Are nested objects supported in a lens selector?

[zkxs]

Hi, I may be missing something obvious, but I can't figure out if the lens selector can filter against nested objects or not.

Here's an example input json:

[
    {
        "metadata": {
            "unique_id": "fizzbuzz"
        },
        "data": ["foo", "bar", "baz"]
    },
    {
        "metadata": {
            "unique_id": "giant"
        },
        "data": ["fee", "fi", "fo", "fum"]
    }
]

What I'd like to do is get the data array for all objects with a specific unique_id.

So if I'm looking for "unique_id"="fizzbuzz", then I'd expect the following output:

[
  [
    "foo",
    "bar",
    "baz"
  ]
]

Intuitively, I thought the lens selector would be able to do something like this, but in practice it gives a parse error:

jql '|={"metadata""unique_id"="fizzbuzz"}' example.json # Unable to parse input

The only thing I was able to figure out was a workaround with flattening. While this does give the desired output, flattening is destructive and I'd rather avoid it if possible.

jql '|> .. <| |={"metadata.unique_id"="fizzbuzz"} |> "data" <|' example.json # desired output

[yamafaktory]

Hi @zkxs,

Thanks for your feedback!

Indeed this is not possible in the current state of jql since a Lens is basically a tuple of key (str) + LensValue (a JSON primitive):

jql/crates/jql-parser/src/tokens.rs

Line 75 in dbf8997

pub struct Lens<'a>(pub(crate) &'a str, pub(crate) Option<LensValue<'a>>);

jql/crates/jql-parser/src/tokens.rs

Lines 109 to 118 in dbf8997

	pub enum LensValue<'a> {
	/// Variant for a JSON boolean.
	Bool(bool),
	/// Variant for JSON null.
	Null,
	/// Variant for a JSON number.
	Number(usize),
	/// Variant for a JSON string.
	String(&'a str),
	}

To make it work, I'll need to refactor the parser implementation to allow a Lens to hold other selectors as key.

I'll think about it and see if that's not going to add too much complexity.

[yamafaktory]

@zkxs I've prepared a draft PR to allow a subset of selectors to work with lenses. I need to do some more testing (and update the documentation too) and then will make a new release.

[yamafaktory]

@zkxs I've just released a new major version which now supports lenses with selectors. Thanks a lot for bringing this issue to the table 👍🏼 .