays, each looking something like this:
[{"c2id":1,"type":"alpha","serial":"DDBB001"},{"c1id":1,"type":"alpha"}]
Since we just want to combine all the keys and values from the objects we just use add, but we first reverse the array to nicely arrange the c1 fields before the c2 fields. The end result is as you hoped:
{"c1id":1,"type":"alpha","c2id":1,"serial":"DDBB001"}
{"c1id":2,"type":"beta","c2id":2,"serial":"DDBB007"}
{"c1id":1,"type":"alpha","c2id":3,"serial":"DDTT005"}
{"c1id":2,"type":"beta","c2id":4,"serial":"DDAA002"}
Related
Original Data
I have the following JSON:
{
"foo":[
"asd",
"fgh"
],
"bar":[
"abc",
"xyz",
"ert"
],
"baz":[
"something"
]
}
Now I want to transform it to a "flat" CSV, such that for every key in my object the list in the value is expanded to n rows with n being the number of entries in the respective list.
Expected Output
foo;asd
foo;fgh
bar;abc
bar;xyz
bar;ert
baz;something
Approaches
I guess I need to use to_entries and then for each .value repeat the same .key for the first column. The jq docs state that:
Thus as functions as something of a foreach loop.
So I tried combining
to_entriesto give the keys and values from my dictionary an accessible name
then build kind of a foreach loop around the .values
and pass the result to #csv
to_entries|map(.value) as $v|what goes here?|#csv
I prepared something that at least compiles here
Don't need to use _entries function, a simple key/value lookup and string interpolation should suffice
keys_unsorted[] as $k | "\($k);\( .[$k][])"
The construct .[$k][] is an expression that first expands the value associated with each key, i.e. .foo and then with object construction, produces multiple results for each key identified and stored in $k variable.
If you want to stringify column A,B,C for a few rows it makes sense that JSON.stringify returns something like [ ["1a","2a","3a"], ["1b","2b", "3b"] ].
However if you are using just one column i.e. a 1 dimensional array, then what JSON.stringify does is terrible: [ ["1a"], ["1b"] ]
What my API expects is ["1a","1b"]
What I am missing?: How can I tell it to properly format it?
From the question
However if you are using just one column i.e. a 1 dimensional array, then what JSON.stringify does is terrible: [ ["1a"], ["1b"] ]
It looks that you have a misconception, as getValues() returns a bi-dimensional no matter if the range refers to a single row or a single column. Anyway, one way to convert the bi-dimentional array into a one-dimension array is by using Array.prototype.flat().
let column = [[1],[2],[3]]
console.log(column.flat())
I'm starting to explore the JSON1 library for sqlite and have been so far successful in the basic queries I've created. I'm now looking to create a more complicated query that pulls data from multiple levels.
Here's the example JSON object I'm starting with (and most of the data is very similar).
{
"height": 140.0,
"id": "cp",
"label": {
"bind": "cp_label"
},
"type": "color_picker",
"user_data": {
"my_property": 2
},
"uuid": "948cb959-74df-4af8-9e9c-c3cb53ac9915",
"value": {
"bind": "cp_color"
},
"width": 200.0
}
This json object is buried about seven levels deep in a json structure and I pulled it from the larger json construct using an sql statement like this:
SELECT value FROM forms, json_tree(forms.formJSON, '$.root')
WHERE type = 'object'
AND json_extract(value, '$.id') = #sControlID
// In this example, #sControlID is a variable that represents the `id` value we're looking for, which is 'cp'
But what I really need to pull from this object are the following:
the value from key type ("color_picker" in this example)
the values from keys bind ("cp_color" and "cp_label" in this example)
the keys value and label (which have values of {"bind":"<string>"} in this example)
For that last item, the key name (value and label in this case) can be any number of keywords, but no matter the keyword, the value will be an object of the form {"bind":"<some_string>"}. Also, there could be multiple keys that have a bind object associated with them, and I'd need to return all of them.
For the first two items, the keywords will always be type and bind.
With the json example above, I'd ideally like to retrieve two rows:
type key value
color_picker value cp_color
color_picker label cp_label
When I use json_extract methods, I end up retrieving the object {"bind":"cp_color"} from the json_tree table, but I also need to retrieve the data from the parent object. I feel like I need to do some kind of union, but my attempts have so far been unsuccessful. Any ideas here?
Note: if the {"bind":"<string>"} object doesn't exist as a child of the parent object, I don't want any rows returned.
Well, I was on the right track and eventually figured out it. I created a separate query for each of the items I was looking for, then INNER JOINed all the json_tree tables from each of the queries to have all the required fields available. Then I json_extracted the required data from each of the json fields I needed data from. In the end, it gave me exactly what I was looking for, though I'm sure it could be written more efficiently.
For anyone interested, this is what hte final query ended up looking like:
SELECT IFNULL(json_extract(parent.value, '$.type'), '_window_'), child.key, json_extract(child.value, '$.bind') FROM (SELECT json_tree.* FROM nui_forms, json_tree(nui_forms.formJSON, '$') WHERE type = 'object' AND json_extract(nui_forms.formJSON, '$.id') = #sWindowID) parent INNER JOIN (SELECT json_tree.* FROM nui_forms, json_tree(nui_forms.formJSON, '$') WHERE type = 'object' AND json_extract(value, '$.bind') != 'NULL' AND json_extract(nui_forms.formJSON, '$.id') = #sWindowID) child ON child.parent = parent.id;
If you have any tips on reducing its complexity, feel free to comment!
I have a huge json file of about 4500 lines.
I wish to extract the value of all the keys named "value".
The levels of json paths are not same.
JSON Sample :
{
k1:v1,
k2:v2,
k3:v3,
k4:{
k5:v5,
k6:{
k7:v7,
value:"value1"
}
}
k8:v8,
value:"value2"
}
There are multiple such "value" tags.
Is there a way using jq to get all the values ?
Use recursive descent.
.. | objects | if has("value") then .value else empty end
Here is a slightly shorter variation of oguz ismail's answer which uses Optional Object Identifier .foo? and Alternative operator // along with recursive descent.
.. | .value? // empty
Example output (using corrected JSON Sample)
"value2"
"value1"
Note that this shortcut won't produce the same output if the "value" key may be null as // can't distinguish between a null "value" and a null produced by the ? operator when the "value" key is missing. It that's a concern then testing for the presence of the "value" key with has is better.
Try it online!
I am trying to extract data from some JSON with JQ - I have already got it down to the last level of data that I need to extract from, but I am completely stumped as to how to proceed with how this part of the data is formatted.
An example would be:
{
"values": [
[
1483633677,
42
]
],
"columns": [
"time",
"count_value"
],
"name": "response_time_error"
}
I would want to extract just the value for a certain column (e.g. count_value) and I can extract it by using [-1] in this specific case, but I want to select the column by its name in case they change in the future.
If you're only extracting a single value and the arrays will always correspond with eachother, you could find the index in the columns array then use that index into the values array.
It seems like values is an array of rows with those values. Assuming you want to output the values of all rows with the selected column:
$ jq --arg col 'count_value' '.values[][.columns | index($col)]' input.json
If the specified column name does not exist in .columns, then Jeff's filter will fail with a rather obscure error message. It might therefore be preferable to check whether the column name is found. Here is an illustration of how to do so:
jq --arg col count_value '
(.columns | index($col)) as $ix
| if $ix then .values[][$ix] else empty end' input.json
If you want an informative error message to be printed, then replace empty with something like:
error("specified column name, \($col), not found")