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YamlDotNet - Custom Serialization

I have a .NET class which represents a RPC method call, like this:
class MethodCall
{
public string MethodName { get; set; }
public Collection<object> Arguments { get; set; }
}
I want to serialize a Collection<MethodCall> to YAML. I'm using YamlDotNet to achieve this.
By default, YamlDotNet will serialize these objects like this:
methodName: someName
arguments:
- arg1
- arg2
- ...
I would like to simplify the resulting YAML to:
someName:
- arg1
- arg2
Is there any easy way to achieve this? Please note that the arguments can be complex objects (i.e. not simple scalars).

You can achieve this by registering an implementation of IYamlTypeConverter that performs the conversion that you need.
Here's a possible implementation:
public sealed class MethodCallConverter : IYamlTypeConverter
{
// Unfortunately the API does not provide those in the ReadYaml and WriteYaml
// methods, so we are forced to set them after creation.
public IValueSerializer ValueSerializer { get; set; }
public IValueDeserializer ValueDeserializer { get; set; }
public bool Accepts(Type type) => type == typeof(MethodCall);
public object ReadYaml(IParser parser, Type type)
{
parser.Consume<MappingStart>();
var call = new MethodCall
{
MethodName = (string)ValueDeserializer.DeserializeValue(parser, typeof(string), new SerializerState(), ValueDeserializer),
Arguments = (Collection<object>)ValueDeserializer.DeserializeValue(parser, typeof(Collection<object>), new SerializerState(), ValueDeserializer),
};
parser.Consume<MappingEnd>();
return call;
}
public void WriteYaml(IEmitter emitter, object value, Type type)
{
emitter.Emit(new MappingStart());
var call = (MethodCall)value;
ValueSerializer.SerializeValue(emitter, call.MethodName, typeof(string));
ValueSerializer.SerializeValue(emitter, call.Arguments, typeof(Collection<object>));
emitter.Emit(new MappingEnd());
}
}
The converter needs to be registered into the SerializerBuilder and DeserializerBuilder through the WithTypeConverter method. Note that YamlDotNet does not provide us with a way to call the (de)serializer recursively, so we have to set some public properties as a workaround. This is not as clean as it could be, but still works:
string SerializeMethodCall(MethodCall call)
{
var methodCallConverter = new MethodCallConverter();
var serializerBuilder = new SerializerBuilder()
.WithNamingConvention(CamelCaseNamingConvention.Instance)
.WithTypeConverter(methodCallConverter);
methodCallConverter.ValueSerializer = serializerBuilder.BuildValueSerializer();
var serializer = serializerBuilder.Build();
var yaml = serializer.Serialize(call);
return yaml;
}
MethodCall DeserializeMethodCall(string yaml)
{
var methodCallConverter = new MethodCallConverter();
var deserializerBuilder = new DeserializerBuilder()
.WithNamingConvention(CamelCaseNamingConvention.Instance)
.WithTypeConverter(methodCallConverter);
methodCallConverter.ValueDeserializer = deserializerBuilder.BuildValueDeserializer();
var deserializer = deserializerBuilder.Build();
var call = deserializer.Deserialize<MethodCall>(yaml);
return call;
}

Accesing and saving dynamic object

I want send from service to service object:
public abstract class Notification : AggregateRoot
{
public string Title { get; set; }
public string Content { get; set; }
public DateTime Created { get; set; }
public NotificationType NotificationType { get; set; }
}
public class Alert : Notification
{
public object LinkedObject { get; set; }
public bool WasSeen { get; set; }
}
And from my unit test:
[Theory, AutoNSubstituteData]
public async void Send_NotificationIsAlertTypeDocumentDontExist_DocumentShouldBeCreatedAndNotificationSaved(
IDocumentDbRepository<AlertsDocument> repository,
CampaignAlertsSender sender,
Alert notification
)
{
// Arrange
notification.NotificationType = NotificationType.Alert;
notification.LinkedObject = new
{
MerchantId = Guid.NewGuid()
};
repository.GetItemAsync(Arg.Any<Expression<Func<AlertsDocument, bool>>>()).Returns((Task<AlertsDocument>) null);
// Act
await sender.SendAsync(notification);
// Assert
await repository.Received(1).GetItemAsync(Arg.Any<Expression<Func<AlertsDocument, bool>>>());
await repository.Received(1).CreateItemAsync(Arg.Any<AlertsDocument>());
}
Look at the linkedobject it is object but I make it with new. And send it to service.
public override async Task SendAsync(Notification notification)
{
if(notification == null)
throw new ArgumentNullException(nameof(notification));
var alert = notification as Alert;
if(alert == null)
throw new ArgumentException();
var linkedObject = alert.LinkedObject as dynamic;
Guid merchantId = Guid.Parse(linkedObject.MerchantId); // here is problem! linkedObject "object" dont have "MerchantId".
var document = await Repository.GetItemAsync(doc => doc.MerchantId == merchantId);
if (document == null)
{
document = new AlertsDocument
{
MerchantId = merchantId,
Entity = new List<Alert>()
};
document.Entity.Add(alert);
}
}
Here is problem! linkedObject "object" dont have "MerchantId".
But why? While debuging I see the value MerchantId in linkedObject.
How to do it?
Error:
An exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in mscorlib.dll but was not handled in user code
Additional information: 'object' does not contain a definition for 'MerchantId'

LinkedObject is created as an anonymous type which are generated as internal types. If the code accessing the object is not in the same assembly then you will get that error. The debugger can see because it is using reflection but when you try to access it via dynamic you get the error (again because anonymous types are generated as internal).
You however can still get to it via reflection as well.
var linkedObject = alert.LinkedObject as dynamic;
Guid merchantId = (Guid)linkedObject.GetType()
.GetProperty("MerchantId")
.GetValue(linkedObject, null);
but this can get messy very fast.
If you take a look at my answer provided here
How do you unit test ASP.NET Core MVC Controllers that return anonymous objects?
A dynamic wrapper which uses reflection under the hood to access the properties of the anonymous type was used.
The same theory applies and you could probably use that wrapper to access the properties of the linkedObject.
var linkedObject = new DynamicObjectResultValue(alert.LinkedObject);
Guid merchantId = (Guid)linkedObject.MerchantId;

From your code it seems that MerchantId is already a Guid, so you just need to cast it, instead of parsing:
var linkedObject = (dynamic)alert.LinkedObject;
var merchantId = (Guid)linkedObject.MerchantId;

Mocking with moq, trying to pass an object to constructor having multiple parameter

I am trying to mock a method that returns a IEnumerable set of data, like a list of all codes.
There is an Interface ISystemService.cs that contains this method, a service class called SystemService.cs that has the method definition.
System under test is:
public static class CacheKeys
{
public const string ALLCURRENCYCODES = "CurrencyCodes";
}
public interface ICacheManager
{
T Get<T>(string key);
void Set(string key, object data, int cacheTime);
void Clear();
}
public interface ISessionManager
{
}
public interface IApplicationSettings
{
string LoggerName { get; }
int CacheTimeout { get; }
}
public class EFDbContext : DbContext
{
public DbSet<CurrencyCode> CurrencyCodes { get; set; }
}
public class CurrencyCode
{
public string Code { get; set; }
public string Description { get; set; }
public decimal CurrencyUnit { get; set; }
public int? DecimalPlace { get; set; }
public string BaseCurrencyCode { get; set; }
}
public interface ISystemService
{
IEnumerable<CurrencyCode> GetAllCurrencyCodes();
}
//SystemService.cs
public class SystemService : ISystemService
{
private readonly EFDbContext db;
private readonly ICacheManager cacheManager;
private readonly ISessionManager sessionManager;
private readonly IApplicationSettings appSettings;
public SystemService(EFDbContext dbContext, ICacheManager cacheManager, ISessionManager sessionManager, IApplicationSettings appSettings)
{
db = dbContext;
this.cacheManager = cacheManager;
this.sessionManager = sessionManager;
this.appSettings = appSettings;
}
public IEnumerable<CurrencyCode> GetAllCurrencyCodes()
{
var allCurrencyCodes = cacheManager.Get<IEnumerable<CurrencyCode>>(CacheKeys.ALLCURRENCYCODES);
if (allCurrencyCodes == null)
{
allCurrencyCodes = db.CurrencyCodes.ToList();
cacheManager.Set(CacheKeys.ALLCURRENCYCODES, allCurrencyCodes, appSettings.CacheTimeout);
}
return allCurrencyCodes;
}
Test Method
[TestMethod]
public void testCacheMiss()
{
List<CurrencyCode> currencycodes = new List<CurrencyCode>()
{
new CurrencyCode(){Id = 1, Code = "IND", Description = "India"},
new CurrencyCode(){Id = 2, Code = "USA", Description = "UnitedStates"},
new CurrencyCodes(){Id = 3, Code = "UAE", Description = "ArabEmirates"}
};
var mockEfContext = new Mock<EFDbContext>();
var mockCacheManager = new Mock<ICacheManager>();
var mockSessionManager = new Mock<ISessionManager>();
var mockAppSettings = new Mock<IApplicationSettings>();
// Setups for relevant methods of the above here, e.g. to test a cache miss
mockEfContext.SetupGet(x => x.CurrencyCodes)
.Returns(currencycodes); // Canned currencies
mockCacheManager.Setup(x => x.Get<IEnumerable<CurrencyCode>>(It.IsAny<string>()))
.Returns<IEnumerable<CurrencyCodes>>(null); // Cache miss
// Act
var service = new SystemService(mockEfContext.Object, mockCacheManager.Object,
mockSessionManager.Object, mockAppSettings.Object);
var codes = service.GetAllCodes();
// Assert + Verify
mockCacheManager.Verify(x => x.Get<IEnumerable<CurrencyCodes>>(
It.IsAny<string>()), Times.Once, "Must always check cache first");
mockEfContext.VerifyGet(x => x.CurrencyCodes,
Times.Once, "Because of the simulated cache miss, must go to the Db");
Assert.AreEqual(currencycodes.Count, codes.Count(), "Must return the codes as-is");
Since the defined constructor does not accept one parameter, how to pass the object as parameter? Please advice

If CodeService is under test, then you want to be mocking its dependencies, not the CodeService itself.
You'll need to provide Mocks for all of the dependencies of CodeService to the constructor, i.e.:
var currencycodes = new List<SomeCodes>
{
new CurrencyCodes(){Id = 1, Code = "IND", Description = "India"},
new CurrencyCodes(){Id = 2, Code = "USA", Description = "UnitedStates"},
new CurrencyCodes(){Id = 3, Code = "UAE", Description = "ArabEmirates"}
};
var mockEfContext = new Mock<EFDbContext>();
var mockCacheManager = new Mock<ICacheManager>();
var mockSessionManager = new Mock<ISessionManager>();
var mockAppSettings = new Mock<IApplicationSettings>();
// Setups for relevant methods of the above here, e.g. to test a cache miss
mockEfContext.SetupGet(x => x.SomeCodes)
.Returns(currencycodes); // Canned currencies
mockCacheManager.Setup(x => x.Get<IEnumerable<SomeCodes>>(It.IsAny<string>()))
.Returns<IEnumerable<SomeCodes>>(null); // Cache miss
// Act
var service = new CodeService(mockEfContext.Object, mockCacheManager.Object,
mockSessionManager.Object, mockAppSettings.Object);
var codes = service.GetAllCodes();
// Assert + Verify
mockCacheManager.Verify(x => x.Get<IEnumerable<SomeCodes>>(
It.IsAny<string>()), Times.Once, "Must always check cache first");
mockEfContext.VerifyGet(x => x.SomeCodes,
Times.Once, "Because of the simulated cache miss, must go to the Db");
Assert.AreEqual(currencycodes.Count, codes.Count(), "Must return the codes as-is");
Edit If you however mean that the next layer up of your code is under test, the principal is the same:
var mockCodeService = new Mock<ICodeService>();
mockCodeService.Setup(x => x.GetAllCodes())
.Returns(currencycodes); // Now we don't care whether this is from cache or db
var higherLevelClassUsingCodeService = new SomeClass(mockCodeService.Object);
higherLevelClassUsingCodeService.DoSomething();
mockCodeService.Verify(x => x.GetAllCodes(), Times.Once); // etc
Edit 2
I've fixed a couple of typos in the code, and assuming CurrencyCodes inherits SomeCodes and that your cache key is a string, and pushed it up onto a Git Gist here with the corresponding cache miss unit test as well. (I've used NUnit, but it isn't really relevant here)

allCodes is your service.. its the mock you need to be working with. You shouldn't be creating a concrete instance of your ICodeService.. your mock exists to fill that role.
So, remove this:
var service = new CodeService(allCodes.object);
Your next line should be:
var code = allCodes.Object.GetAllCodes();
But then.. this test seems completely redundant after that.. since you appear to be testing your mock..
Also, allCodes should be called serviceMock.. as that makes more sense.

Find all classes which derive from a specific base class and add them to the registry

I have a base class called BaseStatus which looks like this:
public class BaseStatus
{
public int UnitId { get; protected set; }
public UInt16 StatusValue { get; protected set; }
public string StatusCode { get; protected set; }
public string StatusDescription { get; protected set; }
public BaseStatus()
{
this.UnitId = -1;
this.StatusValue = 0;
this.StatusCode = null;
this.StatusDescription = null;
}
}
Furthermore i have two or more other base classes which derive from BaseStatus and define a other unit id. For example the two classes
public class BaseGlobalStatus : BaseStatus
{
public BaseGlobalStatus()
{
base.UnitId = -1;
}
}
public class BaseGcmGdmStatus : BaseStatus
{
public BaseGcmGdmStatus()
{
base.UnitId = 2;
}
}
public class BaseCcuStatus : BaseStatus
{
public BaseCcuStatus()
{
base.UnitId = 1;
}
}
The Background is that i want to derive from for example BaseCcuStatus and have the correct UnitId in the derived class.
Now i define my correct status classes for example:
public class StatStErrDefinition : BaseGlobalStatus
{
public StatStErrDefinition()
: base()
{
base.StatusDescription = "Kommando nicht zulässig, unit im state ERROR";
base.StatusCode = "STAT_ST_ERR";
base.StatusValue = 3;
}
}
public class GcmStErrDefinition : BaseGcmGdmStatus
{
public GcmStErrDefinition()
: base()
{
base.StatusDescription = "Kommando nicht zulässig, unit im state ERROR";
base.StatusCode = "STAT_ST_ERR";
base.StatusValue = 3;
}
}
public class CcuStErrDefinition : BaseCcuStatus
{
public CcuStErrDefinition()
: base()
{
base.StatusDescription = "Kommando nicht zulässig, unit im state ERROR";
base.StatusCode = "STAT_ST_ERR";
base.StatusValue = 3;
}
}
For my understading, the three classes StatStErrDefinition, GcmStErrDefinition and CcuStErrDefinition should have the UnitId which is set in the derived BaseClass?
Now that i have defined my three Status Classes i want to get them into a registry. Currently im using this piece of code to try get them. Problem is that the result has no items.
registry = new StatusDictionary<UInt16, BaseStatus>();
var unitStatus = typeof(BaseStatus)
.Assembly.GetTypes()
.Where(x => x.BaseType == typeof(BaseStatus))
.Select(x => new
{
StatusType = x,
UnitId = x.GetProperty("UnitId", BindingFlags.Public)
StatVal = x.GetProperty("StatusValue", BindingFlags.Public)
}
)
.Where(x => x.StatVal != null && x.UnitId != null)
.Select(x => new
{
UnitId = (int)x.UnitId.GetValue(null, null),
StatusValue = (UInt16)x.StatVal.GetValue(null, null),
Factory = (Func<BaseStatus>)(() => ((BaseStatus)Activator.CreateInstance(x.StatusType)))
});
try
{
foreach (var status in unitStatus)
{
if (status.UnitId == unitId
|| status.UnitId < 0)
registry.Register(status.StatusValue, status.Factory);
}
}
catch (Exception ex)
{
string temp = ex.Message;
}
After the LINQ expression the var unitStatus is empty...
Later, the registry call looks like that to get the specific class but that is unimportant at this point:
stat = StatusContainer.GetRegistry(this.unitTypeId).GetInstance(this.StatusValue);
For information:
I want to get the status class which should be in the registry by the unittypeid and the specific status value.
Currently my registry method does not work because he is not able to find any class. So there has to be a mistake somewhere. Thanks in advance
#Update 1
I changed my functionality a little bit:
registry = new StatusDictionary<UInt16, BaseStatus>();
//get all types of cucrent assembly
var allAssemblyTypes = Assembly.GetCallingAssembly().GetTypes();
//get all types from base status
var baseStatusTypes = allAssemblyTypes.Where(x => x.BaseType == typeof(BaseStatus));
//Place all concrete types in the foundtypes
List<Type> foundTypes = new List<Type>();
foreach (Type item in baseStatusTypes)
{
var temp = allAssemblyTypes.Where(x => x.BaseType == item)
.Select(x => new
{
StatusType = x,
UnitId = x.GetProperty("UnitId", BindingFlags.Public),
StatVal = x.GetProperty("StatusValue", BindingFlags.Public),
}
);
}
Temp contains now the correct type.
Problem is that if temp is type of StatStErrDefinition the StatusValue and UnitId Property is null.
The fact is that these members are instance members. Is there a way to get the values out of them?

First thing first : your LINQ query is pretty long.
divide it in different step and store them in different variables (or make properties out of them, whatever you prefer)
This is
easy to read / maintain
easy to debug
With this given I think you are able to solve your problem :)
To check if the class is of a certain type you could use the method .OfType
Use this method to get the value. Notice that you must make an instance in your case because the value change in your constructor.
public static object GetPropValue(Type src, string propName)
{
var prop = src.GetProperty(propName);
var instance = Activator.CreateInstance(src);
var value = prop.GetValue(instance);
return value;
}
Instead of
UnitId = x.GetProperty("UnitId", BindingFlags.Public),
use
UnitId = GetPropValue(x,"UnitId"),

C# Looking for pattern ideas - Inheritance w/ constructor issue

I have a multiple layered application I'm rewriting using Entity Framework 4 w/ Code First. The important things:
In the data layer, on my context, I have:
public DbSet<MobileSerialContainer> Mobiles { get; set; }
This context has a static instance. I know, I know, terrible practice. There are reasons which aren't relevant to this post as to why I'm doing this.
MobileSerialContainer consists of the following:
[Table("Mobiles")]
public sealed class MobileSerialContainer
{
[Key]
public long Serial { get; set; }
[StringLength(32)]
public string Name { get; set; }
public MobileSerialContainer() { }
public MobileSerialContainer(Mobile mobile)
{
Mobile = mobile;
LeContext.Instance.Mobiles.Add(this);
}
[StringLength(1024)]
public string FullClassName
{
get { return Mobile == null ? "" : Mobile.GetType().AssemblyQualifiedName; }
set
{
if (string.IsNullOrEmpty(value) || value == FullClassName)
return;
Mobile = null;
var type = Type.GetType(value);
if (type == null)
return;
if (!type.IsSubclassOf(typeof(Mobile))
&& type != typeof(Mobile))
return;
var constructor = type.GetConstructor(new [] { GetType() });
// The problem here is that Person ( which extends mobile ) does not have a constructor that takes a MobileSerialContainer.
// This is a problem of course, because I want to make this entire layer transparent to the system, so that each derivative
// of Mobile does not have to implement this second constructor. Blasphemy!
if (constructor == null)
return;
Mobile = (Mobile)constructor.Invoke(new object[] { this });
}
}
public string SerializedString
{
get
{
return Mobile == null ? "" : Mobile.Serialize();
}
set
{
if (Mobile == null)
return;
if (string.IsNullOrEmpty(value))
return;
Mobile.Deserialize(value);
}
}
[NotMapped]
public Mobile Mobile { get; set; }
public void Delete()
{
LeContext.Instance.Mobiles.Remove(this);
}
}
Now... I know this is a long post bear with me. Mobile is this:
public class Mobile
{
public long Serial { get { return Container.Serial; } }
public string Name { get { return Container.Name; } set { Container.Name = value; } }
public Mobile()
{
Container = new MobileSerialContainer(this);
}
public Mobile(MobileSerialContainer container)
{
Container = container;
}
public void Delete()
{
Container.Delete();
}
private MobileSerialContainer Container { get; set; }
protected static string MakeSafeString(string value)
{
if (string.IsNullOrEmpty(value))
return value;
return value.Replace("&", "&")
.Replace(",", "&comma;")
.Replace("=", "&eq;");
}
protected static string MakeUnsafeString(string value)
{
if (string.IsNullOrEmpty(value))
return value;
return value.Replace("&eq;", "=")
.Replace("&comma;", ",")
.Replace("&", "&");
}
public virtual string Serialize()
{
string result = "";
var properties = PersistentProperties;
foreach (var property in properties)
{
string name = MakeSafeString(property.Name);
var value = property.GetValue(this, null);
string unsafeValueString = (string)Convert.ChangeType(value, typeof(string));
string valueString = MakeSafeString(unsafeValueString);
result += name + "=" + valueString + ",";
}
return result;
}
public virtual void Deserialize(string serialized)
{
var properties = PersistentProperties.ToList();
var entries = serialized.Split(',');
foreach (var entry in entries)
{
if (string.IsNullOrEmpty(entry))
continue;
var keyPair = entry.Split('=');
if (keyPair.Length != 2)
continue;
string name = MakeUnsafeString(keyPair[0]);
string value = MakeUnsafeString(keyPair[1]);
var property = properties.FirstOrDefault(p => p.Name == name);
if (property == null)
continue;
object rawValue = Convert.ChangeType(value, property.PropertyType);
property.SetValue(this, rawValue, null);
}
}
protected IEnumerable<PropertyInfo> PersistentProperties
{
get
{
var type = GetType();
var properties = type.GetProperties().Where(p => p.GetCustomAttributes(typeof(PersistAttribute), true).Any());
return properties;
}
}
}
Several layers above this, I have the System layer, in which I have the class Person:
public class Person : Mobile
{
[Persist]
public string LastName { get; set; }
}
The basic idea is this: I want the System layer to have almost no knowledge of the Data layer. It creates anything that extends "Mobile", which is automatically saved to the database. I don't want to have a table for Person, hence the weird serialization stuff, because there are literally hundreds of classes that extend Mobile. I don't want hundreds of tables. All of this serialization stuff works perfectly, the SerializedString bit, saving everything, reloading, etc etc. The only thing I haven't come up with a solution for is:
I don't want to have to implement the two constructors to Person:
public Person() : base() { }
public Person(MobileSerialContainer container)
: base(container) { }
as that requires the System layer to have more knowledge of the Data layer.
The weird serialization string thing stays. The reflection business stays. I know it's slow, but database writes and reads are very rare, and asynchronous anyway.
Besides that, I'm looking for any cool ideas about how to resolve this. Thanks!
[edit]
Changed a miswritten line of code in the MobileSerialContainer class pasted here.

If you are rewriting your application, you could reconsider all the design of your system to keep your domain layer (System layer) independent from your Data Access layer using :
A repository pattern to handle access to your database (dataContext)
A domain layer for your business objects (mobile and stuff)
Inversion Of Control pattern (IOC) to keep your layers loosely coupled
The inheritance stuff is definitively not the good way to go to keep a system loosely coupled.

What you want is type.GetConstructors() not type.GetConstructor(), this will let you get the base constructors and pass the type you are looking for.