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ASP.NET C# OData Service + Navigation Property + $expand = null. What am I missing?

I will try to explain my problem as thoroughly as possible with a simplified example. Please note that I am NOT using Entity Framework.
I have this model:
public class Person
{
[Key]
public Guid Id { get; set; }
public string GivenName { get; set; }
public string FamilyName { get; set; }
public List<Employment> Employments { get; set; }
}
public class Employment
{
public string Role { get; set; }
public Guid? ManagerId { get; set; }
public virtual Person Manager { get; set; }
}
I create an in-memory data source:
public class MyDataSource
{
private static MyDataSource instance = null;
public static MyDataSource Instance
{
get
{
if (instance == null)
{
instance = new MyDataSource();
}
return instance;
}
}
public List<Person> Persons { get; set; }
private MyDataSource()
{
this.Persons = new List<Person>();
this.Persons.AddRange(new List<Person>
{
new Person()
{
Id = Guid.Parse("00000000-0000-0000-0000-000000000001"), //Just for simplicity
GivenName = "John",
FamilyName = "Doe",
Employments = new List<Employment>()
{
new Employment()
{
Role = "Boss"
}
}
},
new Person()
{
Id = Guid.Parse("00000000-0000-0000-0000-000000000002"), //Just for simplicity
GivenName = "Clark",
FamilyName = "Kent",
Employments = new List<Employment>()
{
new Employment()
{
Role = "Worker",
ManagerId = Guid.Parse("00000000-0000-0000-0000-000000000001"), //Just for simplicity
}
}
}
});
}
}
I have this controller:
[EnableQuery]
public class PersonsController : ODataController
{
public IHttpActionResult Get()
{
return Ok(MyDataSource.Instance.Persons)
}
}
I configure the EndPoint:
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
config.MapODataServiceRoute("ODataRoute", "odata", CreateEdmModel());
config.Select().Expand().Filter().OrderBy().MaxTop(null).Count()
}
public static IEdmModel CreateEdmModel()
{
var builder = new ODataConventionModelBuilder();
var persons = builder.EntitySet<Person>("Persons");
builder.ComplexType<Employment>().HasOptional(e => e.Manager, (e, p) => e.ManagerId == p.Id);
return builder.GetEdmModel();
}
}
Checking the $metadata I see this:
<NavigationProperty Name="Manager" Type = "MyNamespace.Person">
<ReferentialConstraint Property="ManagerId" ReferenceProperty="Id" />
</NavigationProperty
Everything looks fine from what I can tell but:
https://example.com/odata/persons?$expand=Employments/Manager
receives everything fine but:
Manager is null for both persons. I was expecting to see John Doe on Clark Kents employment.
What am I missing?

I have solved it myself.
I realised that it doesn't work like I thought and that I have to add a reference to the manager directly in MyDataSource. After that it works to $expand the manager.

trying to print the contents of a list when using list<class>

I have a class with two variables: Name, Address
I instantiate the class, add values to it, and try to store it in a list. Once I do that I hope to print the Name and Adress on the console but I'm not sure what I'm doing wrong:
public class Test
{
public string Name { set; get; }
public string Address { set; get; }
}
static void Main(string[] args)
{
Test t = new Test();
t.Name = "bob";
t.Address = "CT";
List<Test> lst = new List<Test>();
lst.Add(t);
foreach (var x in lst)
{
Console.WriteLine(x);
}
}
WHen I do this I simply get the name of my project.ClassName

Simply, override ToString and everything else should work as you'd expect it to.
Example:
class Test
{
public string Name { set; get; }
public string Address { set; get; }
public override string ToString(){
return $"name: {Name}, address: {Address}";
}
}

You can utilize the ToString in your class. When passed your class-instance to the Console.WriteLine function, this ToString-function is called.
For further information check the documentation for Console.WriteLine and object.ToString().
public class Test
{
public string Name { set; get; }
public string Address { set; get; }
public override string ToString()
{
return $"Name: {Name} Address: {Address}";
}
}
static void Main(string[] args)
{
Test t = new Test();
t.Name = "bob";
t.Address = "CT";
List<Test> lst = new List<Test>();
lst.Add(t);
foreach (var x in lst)
{
Console.WriteLine(x);
}
}
This will output:
Name: bob Address: CT

You need to access the Name property inside for loop
foreach (var x in lst)
{
Console.WriteLine(x.Name);
}

for me i will use this
static void Main(string[] args)
{
Test t = new Test();
t.Name = "bob";
t.Address = "CT";
List<Test> lst = new List<Test>();
lst.Add(t);
lst.ForEach(show);
}
private static void show(Test obj)
{
Console.WriteLine(obj.Name);
Console.WriteLine(obj.Address);
}

If you want to have it print the properties dynamically whenever the class is updated, you can use Json.Net.
class Test
{
public string Name { set; get; }
public string Address { set; get; }
public override string ToString()
{
return JsonConvert.SerializeObject(this);
}
}

NSubstitute: Difference between Substitute.For<> and Substitute.ForPartsOf

I'm using NSubstitute. I have to fake a class and cannot dig out the difference of Substitute.For<...>() and Substitute.ForPartsOf<...>. I already read the documentation but don`t get the point, where the two behave different.

Substitute.For<>() creates full mock, while Substitute.ForPartsOf<> creates partial mock. For example:
[Test]
public void Test()
{
var person = Substitute.For<Person>();
person.GetAge().Returns(20);
var age = person.GetAge(); //returns 20
var name = person.GetName(); //returns empty string
var partialPerson = Substitute.ForPartsOf<Person>();
partialPerson.GetAge().Returns(20);
var age2 = partialPerson.GetAge(); //returns 20
var name2 = partialPerson.GetName(); //returns John
}
public class Person
{
public string Name { get; } = "John";
public int Age { get; } = 10;
public virtual int GetAge()
{
return Age;
}
public virtual string GetName()
{
return Name;
}
}
Generally ForPartsOf<> will use concrete implementation if it has not been substituted.

Moq: Mock SetUp method only returns null during test

I just added dependency inject into my application, and would like to run mock test on my methods to ensure they are working properly.
I have a domain class Person with the following properties:
public class Person : DomainBase
{
public string FirstName { get; set; }
public string LastName { get; set; }
public char Gender { get; set; }
public DateTime DOB {get; set; }
}
I have a partial manager class that is shared with other domain type mangers:
public partial class Manager : IManager1
{
private IHiveTiesContext _ctx;
public Manager(IHiveTiesContext context)
{
_ctx = context;
}
}
The interface IManager1 was extracted from my PersonManager class and contains all need methods.
My PersonManager CreatePerson() method is being called and tested:
public partial class Manager : IManager1
{
public Person CreatePerson(string fn, string ln, DateTime dob, char gender, Guid RId)
{
var _person =_ctx.People.Add(new Person
{
FirstName = fn,
LastName = ln,
DOB = dob,
Gender = gender,
RowId = RId});
_ctx.SaveChanges();
return _person;
}
}
}
My context follows and once again I extracted an interface IHiveTiesContext from it.
public class HiveTiesContext : DbContext, IHiveTiesContext
{
public HiveTiesContext() : base("hiveties")
{
Database.SetInitializer<HiveTiesContext>(null);
}
public virtual IDbSet<Person> People { get; set; }
}
Finally I am trying to test CreatePerson like this:
public class PersonManagerMockTest
{
private static Guid personGuid;
[ClassInitialize]
public static void Init(TestContext test)
{
personGuid = Guid.NewGuid();
}
[TestMethod]
public void AddNewPerson()
{
//Arrange
var mockDbSet = new Mock<DbSet<Person>>();
var mockContext = new Mock<IHiveTiesContext>();
mockContext.Setup(x => x.People)
.Returns(mockDbSet.Object);
var manager = new Manager(mockContext.Object);
//Assert
var _person = manager.CreatePerson("Winston", "Gabriel", DateTime.Now, 'M', personGuid);
if(_person == null)
{
throw new Exception("NOT WORKING MAN!!!!");
}
var personid = mockContext.Object.People.Single(x => x.RowId == personGuid).Id;
//Act
mockDbSet.Verify(x => x.Add(It.IsAny<Person>()));
mockContext.Verify(x => x.SaveChanges());
}
}
My problem is that my Person object is never created, that is, it always returns a null value and the exception is always thrown. I believe I am telling it to return a Person entity, but I am not sure where I am going wrong. This is my first time using Moq and running Mock Unit Tests.
I appreciate any suggestions. Thank you.

You didn't set any behavior on the Add method of mockDbSet.
Add:(This line initialize the method to return the given person)
mockDbSet.Setup(x => x.Add(It.IsAny<Person>()))
.Returns <Person>(p => p);
Between the mocks:
var mockDbSet = new Mock<DbSet<Person>>();
mockDbSet.Setup(x => x.Add(It.IsAny<Person>()))
.Returns<Person>(p => p);
var mockContext = new Mock<IHiveTiesContext>();
mockContext.Setup(x => x.People)
.Returns(mockDbSet.Object);
...

I created a new signature/function in IHiveTiesContext to save Person object. (It's up to you now how you implement the interface).
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace SampleManager
{
public class Manager : IManager
{
private IHiveTiesContext _ctx;
public Manager(IHiveTiesContext context)
{
_ctx = context;
}
public Person CreatePerson(string fn, string ln, DateTime dob, char gender, Guid RId)
{
var person = _ctx.Save(fn, ln);
return person;
}
}
public class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
public char Gender { get; set; }
public DateTime DOB { get; set; }
public Guid RowId { get; set; }
}
public interface IManager
{
Person CreatePerson(string fn, string ln, DateTime dob, char gender, Guid RId);
}
public interface IHiveTiesContext
{
Person Save(string fn, string ln);
}
}
/// <summary>
///A test for CreatePerson
///</summary>
[TestMethod()]
public void CreatePersonTest1()
{
var mock = new Mock<IHiveTiesContext>();
//fill up your expected object
mock.Setup(m => m.Save(It.IsAny<string>(), It.IsAny<string>())).Returns(new Person { FirstName = "William" });
Manager t = new Manager(mock.Object);
var results = t.CreatePerson(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<DateTime>(), It.IsAny<Char>(), It.IsAny<Guid>());
Assert.AreEqual("William", results.FirstName);
}

In C#, how to instantiate a passed generic type inside a method?

How can I instantiate the type T inside my InstantiateType<T> method below?
I'm getting the error: 'T' is a 'type parameter' but is used like a 'variable'.:
(SCROLL DOWN FOR REFACTORED ANSWER)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace TestGeneric33
{
class Program
{
static void Main(string[] args)
{
Container container = new Container();
Console.WriteLine(container.InstantiateType<Customer>("Jim", "Smith"));
Console.WriteLine(container.InstantiateType<Employee>("Joe", "Thompson"));
Console.ReadLine();
}
}
public class Container
{
public T InstantiateType<T>(string firstName, string lastName) where T : IPerson
{
T obj = T();
obj.FirstName(firstName);
obj.LastName(lastName);
return obj;
}
}
public interface IPerson
{
string FirstName { get; set; }
string LastName { get; set; }
}
public class Customer : IPerson
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Company { get; set; }
}
public class Employee : IPerson
{
public string FirstName { get; set; }
public string LastName { get; set; }
public int EmployeeNumber { get; set; }
}
}
REFACTORED ANSWER:
Thanks for all the comments, they got me on the right track, this is what I wanted to do:
using System;
namespace TestGeneric33
{
class Program
{
static void Main(string[] args)
{
Container container = new Container();
Customer customer1 = container.InstantiateType<Customer>("Jim", "Smith");
Employee employee1 = container.InstantiateType<Employee>("Joe", "Thompson");
Console.WriteLine(PersonDisplayer.SimpleDisplay(customer1));
Console.WriteLine(PersonDisplayer.SimpleDisplay(employee1));
Console.ReadLine();
}
}
public class Container
{
public T InstantiateType<T>(string firstName, string lastName) where T : IPerson, new()
{
T obj = new T();
obj.FirstName = firstName;
obj.LastName = lastName;
return obj;
}
}
public interface IPerson
{
string FirstName { get; set; }
string LastName { get; set; }
}
public class PersonDisplayer
{
private IPerson _person;
public PersonDisplayer(IPerson person)
{
_person = person;
}
public string SimpleDisplay()
{
return String.Format("{1}, {0}", _person.FirstName, _person.LastName);
}
public static string SimpleDisplay(IPerson person)
{
PersonDisplayer personDisplayer = new PersonDisplayer(person);
return personDisplayer.SimpleDisplay();
}
}
public class Customer : IPerson
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Company { get; set; }
}
public class Employee : IPerson
{
public string FirstName { get; set; }
public string LastName { get; set; }
public int EmployeeNumber { get; set; }
}
}

Declare your method like this:
public string InstantiateType<T>(string firstName, string lastName)
where T : IPerson, new()
Notice the additional constraint at the end. Then create a new instance in the method body:
T obj = new T();

Couple of ways.
Without specifying the type must have a constructor:
T obj = default(T); //which will produce null for reference types
With a constructor:
T obj = new T();
But this requires the clause:
where T : new()

To extend on the answers above, adding where T:new() constraint to a generic method will require T to have a public, parameterless constructor.
If you want to avoid that - and in a factory pattern you sometimes force the others to go through your factory method and not directly through the constructor - then the alternative is to use reflection (Activator.CreateInstance...) and keep the default constructor private. But this comes with a performance penalty, of course.

you want new T(), but you'll also need to add , new() to the where spec for the factory method

A bit old but for others looking for a solution, perhaps this could be of interest: http://daniel.wertheim.se/2011/12/29/c-generic-factory-with-support-for-private-constructors/
Two solutions. One using Activator and one using Compiled Lambdas.
//Person has private ctor
var person = Factory<Person>.Create(p => p.Name = "Daniel");
public static class Factory<T> where T : class
{
private static readonly Func<T> FactoryFn;
static Factory()
{
//FactoryFn = CreateUsingActivator();
FactoryFn = CreateUsingLambdas();
}
private static Func<T> CreateUsingActivator()
{
var type = typeof(T);
Func<T> f = () => Activator.CreateInstance(type, true) as T;
return f;
}
private static Func<T> CreateUsingLambdas()
{
var type = typeof(T);
var ctor = type.GetConstructor(
BindingFlags.Instance | BindingFlags.CreateInstance |
BindingFlags.NonPublic,
null, new Type[] { }, null);
var ctorExpression = Expression.New(ctor);
return Expression.Lambda<Func<T>>(ctorExpression).Compile();
}
public static T Create(Action<T> init)
{
var instance = FactoryFn();
init(instance);
return instance;
}
}

You can also use reflection to fetch the object's constructor and instantiate that way:
var c = typeof(T).GetConstructor();
T t = (T)c.Invoke();

Using a factory class to build your object with compiled lamba expression: The fastest way I've found to instantiate generic type.
public static class FactoryContructor<T>
{
private static readonly Func<T> New =
Expression.Lambda<Func<T>>(Expression.New(typeof (T))).Compile();
public static T Create()
{
return New();
}
}
Here is the steps I followed to set up the benchmark.
Create my benchmark test method:
static void Benchmark(Action action, int iterationCount, string text)
{
GC.Collect();
var sw = new Stopwatch();
action(); // Execute once before
sw.Start();
for (var i = 0; i <= iterationCount; i++)
{
action();
}
sw.Stop();
System.Console.WriteLine(text + ", Elapsed: {0}ms", sw.ElapsedMilliseconds);
}
I've also tried using a factory method:
public static T FactoryMethod<T>() where T : new()
{
return new T();
}
For the tests I've created the simplest class :
public class A { }
The script to test:
const int iterations = 1000000;
Benchmark(() => new A(), iterations, "new A()");
Benchmark(() => FactoryMethod<A>(), iterations, "FactoryMethod<A>()");
Benchmark(() => FactoryClass<A>.Create(), iterations, "FactoryClass<A>.Create()");
Benchmark(() => Activator.CreateInstance<A>(), iterations, "Activator.CreateInstance<A>()");
Benchmark(() => Activator.CreateInstance(typeof (A)), iterations, "Activator.CreateInstance(typeof (A))");
Results over 1 000 000 iterations:
new A(): 11ms
FactoryMethod A(): 275ms
FactoryClass A .Create(): 56ms
Activator.CreateInstance A (): 235ms
Activator.CreateInstance(typeof (A)): 157ms
Remarks: I've tested using both .NET Framework 4.5 and 4.6 (equivalent results).

Instead of creating a function to Instantiate the type
public T InstantiateType<T>(string firstName, string lastName) where T : IPerson, new()
{
T obj = new T();
obj.FirstName = firstName;
obj.LastName = lastName;
return obj;
}
you could have done it like this
T obj = new T { FirstName = firstName, LastName = lastname };