Edit a json Entry

[graceful knot]

<@&987246399047479336> please have a look, thanks.

[graceful knot]

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[rustic badger]

just wait for him, he will probably help you with that

but I think its quite early in the morning for him rn

[nimble sentinel]

import dev.mccue.json.Json;
import dev.mccue.json.JsonDecoder;

public class Main {
    public static void main(String[] args) {
        var j = Json.readString("{ \"name\"   : \"John Smith\", \"other\": 123} ");

        var j2 = Json.objectBuilder(JsonDecoder.object(j))
                .put("name", "John Doe")
                .build();

        System.out.println(j);
        System.out.println(j2);
    }
}

i think there is room for a better api probably

but copy it into a builder, replace properties

if you need to do something more involved then

import dev.mccue.json.Json;
import dev.mccue.json.JsonDecoder;

import java.util.HashMap;

public class Main {
    public static void main(String[] args) {
        var j = Json.readString("{ \"name\"   : \"John Smith\", \"other\": 123} ");

        var modified = new HashMap<>(JsonDecoder.object(j));
        modified.put("name", Json.of("Joe Doe"));
        if (modified.containsKey("other")) {
            modified.put("apple", Json.of("what"));
        }

        var j2 = Json.of(modified);

        System.out.println(j);
        System.out.println(j2);
    }
}

you can go through normal collections

the JsonDecoder.object is just the same ol' "cast to JsonObject or throw"

API suggestions welcome - clearly some things that are easy in python are still hard here

j = json.loads(...)
j["a"]["b"] = 123

Another approach could be to round trip through an object

import dev.mccue.json.Json;
import dev.mccue.json.JsonDecoder;
import dev.mccue.json.JsonObject;

class Blob {
    String name;
    JsonObject other;
    
    static Blob fromJson(Json json) {
        var blob = new Blob();
        blob.name = JsonDecoder.field(json, "name", JsonDecoder::string);
        blob.other = JsonDecoder.object(json);
        return blob;
    }
    
    Json toJson() {
        return Json.objectBuilder(other)
                .put("name", name)
                .build();
    }
}

public class Main {
    public static void main(String[] args) {
        var j = Json.readString("{ \"name\"   : \"John Smith\", \"other\": 123} ");

        var blob = Blob.fromJson(j);
        blob.name = "Johnny Quest";
        
        var j2 = blob.toJson();

        System.out.println(j);
        System.out.println(j2);
    }
}

Depends what you want to do

do you want to just deal with that one k/v

or do you want to update one part of a larger document

can you give a more concrete example?

so its a big list like

[
  { "name"   : "One Smith"},
  { "name"   : "Two Smith"},
  { "name"   : "Red Smith"},
  { "name"   : "Blue Smith"}
]

how many keys are there

is the set known or not known

like is each thing a certain "shape"

like

name, age, height

okay

then honestly, reading into an object is the least annoying

read the json to some record or whatever, do your logic, then write it all back out

yeah there isn't a different way to work with a big json file

import dev.mccue.json.Json;
import dev.mccue.json.JsonDecoder;
import dev.mccue.json.JsonEncodable;
import dev.mccue.json.JsonObject;

import java.util.List;

record Person(String name, int age) implements JsonEncodable {
    public static Person fromJson(Json json) {
        return new Person(
                JsonDecoder.field(json, "name", JsonDecoder::string),
                JsonDecoder.field(json, "age", JsonDecoder::int_)
        );
    }

    @Override
    public Json toJson() {
        return Json.objectBuilder()
                .put("name", name)
                .put("age", age)
                .build();
    }

    Person withName(String name) {
        return new Person(name, this.age);
    }
}

public class Main {
    public static void main(String[] args) {
        var j = Json.readString("""
                [
                  { "name"   : "One Smith", "age": 20 },
                  { "name"   : "Two Smith", "age": 30 },
                  { "name"   : "Red Smith", "age": 25 },
                  { "name"   : "Blue Smith", "age": 40 }
                ]
                """);

        List<Person> people = JsonDecoder.array(j, Person::fromJson);
        
        List<Person> newPeople = people.stream()
                .map(person -> {
                    if (person.name().equals("Two Smith")) {
                        return person.withName("bob");
                    }
                    else {
                        return person;
                    }
                })
                .toList();
        
        Json j2 = Json.of(newPeople);

        System.out.println(j);
        System.out.println(j2);
    }
}

i'll add some examples to the readme

since im working on it anyways