bettio
ExJSONPath - an Elixir JSONPath library
I am pleased to announce an initial release ExJSONPath.
ExJsonPath is an Elixir library which allows to query maps (JSON objects) and lists (JSON arrays), using JSONPath expressions.
We decided to implement ExJSONPath while working on Astarte Flow, since we wanted to allow users to query arbitrary JSON objects from their pipelines code.
ExJsonPath allows to query deserialized JSON files [1] using expressions similar to the following:
ExJsonPath.eval(store, "$.store.book[?(@.price > 20)].title")
{:ok, ["The Lord of the Rings"]}
ExJsonPath is not tied to JSON at all, the same kind of JSONPath expression can be used on any Elixir map or list.
Right now, the only hard requirement is that keys must be strings.
Hope you’ll find this useful ![]()
Let me know if you have any request/question/feedback.
[1]:
{ "store": {
"book": [
{ "category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{ "category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
}
}
Most Liked Responses
LostKobrakai
Looks interesting. I took a quick look at the code and it seems you’re recursing the structure manually. I’m wondering if it would make sense to convert to an Access pattern instead, so it could be used with get_in, put_in, … all by implementing one transformation from the JSONPath format to a list of Access accessors.
bettio
I know there are several software around that use it (e.g. kubectl).
The syntax is quite well known and there are tutorials, several tools (that allows users to test their expressions) and libraries in several languages.
So it was my first choice since it doesn’t require people to learn a new syntax.
I think you should focus your library to a specific use-case, my use-case was to allow people to write JSON templates and pipelines for arbitrary JSON inputs. As a side effect several kind of maps and lists are now supported by my JSONPath library.
I think I will add support to protocols and funs so I can extend my library to use-cases outside JSON.








