Introducing RFC 9535 Go JSONPath and Playground

I've written and release a [RFC 9535 JSONPath][RFC] JSONPath Go package,
[github.com/theory/jsonpath]. Why? For a personal project, I needed a simpler
JSONPath engine to complement to the [Go SQL/JSON Path] package, and quickly
found myself implementing most of the [RFC]. So I decided do the whole thing.

Yes, yet another JSONPath package in Go. I really appreciate the idea of a
standard --- plus its support for features not included in the [original
design] from 2007, [such as object slices][slices]! But I could find no
reference to the RFC on pkg.go.dev. Today [the search] shows one!

Example
-------

Usage is straightforward; here's a quick example ([Go playground]):

``` go
package main

import (
"fmt"
"log"

"github.com/theory/jsonpath"
)

func main() {
// Parse a jsonpath query.
p, err := jsonpath.Parse(`$["name", "slogan"]`)
if err != nil {
log.Fatal(err)
}

// Select values from unmarshaled JSON input.
json := map[string]any{
"name": "Kamala Harris",
"title": "Vice President of the United States",
"home": "California",
"slogan": "We are not going back!",
}
items := p.Select(json)

// Show the result.
fmt.Printf("%#v\n", items)
}
```

And the output:

```go
[]interface {}{"Kamala Harris", "We are not going back!"}
```

🛝 Playground
-------------

No need to write code to try it out, though. I've also written a [playground
webapp] to encourage experimentation and exploration of the syntax and
behavior of the package. The implementation follows the precedents set by the
[Go SQL/JSON Playground] and design of the [Rust JSONPath Playground].
Moreover, thanks to [TinyGo], the [Wasm] file comes in at a mere 254K!

The webapp loads sample JSON from the [RFC], and randomly rotates through a
few example JSONPath queries. Fill in your own and tap the "Permalink" button
to share links. The Playground is a *stateless* JavaScript/Wasm web
application: data persists only in permalink URLs.[^github]

**🛝 Try this [example Playground permalink][slices] right now!**

Status
------

The root `jsonpath` package is stable and ready for use. Other packages remain
in flux, as I refactor and rejigger things in the coming weeks as part of the
aforementioned personal project. But for actual JSONPath execution and
querying, it should continue to work as-is for the foreseeable future.

I hope you find it useful.

[^github]: And whatever data [GitHub Pages collect] 😔.

[RFC]: https://www.rfc-editor.org/rfc/rfc9535.html
"RFC 9535 JSONPath: Query Expressions for JSON"
[github.com/theory/jsonpath]: https://pkg.go.dev/github.com/theory/jsonpath
[Go SQL/JSON Path]: https://justatheory.com/2024/07/go-sqljson-path/
"Introducing Go SQL/JSON Path and Playground"
[original design]: https://goessner.net/articles/JsonPath/
"Stefan Gössner: JSONPath - XPath for JSON"
[slices]: https://theory.github.io/jsonpath/?p=%2524.store.book%255B%253F%2540.author%2520%253D%253D%2520%27Herman%2520Melville%27%255D%255B%27title%27%252C%2520%27author%27%252C%2520%27price%27%255D&j=%257B%250A%2520%2520%2522store%2522%253A%2520%257B%250A%2520%2520%2520%2520%2522book%2522%253A%2520%255B%250A%2520%2520%2520%2520%2520%2520%257B%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522category%2522%253A%2520%2522reference%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522author%2522%253A%2520%2522Nigel%2520Rees%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522title%2522%253A%2520%2522Sayings%2520of%2520the%2520Century%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522price%2522%253A%25208.95%250A%2520%2520%2520%2520%2520%2520%257D%252C%250A%2520%2520%2520%2520%2520%2520%257B%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522category%2522%253A%2520%2522fiction%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522author%2522%253A%2520%2522Evelyn%2520Waugh%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522title%2522%253A%2520%2522Sword%2520of%2520Honour%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522price%2522%253A%252012.99%250A%2520%2520%2520%2520%2520%2520%257D%252C%250A%2520%2520%2520%2520%2520%2520%257B%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522category%2522%253A%2520%2522fiction%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522author%2522%253A%2520%2522Herman%2520Melville%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522title%2522%253A%2520%2522Moby%2520Dick%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522isbn%2522%253A%2520%25220-553-21311-3%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522price%2522%253A%25208.99%250A%2520%2520%2520%2520%2520%2520%257D%252C%250A%2520%2520%2520%2520%2520%2520%257B%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522category%2522%253A%2520%2522fiction%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522author%2522%253A%2520%2522J.%2520R.%2520R.%2520Tolkien%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522title%2522%253A%2520%2522The%2520Lord%2520of%2520the%2520Rings%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522isbn%2522%253A%2520%25220-395-19395-8%2522%252C%250A%2520%2520%2520%2520%2520%2520%2520%2520%2522price%2522%253A%252022.99%250A%2520%2520%2520%2520%2520%2520%257D%250A%2520%2520%2520%2520%255D%252C%250A%2520%2520%2520%2520%2522bicycle%2522%253A%2520%257B%250A%2520%2520%2520%2520%2520%2520%2522color%2522%253A%2520%2522red%2522%252C%250A%2520%2520%2520%2520%2520%2520%2522price%2522%253A%2520399%250A%2520%2520%2520%2520%257D%250A%2520%2520%257D%250A%257D&o=1
[the search]: https://pkg.go.dev/search?q=RFC+9535 "pkg.go.dev search: RFC 9535"
[Go playground]: https://go.dev/play/p/wmJvZdOl28D
[playground webapp]: https://theory.github.io/jsonpath/ "Go JSONPath Playground"
[TinyGo]: https://tinygo.org/ "TinyGo - A Go Compiler For Small Places"
[Wasm]: https://webassembly.org/ "WebAssembly"
[Go SQL/JSON Playground]: https://theory.github.io/sqljson/
[Rust JSONPath Playground]: https://serdejsonpath.lives

-------------------------------------------------------------------------------

❖ Monday, 4 Nov 2024
By David E. Wheeler
https://justatheory.com/2024/11/go-jsonpath-playground/

More about...

* Go: https://justatheory.com/tags/go/
* JSONPath: https://justatheory.com/tags/jsonpath/
* Playground: https://justatheory.com/tags/playground/
* RFC 9535: https://justatheory.com/tags/rfc-9535/