Is there a Julia package allowing to access json objects like jqlang?

General Usage
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1

In REPL it’s convenient to use jqlang syntax like

curl 'https://<graphql-api>' -X POST \
  -H 'content-type: application/json' \
  --data """<graphql-query>""" | \
jq '.data.blocks[0].number

is there a way to do something similar in Julia?

It’s already very convenient to do something like:

using JSON3, Pipe
@pipe read("data.json") |> JSON3.read |>
  getindex(_, :data) |> getindex(_, :blocks) |> getindex(_, 1)

but I am looking for a more compact way to explore the json object, it’s a bit cumbersome to call getindex multiple times.

2

Not sure if it solves your problem, but you can call getindex implicitly via indexing, e.g. (following your example):

@pipe read("data.json") |> JSON3.read |> _[:data] |> _[:blocks] |> _[1]

or even:

@pipe "data.json" |> read |> JSON3.read |> _[:data][:blocks][1]

Also check out this presentation at JuliaCon 2023.

1 Like
3

You can try using PropertyDicts to simplify field access via properties:

julia> using JSON, PropertyDicts
julia> content = JSON.parsefile("/path/to/my.json"; dicttype = PropertyDict);
julia> content.data.blocks[1].number
2 Likes
4

If you like jq you can use it directly from jq_jll.jl:

julia> using JSON3, jq_jll

julia> jq(data, expr) = sprint(io -> run(pipeline(IOBuffer(data), `$(jq_jll.jq()) -c $expr`, io)))
jq (generic function with 1 method)

julia> jq("""{"x": [{"y": 1},{"y": 2}]}""", "[.x[].y]") |> JSON3.read
2-element JSON3.Array{Int64, Base.CodeUnits{UInt8, String}, Vector{UInt64}}:
 1
 2
3 Likes
5

I’ve been using JSON3 a lot without knowing the motivations behind it, thanks for the share :wink:

6

Im curious, what is the benefit of using the jll compared to shelling out to regular jq?

You are running it in a subprocess anyway no? Is it simply the ability to install independently from the system binaries?

7

It means you don’t need to rely on jq being installed already. And you can control which version you use, just like any other package.

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