Read a JSON file

The fs.open function is used to open a file and return a std.fs.File instance, in

The json.from_reader function is used to parse a JSON string from a reader and return a T instance base on the T type parameter.

INFO

The std.fs.File is has implemented the std.io.Read interface, so you can use it for json.from_reader function.

Navi Code

use std.json;
use std.fs.File;

struct User {
    name: string,
    id: int,
    profile: Profile?
}

struct Profile {
    city: string?
}

fn main() throws {
    let file = try File.open("path/to/user.json");
    let user = try json.parse::<User>(file);
}

If we have a user.json:

{
  "name": "Alice",
  "id": 42,
  "profile": { "city": "New York" }
}