We Keep Coding

System.Text.Json - failing to deserialize a REST response

I'm trying to implement the following API Endpoint. Due to the fact, System.Text.Json is now preferred over Newtonsoft.Json, I decided to try it. The response clearly works, but the deserialization doesn't.
Response
https://pastebin.com/VhDw5Rsg (Pastebin because it exceeds the limits)
Issue
I pasted the response into an online converter and it used to work for a bit, but then it broke again once I put the comments.
How do I fix it? I would also like to throw an exception if it fails to deserialize it.
Snippet
using System.Net;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using Ardalis.GuardClauses;
using RestSharp;
namespace QSGEngine.Web.Platforms.Binance;
/// <summary>
/// Binance REST API implementation.
/// </summary>
internal class BinanceRestApiClient : IDisposable
{
/// <summary>
/// The base point url.
/// </summary>
private const string BasePointUrl = "https://api.binance.com";
/// <summary>
/// The key header.
/// </summary>
private const string KeyHeader = "X-MBX-APIKEY";
/// <summary>
/// REST Client.
/// </summary>
private readonly IRestClient _restClient = new RestClient(BasePointUrl);
/// <summary>
/// Initializes a new instance of the <see cref="BinanceRestApiClient"/> class.
/// </summary>
/// <param name="apiKey">Binance API key.</param>
/// <param name="apiSecret">Binance Secret key.</param>
public BinanceRestApiClient(string apiKey, string apiSecret)
{
Guard.Against.NullOrWhiteSpace(apiKey, nameof(apiKey));
Guard.Against.NullOrWhiteSpace(apiSecret, nameof(apiSecret));
ApiKey = apiKey;
ApiSecret = apiSecret;
}
/// <summary>
/// The API key.
/// </summary>
public string ApiKey { get; }
/// <summary>
/// The secret key.
/// </summary>
public string ApiSecret { get; }
/// <summary>
/// Gets the total account cash balance for specified account type.
/// </summary>
/// <returns></returns>
/// <exception cref="Exception"></exception>
public AccountInformation? GetBalances()
{
var queryString = $"timestamp={GetNonce()}";
var endpoint = $"/api/v3/account?{queryString}&signature={AuthenticationToken(queryString)}";
var request = new RestRequest(endpoint, Method.GET);
request.AddHeader(KeyHeader, ApiKey);
var response = ExecuteRestRequest(request);
if (response.StatusCode != HttpStatusCode.OK)
{
throw new Exception($"{nameof(BinanceRestApiClient)}: request failed: [{(int)response.StatusCode}] {response.StatusDescription}, Content: {response.Content}, ErrorMessage: {response.ErrorMessage}");
}
var deserialize = JsonSerializer.Deserialize<AccountInformation>(response.Content);
return deserialize;
}
/// <summary>
/// If an IP address exceeds a certain number of requests per minute
/// HTTP 429 return code is used when breaking a request rate limit.
/// </summary>
/// <param name="request"></param>
/// <returns></returns>
private IRestResponse ExecuteRestRequest(IRestRequest request)
{
const int maxAttempts = 10;
var attempts = 0;
IRestResponse response;
do
{
// TODO: RateLimiter
//if (!_restRateLimiter.WaitToProceed(TimeSpan.Zero))
//{
// Log.Trace("Brokerage.OnMessage(): " + new BrokerageMessageEvent(BrokerageMessageType.Warning, "RateLimit",
// "The API request has been rate limited. To avoid this message, please reduce the frequency of API calls."));
// _restRateLimiter.WaitToProceed();
//}
response = _restClient.Execute(request);
// 429 status code: Too Many Requests
} while (++attempts < maxAttempts && (int)response.StatusCode == 429);
return response;
}
/// <summary>
/// Timestamp in milliseconds.
/// </summary>
/// <returns>The current timestamp in milliseconds.</returns>
private long GetNonce()
{
return DateTimeOffset.Now.ToUnixTimeMilliseconds();
}
/// <summary>
/// Creates a signature for signed endpoints.
/// </summary>
/// <param name="payload">The body of the request.</param>
/// <returns>A token representing the request params.</returns>
private string AuthenticationToken(string payload)
{
using var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(ApiSecret));
var computedHash = hmac.ComputeHash(Encoding.UTF8.GetBytes(payload));
return BitConverter.ToString(computedHash).Replace("-", "").ToLowerInvariant();
}
/// <summary>
/// The standard dispose destructor.
/// </summary>
~BinanceRestApiClient() => Dispose(false);
/// <summary>
/// Returns true if it is already disposed.
/// </summary>
public bool IsDisposed { get; private set; }
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
/// <param name="disposing">If this method is called by a user's code.</param>
private void Dispose(bool disposing)
{
if (IsDisposed) return;
if (disposing)
{
}
IsDisposed = true;
}
/// <summary>
/// Throw if disposed.
/// </summary>
/// <exception cref="ObjectDisposedException"></exception>
private void ThrowIfDisposed()
{
if (IsDisposed)
{
throw new ObjectDisposedException("BinanceRestClient has been disposed.");
}
}
}
namespace QSGEngine.Web.Platforms.Binance;
/// <summary>
/// Information about the account.
/// </summary>
public class AccountInformation
{
/// <summary>
/// Commission percentage to pay when making trades.
/// </summary>
public decimal MakerCommission { get; set; }
/// <summary>
/// Commission percentage to pay when taking trades.
/// </summary>
public decimal TakerCommission { get; set; }
/// <summary>
/// Commission percentage to buy when buying.
/// </summary>
public decimal BuyerCommission { get; set; }
/// <summary>
/// Commission percentage to buy when selling.
/// </summary>
public decimal SellerCommission { get; set; }
/// <summary>
/// Boolean indicating if this account can trade.
/// </summary>
public bool CanTrade { get; set; }
/// <summary>
/// Boolean indicating if this account can withdraw.
/// </summary>
public bool CanWithdraw { get; set; }
/// <summary>
/// Boolean indicating if this account can deposit.
/// </summary>
public bool CanDeposit { get; set; }
/// <summary>
/// The time of the update.
/// </summary>
//[JsonConverter(typeof(TimestampConverter))]
public long UpdateTime { get; set; }
/// <summary>
/// The type of the account.
/// </summary>
public string AccountType { get; set; }
/// <summary>
/// List of assets with their current balances.
/// </summary>
public IEnumerable<Balance> Balances { get; set; }
/// <summary>
/// Permission types.
/// </summary>
public IEnumerable<string> Permissions { get; set; }
}
/// <summary>
/// Information about an asset balance.
/// </summary>
public class Balance
{
/// <summary>
/// The asset this balance is for.
/// </summary>
public string Asset { get; set; }
/// <summary>
/// The amount that isn't locked in a trade.
/// </summary>
public decimal Free { get; set; }
/// <summary>
/// The amount that is currently locked in a trade.
/// </summary>
public decimal Locked { get; set; }
/// <summary>
/// The total balance of this asset (Free + Locked).
/// </summary>
public decimal Total => Free + Locked;
}

System.Text.Json is implemented quite different compared to Newtonsoft.Json. It is written to be first and foremost a very fast (de)serializer, and try to be allocation-free as much as possible.
However, it also comes with its own set of limitations, and one of those limitations is that out of the box it's a bit more rigid in what it supports.
Let's look at your JSON:
{"makerCommission":10,"takerCommission":10,"buyerCommission":0,
"sellerCommission":0,"canTrade":true,"canWithdraw":true,"canDeposit":true,
"updateTime":1636983729026,"accountType":"SPOT",
"balances":[{"asset":"BTC","free":"0.00000000","locked":"0.00000000"},
{"asset":"LTC","free":"0.00000000","locked":"0.00000000"},
(reformatted and cut for example purposes)
There's two issues here that needs to be resolved:
The properties in the JSON is written with a lowercase first letter. This will simply not match the properties in your .NET Types out of the box.
The values for free and locked are strings in the JSON but typed as decimal in your .NET types.
To fix these, your deserialization code needs to tell System.Text.Json how to deal with them, and this is how:
var options = new System.Text.Json.JsonSerializerOptions
{
PropertyNameCaseInsensitive = true,
NumberHandling = JsonNumberHandling.AllowReadingFromString
};
And then you pass this object in through the deserialization method, like this:
… = JsonSerializer.Deserialize<AccountInformation>(response.Content, options);
This should properly deserialize this content into your objects.

Error converting json retrieved from API to C# class using NewtonSoft

2 parts to this question.
I am the owner of an API and if there is no data to return (based on business rules) the response is delivered like so:
var resp = new { error = "", code = (int)HttpStatusCode.OK, data = leads};
var json = JsonConvert.SerializeObject(resp);
var response = Request.CreateResponse(HttpStatusCode.OK);
response.Content = new StringContent(json, System.Text.Encoding.UTF8, "application/json");
return Ok(json);
And when I call this in Postman, this is rendered as:
"{\"error\":\"\",\"code\":200,\"data\":[]}"
What is with the slashes?
My second part, which may or may not be fixed by fixing the slashes, is when I consume the API, and deserialize the response to an object, I receive the following error
Error converting value "{"error":"","code":200,"data":[]}" to type 'DataTypes.IntegrationResponse'. Path '', line 1, position 43.
For those who need it, IntegrationResponse is:
public class IntegrationResponse
{
public string error { get; set; }
public int code { get; set; }
public List<IntegrationLead> data { get; set; }
}

I'd make this a comment if I could, need more rep. That said -
Try making List<IntegrationLead> an InegrationLead[] and all the slashes are to escape the quotes and you have an awesome name. Cheers!

Here is how i will do this
in APi
public ActionResult SomeActionMethod() {
return Json(new {foo="bar", baz="Blech"});
}
If you want to use JsonConverter and control how the data get serilized then
public class JsonNetResult : ActionResult
{
/// <summary>
/// Initializes a new instance of the <see cref="JsonNetResult"/> class.
/// </summary>
public JsonNetResult()
{
}
/// <summary>
/// Gets or sets the content encoding.
/// </summary>
/// <value>The content encoding.</value>
public Encoding ContentEncoding { get; set; }
/// <summary>
/// Gets or sets the type of the content.
/// </summary>
/// <value>The type of the content.</value>
public string ContentType { get; set; }
/// <summary>
/// Gets or sets the data.
/// </summary>
/// <value>The data object.</value>
public object Data { get; set; }
/// <summary>
/// Enables processing of the result of an action method by a custom type that inherits from the <see cref="T:System.Web.Mvc.ActionResult"/> class.
/// </summary>
/// <param name="context">The context in which the result is executed. The context information includes the controller, HTTP content, request context, and route data.</param>
public override void ExecuteResult(ControllerContext context)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
HttpResponseBase response = context.HttpContext.Response;
response.ContentType = !String.IsNullOrWhiteSpace(this.ContentType) ? this.ContentType : "application/json";
if (this.ContentEncoding != null)
{
response.ContentEncoding = this.ContentEncoding;
}
if (this.Data != null)
{
response.Write(JsonConvert.SerializeObject(this.Data));
}
}
}
Blockquote
public class CallbackJsonResult : JsonNetResult
{
/// <summary>
/// Initializes a new instance of the <see cref="CallbackJsonResult"/> class.
/// </summary>
/// <param name="statusCode">The status code.</param>
public CallbackJsonResult(HttpStatusCode statusCode)
{
this.Initialize(statusCode, null, null);
}
/// <summary>
/// Initializes a new instance of the <see cref="CallbackJsonResult"/> class.
/// </summary>
/// <param name="statusCode">The status code.</param>
/// <param name="description">The description.</param>
public CallbackJsonResult(HttpStatusCode statusCode, string description)
{
this.Initialize(statusCode, description, null);
}
/// <summary>
/// Initializes a new instance of the <see cref="CallbackJsonResult"/> class.
/// </summary>
/// <param name="statusCode">The status code.</param>
/// <param name="data">The callback result data.</param>
public CallbackJsonResult(object data, HttpStatusCode statusCode = HttpStatusCode.OK)
{
this.ContentType = null;
this.Initialize(statusCode, null, data);
}
/// <summary>
/// Initializes a new instance of the <see cref="CallbackJsonResult"/> class.
/// </summary>
/// <param name="statusCode">The status code.</param>
/// <param name="description">The description.</param>
/// <param name="data">The callback result data.</param>
public CallbackJsonResult(HttpStatusCode statusCode, string description, object data)
{
this.Initialize(statusCode, description, data);
}
/// <summary>
/// Initializes this instance.
/// </summary>
/// <param name="statusCode">The status code.</param>
/// <param name="description">The description.</param>
/// <param name="data">The callback result data.</param>
private void Initialize(HttpStatusCode statusCode, string description, object data)
{
Data = new JsonData() { Success = statusCode == HttpStatusCode.OK, Status = (int)statusCode, Description = description, Data = data };
}
}
}
then create an extention
/// <summary>
/// return Json Action Result
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="o"></param>
/// <param name="JsonFormatting"></param>
/// <returns></returns>
public static CallbackJsonResult ViewResult<T>(this T o)
{
return new CallbackJsonResult(o);
}
No APi simple use the extention that you created
public ActionResult SomeActionMethod() {
return new { error = "", code = (int)HttpStatusCode.OK, data = leads}.ViewResult();
}

Synchronising a collection over a websocket connection

I'm working on a client-server system at the moment, and I'm trying to get a collection to synchronise across a websocket. Everything is in C# + .Net 4.5, and I was wondering if there was a particular best practise for synchronising data over a websocket. It's a one way sync:
Server: BindingCollection< MyClass > ----- Websocket -----> Client: BindingCollection< MyClass >
The collection could be up to 1000 objects with 20 fields each so sending the whole lot each time seems a little wasteful.

I would use a observer pattern and only send the changed object to be synced.
So I finally took the time to write a small example.
I am using a in-memory generic repository that invokes events on changes. The changes is then sent to all clients so that you do not have to send the complete list/collection.
A simple model to monitor
using System;
namespace SynchronizingCollection.Common.Model
{
public class MyModel
{
public Guid Id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
}
}
A Generic Repository
Notice the event OnChange that is called when something is added/updated/removed. The event is "subscribed" to in a XSockets long running controller (a singleton) See the "RepoMonitor" class
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
namespace SynchronizingCollection.Server.Repository
{
/// <summary>
/// A static generic thread-safe repository for in-memory storage
/// </summary>
/// <typeparam name="TK">Key Type</typeparam>
/// <typeparam name="T">Value Type</typeparam>
public static class Repository<TK, T>
{
/// <summary>
/// When something changes
/// </summary>
public static event EventHandler<OnChangedArgs<TK,T>> OnChange;
private static ConcurrentDictionary<TK, T> Container { get; set; }
static Repository()
{
Container = new ConcurrentDictionary<TK, T>();
}
/// <summary>
/// Adds or updates the entity T with key TK
/// </summary>
/// <param name="key"></param>
/// <param name="entity"></param>
/// <returns></returns>
public static T AddOrUpdate(TK key, T entity)
{
var obj = Container.AddOrUpdate(key, entity, (s, o) => entity);
if(OnChange != null)
OnChange.Invoke(null,new OnChangedArgs<TK, T>(){Key = key,Value = entity, Operation = Operation.AddUpdate});
return obj;
}
/// <summary>
/// Removes the entity T with key TK
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static bool Remove(TK key)
{
T entity;
var result = Container.TryRemove(key, out entity);
if (result)
{
if (OnChange != null)
OnChange.Invoke(null, new OnChangedArgs<TK, T>() { Key = key, Value = entity, Operation = Operation.Remove});
}
return result;
}
/// <summary>
/// Removes all entities matching the expression f
/// </summary>
/// <param name="f"></param>
/// <returns></returns>
public static int Remove(Func<T, bool> f)
{
return FindWithKeys(f).Count(o => Remove(o.Key));
}
/// <summary>
/// Find all entities T matching the expression f
/// </summary>
/// <param name="f"></param>
/// <returns></returns>
public static IEnumerable<T> Find(Func<T, bool> f)
{
return Container.Values.Where(f);
}
/// <summary>
/// Find all entities T matching the expression f and returns a Dictionary TK,T
/// </summary>
/// <param name="f"></param>
/// <returns></returns>
public static IDictionary<TK, T> FindWithKeys(Func<T, bool> f)
{
var y = from x in Container
where f.Invoke(x.Value)
select x;
return y.ToDictionary(x => x.Key, x => x.Value);
}
/// <summary>
/// Returns all entities as a Dictionary TK,T
/// </summary>
/// <returns></returns>
public static IDictionary<TK, T> GetAllWithKeys()
{
return Container;
}
/// <summary>
/// Returns all entities T from the repository
/// </summary>
/// <returns></returns>
public static IEnumerable<T> GetAll()
{
return Container.Values;
}
/// <summary>
/// Get a single entity T with the key TK
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static T GetById(TK key)
{
return Container.ContainsKey(key) ? Container[key] : default(T);
}
/// <summary>
/// Get a single entity T as a KeyValuePair TK,T with the key TK
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static KeyValuePair<TK, T> GetByIdWithKey(TK key)
{
return Container.ContainsKey(key) ? new KeyValuePair<TK, T>(key, Container[key]) : new KeyValuePair<TK, T>(key, default(T));
}
/// <summary>
/// Checks if the repository has a key TK
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static bool ContainsKey(TK key)
{
return Container.ContainsKey(key);
}
}
}
Event argument and an enum to know what change just happend
using System;
namespace SynchronizingCollection.Server.Repository
{
/// <summary>
/// To send changes in the repo
/// </summary>
/// <typeparam name="TK"></typeparam>
/// <typeparam name="T"></typeparam>
public class OnChangedArgs<TK,T> : EventArgs
{
public Operation Operation { get; set; }
public TK Key { get; set; }
public T Value { get; set; }
}
}
namespace SynchronizingCollection.Server.Repository
{
/// <summary>
/// What kind of change was performed
/// </summary>
public enum Operation
{
AddUpdate,
Remove
}
}
The Controller that send changes to the clients...
using System;
using SynchronizingCollection.Common.Model;
using SynchronizingCollection.Server.Repository;
using XSockets.Core.XSocket;
using XSockets.Core.XSocket.Helpers;
using XSockets.Plugin.Framework;
using XSockets.Plugin.Framework.Attributes;
namespace SynchronizingCollection.Server
{
/// <summary>
/// Long running controller that will send information to clients about the collection changes
/// </summary>
[XSocketMetadata(PluginRange = PluginRange.Internal, PluginAlias = "RepoMonitor")]
public class RepositoryMonitor : XSocketController
{
public RepositoryMonitor()
{
Repository<Guid, MyModel>.OnChange += RepositoryOnChanged;
}
private void RepositoryOnChanged(object sender, OnChangedArgs<Guid, MyModel> e)
{
switch (e.Operation)
{
case Operation.Remove:
this.InvokeTo<Demo>(p => p.SendUpdates, e.Value,"removed");
break;
case Operation.AddUpdate:
this.InvokeTo<Demo>(p => p.SendUpdates, e.Value, "addorupdated");
break;
}
}
}
}
The XSockets controller that clients call to add/remove/update the collection.
using System;
using SynchronizingCollection.Common.Model;
using SynchronizingCollection.Server.Repository;
using XSockets.Core.XSocket;
namespace SynchronizingCollection.Server
{
public class Demo : XSocketController
{
public bool SendUpdates { get; set; }
public Demo()
{
//By default all clients get updates
SendUpdates = true;
}
public void AddOrUpdateModel(MyModel model)
{
Repository<Guid, MyModel>.AddOrUpdate(model.Id, model);
}
public void RemoveModel(MyModel model)
{
Repository<Guid, MyModel>.Remove(model.Id);
}
}
}
And a demo client in C# that adds and removed 10 different objects... But it would be easy to use the JavaScript API as well. Especially with knockoutjs for manipulating the collection on the client.
using System;
using System.Threading;
using SynchronizingCollection.Common.Model;
using XSockets.Client40;
namespace SynchronizingCollection.Client
{
class Program
{
static void Main(string[] args)
{
var c = new XSocketClient("ws://127.0.0.1:4502","http://localhost","demo");
c.Controller("demo").OnOpen += (sender, connectArgs) => Console.WriteLine("Demo OPEN");
c.Controller("demo").On<MyModel>("addorupdated", model => Console.WriteLine("Updated " + model.Name));
c.Controller("demo").On<MyModel>("removed", model => Console.WriteLine("Removed " + model.Name));
c.Open();
for (var i = 0; i < 10; i++)
{
var m = new MyModel() {Id = Guid.NewGuid(), Name = "Person Nr" + i, Age = i};
c.Controller("demo").Invoke("AddOrUpdateModel", m);
Thread.Sleep(2000);
c.Controller("demo").Invoke("RemoveModel", m);
Thread.Sleep(2000);
}
Console.ReadLine();
}
}
}
You can download the project from my dropbox: https://www.dropbox.com/s/5ljbedovx6ufkww/SynchronizingCollection.zip?dl=0
Regards
Uffe

Get the exact type as property in C# class

Sorry for the general title but it's a bit hard to explain in few words what is my problem currently.
So I have a simple class factory like this:
public Model Construct<T>(T param) where T : IModelable
{
new Model {Resource = param};
return n;
}
The Model class looks like this:
public class Model
{
public object Resource { get; set; }
}
The problem is, that you can see, is the Resource is currently an object. And I would like that Resource should be the type, what is get from the Construct and not lost the type-safe...
I tried to solve it with type parameter but it fails, because I can extend Model class with type parameter but what if I would like to store it to a simple class repository?
Then Construct will work, but if I would like to get the instanced class from the repository, I have to declare the type paramter again like:
Repository.Get<Model<Spaceship>>(0) .... and of course it's wrong because I would like that Model itself knows, what type of Resource has been added in Construct.
Does anybody any idea how to handle this?
The whole code currently look like this:
/// <summary>
/// Class Repository
/// </summary>
public sealed class Repository
{
/// <summary>
/// The _lock
/// </summary>
private static readonly object _lock = new object();
/// <summary>
/// The _syncroot
/// </summary>
private static readonly object _syncroot = new object();
/// <summary>
/// The _instance
/// </summary>
private static volatile Repository _instance;
/// <summary>
/// The _dict
/// </summary>
private static readonly Dictionary<int, object> _dict
= new Dictionary<int, object>();
/// <summary>
/// Prevents a default data of the <see cref="Repository" /> class from being created.
/// </summary>
private Repository()
{
}
/// <summary>
/// Gets the items.
/// </summary>
/// <value>The items.</value>
public static Repository Data
{
get
{
if (_instance == null)
{
lock (_lock)
{
if (_instance == null) _instance = new Repository();
}
}
return _instance;
}
}
/// <summary>
/// Allocates the specified id.
/// </summary>
/// <param name="id">The id.</param>
/// <param name="parameter">The parameter.</param>
/// <resource name="id">The id.</resource>
/// <resource name="parameter">The parameter.</resource>
public void Allocate(int id, object parameter)
{
lock (_syncroot)
{
_dict.Add(id, parameter);
}
}
/// <summary>
/// Gets the specified id.
/// </summary>
/// <typeparam name="T">The type of the tref.</typeparam>
/// <param name="id">The id.</param>
/// <returns>``0.</returns>
/// <resource name="id">The id.</resource>
public T Get<T>(int id)
{
lock (_syncroot)
{
return (T) _dict[id];
}
}
}
/// <summary>
/// Class IModelFactory
/// </summary>
public sealed class ModelFactory
{
/// <summary>
/// The _lock
/// </summary>
private static readonly object _lock = new object();
/// <summary>
/// The _instance
/// </summary>
private static volatile ModelFactory _instance;
/// <summary>
/// Prevents a default instance of the <see cref="ModelFactory" /> class from being created.
/// </summary>
private ModelFactory()
{
}
/// <summary>
/// Gets the data.
/// </summary>
/// <value>The data.</value>
public static ModelFactory Data
{
get
{
if (_instance == null)
{
lock (_lock)
{
if (_instance == null) _instance = new ModelFactory();
}
}
return _instance;
}
}
/// <summary>
/// Constructs the specified param.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="param">The param.</param>
/// <returns>Model{``0}.</returns>
public Model Construct<T>(T param) where T : IModelable
{
var n = new Model {Resource = param};
return n;
}
}
/// <summary>
/// Class Model
/// </summary>
/// <typeparam name="T"></typeparam>
public class Model
{
public object Resource { get; set; }
}
/// <summary>
/// Interface IModelable
/// </summary>
public interface IModelable
{
/// <summary>
/// Gets or sets the mass.
/// </summary>
/// <value>The mass.</value>
float Mass { get; set; }
}
/// <summary>
/// Class spaceship
/// </summary>
public class Spaceship : IModelable
{
/// <summary>
/// Gets or sets the mass.
/// </summary>
/// <value>The mass.</value>
public float Mass { get; set; }
}
So the problem will be lighted here:
Add to the Repository:
Repository.Data.Allocate(1, ModelFactory.Data.Construct(new Spaceship()));
It's okay, but after:
var test_variable = Repository.Data.Get<Model>(1);
So now I have a non type-safe object from a type parameter, I don't know, that what type of class has been stored with the c model construction.
I'm very thankful for the suggestions of using type paramter on the Model class as well, but than it will come up another problem, because I have to change the Get function with it:
var test_variable = Repository.Data.Get<Model<Spaceship>>(1);
But that's definitely wrong, because I won't know, that what kind of type of class has been stored in the model..., so I would like to achieve to avoid this type parameter definition when I would like to load the instance from the Repository.

You can solve this by making your Model class generic, like this:
public class Model<T>
{
public T Resource { get; set; }
}
Then, your Construct method could work like this:
public Model<T> Construct<T>(T param) where T : IModelable<T>
{
return new Model<T>() {Resource = param};
}

You probably need a generic type in the model class:
public class Model<T>
{
public T Resource { get; set; }
}

This sort of structure is one approach you could take:
public Model<T> Construct<T>(T param) where T : IModelable
{
var n = new Model<T> {Resource = param};
return n;
}
public class Model<T> : IModel<T> where T : IModelable
{
public T Resource { get; set; }
}
public interface IModel<out T> where T : IModelable
{
T Resource { get; }
}
This covariant interface allows you to refer to the types more generically where you wish, in the same way that you can pass an IEnumerable<string> into something expecting an IEnumerable<object>.
IModel<Spaceship> shipModel = // whatever
IModel<IModelable> model = shipModel;
//or even:
List<Model<Spaceship>> shipModels = // whatever
IEnumerable<IModel<IModelable>> models = shipModels;

Can I create a List<Class<T>>?

I have a class
public class Setting<T>
{
public string name { get; set; }
public T value { get; set; }
}
now I want to create an IList<Setting<T>> but with different types of Setting<T>'s T in it, I want e.G.
List<Setting<T>> settingsList;
settingsList.Add(new Setting<int>());
settingsList.Add(new Setting<string>());
I've tried IList<Setting<T>> but this seems not possible since the compiler doesn't find Type T.
I know that I could use object but I want it to be strongly typed. So my question is if there is a possibility of getting this working.

Generic types do not have a common type or interface amongst concrete definitions by default.
Have your Setting<T> class implement an interface (or derive from a common class) and create a list of that interface (or class).
public interface ISetting { }
public class Setting<T> : ISetting
{
// ...
}
// example usage:
IList<ISetting> list = new List<ISetting>
{
new Setting<int> { name = "foo", value = 2 },
new Setting<string> { name = "bar", value "baz" },
};

You have to use a common ancestor class for all the class types that you put into the list. If it should be arbitrary types you have to use object for T

You can use T only inside your class:
class Setting<T>
{
// T is defined here
}
not outside. Outside you need to specify the concrete type:
Settings<string> stringSettings = new Settings<string>();
or
List<Settings<string>> list = new List<Settings<string>>();
list.Add(stringSettings);

ye you can do it by using reflection
i wrote such code for another question but you can use this
public abstract class GenericAccess
{
public static IList<T> GetObjectListFromArray<T>(T item)
{
var r = new List<T>();
var obj = typeof(T).Assembly.CreateInstance(typeof(T).FullName);
var p = obj.GetType().GetProperty("Id", System.Reflection.BindingFlags.IgnoreCase | System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);
if (p != null)
{
p.SetValue(obj, item, null);
var m = r.GetType().GetMethod("Add");
m.Invoke(r, new object[] { obj });
}
return r;
}
}
and call it like this
IList<int> r = GenericAccess.GetObjectListFromArray<int>(1);

/// <summary>
/// 消息回调委托
/// </summary>
/// <typeparam name="T">TClass</typeparam>
/// <param name="result">返回实体</param>
/// <param name="args">内容包</param>
public delegate void CallbackHandler<in T>(T result, BasicDeliverEventArgs args);
/// <summary>
/// 注册监听程序接口
/// </summary>
public interface IRegistration
{
/// <summary>
/// 路由名称
/// </summary>
string ExchangeName { get; }
/// <summary>
/// 路由Key
/// </summary>
string RouteKey { get; }
/// <summary>
/// 回调操作
/// </summary>
/// <param name="args"></param>
void Call(BasicDeliverEventArgs args);
}
/// <summary>
/// 注册监听程序
/// </summary>
/// <typeparam name="T"></typeparam>
public class Registration<T> : IRegistration where T : class
{
/// <summary>
/// 路由名称
/// </summary>
public string ExchangeName { get; set; }
/// <summary>
/// 路由Key
/// </summary>
public string RouteKey { get; set; }
/// <summary>
/// 消息处理器委托
/// </summary>
public CallbackHandler<T> Handler { get; set; }
/// <summary>
/// 接口回调操作
/// </summary>
/// <param name="args"></param>
public void Call(BasicDeliverEventArgs args)
{
var message = Encoding.UTF8.GetString(args.Body.ToArray());
Handler?.Invoke(JsonConvertHandler.DeserializeObject<T>(message), args);
}
}
/// <summary>
/// 消息监听处理器
/// </summary>
public static class ListenerHandler
{
/// <summary>
/// 单任务锁
/// </summary>
private static readonly object Locker = new object();
/// <summary>
/// 所有注册列表
/// </summary>
public static List<IRegistration> Registrations { get; private set; }
/// <summary>
/// 单例化
/// </summary>
static ListenerHandler()
{
List<ListenerSetting> listeners = MqNoticeHandler.Setting.GetListeners();
MqNoticeHandler.Listener(OnMessage, listeners);
}
/// <summary>
/// 注册监听
/// </summary>
/// <param name="registration"></param>
public static void Register(IRegistration registration)
{
lock (Locker)
Registrations.Add(registration);
}
/// <summary>
/// 解除注册
/// </summary>
/// <param name="registration"></param>
public static void UnRegister(IRegistration registration)
{
lock (Locker)
Registrations.Remove(registration);
}
/// <summary>
/// 获取监听列表
/// </summary>
/// <param name="exchangeName"></param>
/// <param name="routeKey"></param>
/// <returns></returns>
public static IEnumerable<IRegistration> GetRegistrations(string exchangeName, string routeKey)
{
return Registrations.Where(x => x.ExchangeName == exchangeName && x.RouteKey == routeKey);
}
/// <summary>
/// 消息回调处理
/// </summary>
/// <param name="consumer">消费者</param>
/// <param name="args">消息包</param>
/// <returns></returns>
private static MqAckResult OnMessage(EventingBasicConsumer consumer, BasicDeliverEventArgs args)
{
//Example Query and Call
Registrations.First().Call(args);
//Return
return new MqAckResult { Accept = true, ReQueue = false };
}
}