Demonstration settings and getting JSON values within an array using JSONPath syntax with NReJSON.

JSONPathExample.cs

// Make sure that the version of the RedisJson module that you're
// using is equal to or greater than version 20007. I'm using the
// following: redis/redis-stack-server:latest

using System.Text.Json;
using NReJSON;
using StackExchange.Redis;

// Let's define an example model instance to persist to Redis...
var example = new TestModel
{
    Things = new []
    {
        new NestedModel { Id = 1, Value = "The First Value."},
        new NestedModel { Id = 2, Value = "The Second Value."},
        new NestedModel { Id = 3, Value = "The Third Value."},
    }
};

// One time configuration of the JSON serializer for NReJSON to use.
NReJSONSerializer.SerializerProxy = new SystemTextJsonSerializerProxy();

var muxr = ConnectionMultiplexer.Connect("localhost");
var db = muxr.GetDatabase();

// Since I setup a JSON serializer the generic overload for the `JsonSetAsync` 
// method is used and our example model instance is automatically serialized
// to JSON for us.
await db.JsonSetAsync("TestObject", example);

// Get and write out the `Value` property for the object in the "Things" collection
// that has an `Id` value of 2.
var initialValue = await db.JsonGetAsync<string>("TestObject", "$.Things[?(@.Id==2)].Value");

Console.WriteLine(initialValue);

// Using a JSONPath expression I'm targeting the `Value` property of the item in the "Things"
// collection and setting it to the string value "2nd value". Notice that I've had to add
// some double quotes here. Since there are two overloads for `JsonSetAsync` one that accepts a 
// serialized JSON string and another that is generic and is intended to be used with an arbitrary
// type.
await db.JsonSetAsync("TestObject", "\"2nd value\"", "$.Things[?(@.Id==2)].Value");

// If you didn't want to quote the string, you could always cast the string value as an object
// and the serializer that was defined will be used to serialize the value.
// await db.JsonSetAsync("TestObject", (object)"2nd value", "$.Things[?(@.Id==2)].Value");

// Now we're going to re-get the target value by once again using the JSONPath that we used with the 
// previous two commands. 
var updatedValue = await db.JsonGetAsync<string>("TestObject", "$.Things[?(@.Id==2)].Value");

Console.WriteLine(updatedValue);


// Basic serializer proxy for System.Text.Json.
public class SystemTextJsonSerializerProxy : ISerializerProxy
{
    public TResult? Deserialize<TResult>(RedisResult serializedValue) =>
        serializedValue.IsNull ? default : JsonSerializer.Deserialize<TResult>(serializedValue.ToString() ?? "{}");

    public string Serialize<TObjectType>(TObjectType obj) =>
        JsonSerializer.Serialize(obj);
}

// The following are some example classes.
public class TestModel
{
    public NestedModel[] Things { get; set; }
}

public class NestedModel
{
    public int Id { get; set; }
    
    public string Value { get; set; }
}