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Programming-Idioms

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  • Go

Idiom #91 Load JSON file into object

Read from the file data.json and write its content into the object x.
Assume the JSON data is suitable for the type of x. 

import "encoding/json"
import "os"
buffer, err := os.ReadFile("data.json")
if err != nil {
	return err
}
err = json.Unmarshal(buffer, &x)
if err != nil {
	return err
}

buffer is a []byte.
&x is the address of x.
You must check errors after each step.
import "encoding/json"
r, err := os.Open(filename)
if err != nil {
	return err
}
decoder := json.NewDecoder(r)
err = decoder.Decode(&x)
if err != nil {
	return err
}

Create and use a *json.Decoder
(require '[clojure.java.io :refer [file]])
(require '[jsonista.core :refer [read-value]])
(def x (read-value (file "data.json")))
New implementation...
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buffer, err := os.ReadFile("data.json")
if err != nil {
	return err
}
err = json.Unmarshal(buffer, &x)
if err != nil {
	return err
}
r, err := os.Open(filename)
if err != nil {
	return err
}
decoder := json.NewDecoder(r)
err = decoder.Decode(&x)
if err != nil {
	return err
}
(def x (read-value (file "data.json")))
JObject x = JObject.Parse(File.ReadAllText("data.json"));

JSONValue x = "data.json".readText.parseJSON;

struct User {
    int age;
    string name;

    this(JSONValue user) {
        age  = user["age"];
        name = user["name"];
    }
}

auto user = User(x);
Map x = json.jsonDecode(await new File('data.json').readAsString());
Map x = json.jsonDecode(new File('data.json').readAsStringSync());
defmodule JsonTest do
  def get_json(filename) do
    with {:ok, body} <- File.read(filename),
         {:ok, json} <- Poison.decode(body), do: {:ok, json}
  end
end

x = JsonTest.get_json("data.json")
const x = JSON.parse(fs.readFileSync('./data.json'));
const x = require('./data.json');
file = io.open("data.json")
x = cjson.decode(file:read("a"))
file:close()

$x = json_decode(file_get_contents('data.json'));
my $str = read_file('data.json');
my $x = decode_json($str);
with open("data.json", "r") as input:
    x = json.load(input)
x = JSON.parse(File.read('data.json'))
let x = ::serde_json::from_reader(File::open("data.json")?)?;