Develop Reference

What design pattern should use in this case?

I have big model, that aggragates data for buisness entity.
class BigObject
{
TypeA DataA { get;set; }
TypeB DataB { get;set; }
TypeC DataC { get;set; }
}
and have service, which fill fields of model from differents sources. Some data depends from another data
class DataService
{
public BigObject GetModel()
{
var model = new BigObject();
model.DataA = sourceServiceA.GetData();
model.DataB = sourceServiceB.GetData(model.DataA.Id);
model.DataC = sourceServiceC.GetData();
}
}
In method GetModel() I need to configure, which fields should be filled, which should not. For example, I want to fill DataA property, but don't want fill others. First idea is pass in method object BigObjectFilter
public BigObject GetModel(BigObjectFilter filter)
class BigObjectFilter
{
bool FillDataA { get; set; }
bool FillDataB { get; set; }
bool FillDataC { get; set; }
}
and initialize this object in DataService clients.
In GetObject method I was going to add conditions like
if (filter.FillDataA)
{
model.DataA = sourceServiceA.GetData();
}
if (filter.FillDataC)
{
model.DataC = sourceServiceC.GetData();
}
I see, that this solution looks like bad practice. I would like to improve this construction. How can i improve it? I can't see, how to use builder pattern in this case, because i have requeired and optional data, one depends on the other.

For the sake of simplicity let's assume that TypeA, TypeB and TypeC are int?.
We can define a command class for the BigObject with the following constructors:
class BigObjectCommand
{
private readonly Func<BigObjectFilter, bool> canExecute;
private readonly Action<BigObject>? executeWithoutParam;
private readonly Action<int, BigObject>? executeWithParam;
private readonly Expression<Func<BigObject, int?>>? dependsOn;
public BigObjectCommand(Func<BigObjectFilter, bool> canExecute, Action<BigObject> execute)
{
this.canExecute = canExecute;
this.executeWithoutParam = execute;
}
public BigObjectCommand(Func<BigObjectFilter, bool> canExecute, Action<int, BigObject> execute, Expression<Func<BigObject, int?>> dependsOn)
{
this.canExecute = canExecute;
this.executeWithParam = execute;
this.dependsOn = dependsOn;
}
}
The first constructor will be used to cover the DataA and DataC properties' initialization
The second constructor will be used to cover the initialization of DataB property
Now, we can define an Evaluate method to implement the core logic
public void Evaluate(BigObjectFilter filter, BigObject context)
{
if (!canExecute(filter))
return; //or throw exception
if (executeWithoutParam is not null)
{
executeWithoutParam(context);
return;
}
var input = dependsOn!.Compile()(context);
if (!input.HasValue)
return; //or throw exception
executeWithParam!(input.Value, context);
}
If the condition fails we don't do the assignment
If the assignment does not require any input then we simply execute it
If the assignment depends on an input then we check whether it is populated or not and depending on the result we may or may not execute the assignment
With these in our hand the GetModel can be implemented like this:
private readonly List<BigObjectCommand> Commands;
public DataService()
{
Commands = new()
{
new (filter => filter.FillDataA, (m) => m.DataA = sourceServiceA.GetData()),
new (filter => filter.FillDataB, (i, m) => m.DataB = sourceServiceB.GetData(i), m => m.DataA),
new (filter => filter.FillDataC, (m) => m.DataC = sourceServiceC.GetData()),
};
}
public BigObject GetModel(BigObjectFilter filter)
{
var model = new BigObject();
foreach (var command in Commands)
{
command.Evaluate(filter, model);
}
return model;
}
This solution is far from perfect I just wanted to share with you the basic idea how to apply the Command pattern for your problem.
Here you can a find a working example. By changing the FillDataXYZ values you can see how the Evaluate works in practice.

It looks like you have at least two choices here:
use some collection which stores value to handle
an approach inspired by Chain-of-responsibility pattern
Let's start from collection which stores value to handle
At first, we need our class with properties to be filled:
public class BigObject
{
public int A { get; set; }
public int B { get; set; }
public int C { get; set; }
}
Then this is our class which will handle all your properties:
public class BigObjectHandler
{
Dictionary<string, Action> _handlerByproperty = new ();
BigObject _bigObject;
public BigObjectHandler(BigObject bigObject)
{
_bigObject = bigObject;
_handlerByproperty.Add("A", GetDataA);
_handlerByproperty.Add("B", GetDataB);
_handlerByproperty.Add("C", GetDataC);
}
public void Handle(string propertyName) =>
_handlerByproperty[propertyName].Invoke();
private void GetDataA()
{
_bigObject.A = 1; // sourceServiceA.GetData();
}
private void GetDataB()
{
_bigObject.B = 1; // sourceServiceA.GetData();
}
private void GetDataC()
{
_bigObject.C = 1; // sourceServiceA.GetData();
}
}
And then you can call the above code like this:
IEnumerable<string> propertiesToFill = new List<string> { "A", "B" };
BigObject bigObject = new ();
BigObjectHandler bigObjectMapHandler = new (bigObject);
foreach (var propertyToFill in propertiesToFill)
{
bigObjectMapHandler.Handle(propertyToFill);
}
OUTPUT:
A = 1
B = 1
Chain-of-responsibility pattern
If you have many if else statements, then you can try to use "Chain-of-responsibility pattern". As wiki says:
the chain-of-responsibility pattern is a behavioral design pattern
consisting of a source of command objects and a series of processing
objects. Each processing object contains logic that defines the
types of command objects that it can handle; the rest are passed to
the next processing object in the chain. A mechanism also exists for
adding new processing objects to the end of this chain
However, we will not stop execution if some of condition is met. Let me show an example.
At first, we need some abstraction of handler:
public abstract class BigObjectHandler
{
private BigObjectHandler _nextBigObjectHandler;
public void SetSuccessor(BigObjectHandler bigObjectHandler)
{
_nextBigObjectHandler = bigObjectHandler;
}
public virtual BigObject Execute(BigObject bigObject,
BigObjectFilter parameter)
{
if (_nextBigObjectHandler != null)
return _nextBigObjectHandler.Execute(bigObject, parameter);
return bigObject;
}
}
Then we need concrete implemenatation of these handlers for your properties. This properties will be filled
by your sourceServiceX.GetData():
public class BigObjectAHandler : BigObjectHandler
{
public override BigObject Execute(BigObject bigObject, BigObjectFilter filter)
{
if (filter.FillA)
{
bigObject.A = 1; // sourceServiceA.GetData();
}
return base.Execute(bigObject, filter);
}
}
And:
public class BigObjectBHandler : BigObjectHandler
{
public override BigObject Execute(BigObject bigObject, BigObjectFilter filter)
{
if (filter.FillB)
{
bigObject.B = 2; // sourceServiceB.GetData();
}
return base.Execute(bigObject, filter);
}
}
And:
public class BigObjectCHandler : BigObjectHandler
{
public override BigObject Execute(BigObject bigObject, BigObjectFilter filter)
{
if (filter.FillC)
{
bigObject.C = 3; // sourceServiceC.GetData();
}
return base.Execute(bigObject, filter);
}
}
And these are object with data:
public class BigObject
{
public int A { get; set; }
public int B { get; set; }
public int C { get; set; }
}
And some filter which will contain settings of what property should be filled:
public class BigObjectFilter
{
public bool FillA { get; set; } = true;
public bool FillB { get; set; }
public bool FillC { get; set; }
}
And then we can call the above code like this:
BigObjectHandler chain = new BigObjectAHandler();
BigObjectHandler objectBHandler = new BigObjectBHandler();
BigObjectHandler objectCHandler = new BigObjectCHandler();
chain.SetSuccessor(objectBHandler);
objectBHandler.SetSuccessor(objectCHandler);
BigObjectFilter bigObjectFilter = new BigObjectFilter();
bigObjectFilter.FillA = true;
BigObject vehicle = chain.Execute(new BigObject(), bigObjectFilter); // A = 1
It can be seen after code execution that onle property A is handled. Output is:
A = 1
B = 1

Get data type from PropertyDeclarationSyntax

i am working on source generator and i need to read properties data type as string
Is there any solution to get data type name such as int, string, bool, etc...?
EDIT:
var typeName = property.Type.ToString(); throws exception
EDIT 2:
public void Execute(GeneratorExecutionContext context)
{
var model = new TemplateModel();
var syntaxReceiver = (SolnetParsableClassExplorer)context.SyntaxReceiver;
syntaxReceiver?.SolnetDtos.ForEach(dto =>
{
var typeNodeSymbol = context.Compilation
.GetSemanticModel(dto.SyntaxTree)
.GetDeclaredSymbol(dto);
var dataClass = new DataClassModel();
foreach (var member in dto.DescendantNodes())
{
if (member is PropertyDeclarationSyntax property)
{
dataClass.AddProperty(property);
}
}
dataClass.ClassName = dto.Identifier.ValueText;
model.DataClassModels.Add(dataClass);
});
...
}
internal class SolnetParsableClassExplorer : ISyntaxReceiver
{
public List<ClassDeclarationSyntax> SolnetDtos { get; } = new();
public void OnVisitSyntaxNode(SyntaxNode syntaxNode)
{
if (syntaxNode is ClassDeclarationSyntax classSyntax &&
classSyntax.HaveAttribute("SolnetDto"))
{
SolnetDtos.Add(classSyntax);
}
}
}
internal class DataClassModel
{
public List<DataField> Properties = new List<DataField>();
public string Namespace { get; set; }
public string ClassName { get; set; }
public int Size => Properties.Sum(p => p.Size);
public void AddProperty(PropertyDeclarationSyntax property)
{
// Here generator throw exception
var typeName = property.Type.ToString();
Properties.Add(
new DataField
{
PropertyName = property.Identifier.ValueText,
DataType = typeName,
Size = GetPropertySize(compilation, property, typeName),
WriteMethod = GetWriteMethod(typeName),
ReadMethod = GetReadMethod(typeName),
Offset = Size
});
}

I hope I understood your question correctly. To retrieve the string representation, you could use the TypeSyntax.ToString()
var strType = propertyDeclarationSyntax.Type.ToString();
For example, for the following
public string Bar1 { get; set; }
public int Bar2 { get; set; }
public long Bar3 { get; set; }
Result
Property Bar1 : string
Property Bar2 : int
Property Bar3 : long

Dynamic cast in c# in runtime

I have 2 classes as you can see :
static void Main(string[] args)
{
object m = (??????)"salam";
}
public class A
{
public string name { set; get; }
public static implicit operator A(string _name)
{
A aa = new A();
aa.name = _name;
return aa;
}
}
public class B
{
public string family { set; get; }
public static implicit operator B(string _family)
{
B bb = new B();
bb.family = _family;
return bb;
}
}
I need to cast my string in runtime in this line :
object m = (??????)"salam";
Is there any solution to pass my class name as a string to cast my value .for example in runtime I need to cast "salam" to A or maybe B
The static cast is working good like this
object m = (A)salam";
object m = (B)"salam";
But I need to cast my string in runtime
Type x=null;
If(condition)
x can be type of A
else
x can be type of B
object m = (x)"salam";

You need to use Interfaces for such a need. The following code shows how to do so.
To simulate your situtation, I wrote a method to return either A or B based on time.
Here the list contains a bunch of objects which may be of Type A or B, depending on the second of execution. In the real-world scenario, you would get your types in various other ways.
public class StackOverflowQuestion
{
public static void Run()
{
List<IBase> list = new List<IBase>();
string types = "";
for (int i = 0; i < 10; i++)
{
var randomType = GiveMeARandomIBaseType();
System.Threading.Thread.Sleep(750);
IBase hello = randomType.Convert("salam");
list.Add(hello);
types += hello.GetType().Name + ",";
}
types = types.Trim(',');
//sample result : B,B,A,B,A,A,B,A,B,B
}
static IBase GiveMeARandomIBaseType() {
if (DateTime.Now.Second % 2 == 0)
return new A();
else
return new B();
}
}
public interface IBase {
public IBase Convert(string s);
}
public static class MyExtensions {
public static T Convert<T>(this string str, IBase b) where T : IBase {
try
{
return (T)b.Convert(str);
}
catch (Exception)
{
return default;
}
}
}
public class A : IBase
{
public IBase Convert(string s) {
return (A)s;
}
public string name { set; get; }
public static implicit operator A(string _name)
{
A aa = new A();
aa.name = _name;
return aa;
}
}
public class B : IBase
{
public IBase Convert(string s)
{
return (B)s;
}
public string family { set; get; }
public static implicit operator B(string _family)
{
B bb = new B();
bb.family = _family;
return bb;
}
}

I had a similar problem and after all the study and time, I was able to approach the desired result in the following way.
I used an internal method to access (the inside of) the class and this method returns the cast desired result.
Step 1: in class
public class A
{
public string Name { set; get; }
public static implicit operator A(string name)
{
return new A
{
Name = name
};
}
public A GetCasting(object a)
{
A i = (A)a;
return i;
}
}
public class B
{
public string Family { set; get; }
public static implicit operator B(string family)
{
return new B
{
Family = family
};
}
public B GetCasting(object b)
{
B i = (B)b;
return i;
}
}
Step 2: in controller or code
var className = "A";
var classMethod = "GetCasting";
var classType = Assembly.GetExecutingAssembly().GetTypes().Where(t => t.IsClass && t.Name == className).FirstOrDefault();
var classInstance = Activator.CreateInstance(classType);
var castMethod = classType.GetMethod(classMethod);
var yourObject = "salam";
var objectData = new object[] { yourObject };
var resultObject = castMethod.Invoke(classInstance, objectData);

Mocking adding items to a list in .NET NMock2

I'm using NMock2 (2.1.3641.27570) in my unit tests.
IList<MyObj> values = _mock.NewMock<IList<MyObj>>();
That mock I return when my tested object calls the Values get property on my mocked object:
Expect.AtLeastOnce.On(_myKeepMock).GetProperty("Values").Will(Return.Value(values));
Then I expect value which is a MyObj to be added to my list values:
Expect.AtLeastOnce.On(values).Method("Add").With(value);
In order to avoid unexpected invocation of list'1.Add upon execution I understand I have to override the Equals method in the MyObj class:
public override bool Equals(object obj) { ...}
and compare by value instead of reference. But it doesn't even get called when executing the test (breakpoint not hit).
What do I need to do in order to pass the test when the item added to the list in the call is equal in value to the one added by the tested object?
I read about custom matchers but not sure if those apply here.
UPDATE
Full example:
using System.Collections.Generic;
using System.Linq;
using NMock2;
using NUnit.Framework;
public class Data
{
public int Val { get; set; }
public Data(int val) { Val = val; }
}
public class ModData
{
public int Val { get; set; }
protected bool Equals(ModData other)
{
return this.Val.Equals(other.Val);
}
public override int GetHashCode()
{
return this.Val.GetHashCode();
}
public override bool Equals(object obj)
{
ModData m = (ModData)obj;
return m != null && this.Val == m.Val;
}
}
public interface IAllData
{
IList<Data> Data { get; set; }
IList<ModData> ModData { get; set; }
}
public class AllData : IAllData
{
public IList<Data> Data { get; set; }
public IList<ModData> ModData { get; set; }
}
public class Calco
{
private IAllData _allData;
public Calco(IAllData allData)
{
_allData = allData;
}
public void Sum()
{
_allData.ModData.Add(new ModData { Val = _allData.Data.Sum(d => d.Val) });
}
}
public class CalcoTest
{
[Test]
public void Test()
{
Mockery mockery = new Mockery();
IList<Data> data = new List<Data>();
IList<ModData> modData = mockery.NewMock<IList<ModData>>();
IAllData allData = mockery.NewMock<IAllData>();
ModData modDatum = new ModData { Val = 4 };
data.Add(new Data(1));
data.Add(new Data(10));
Calco c = new Calco(allData);
Expect.AtLeastOnce.On(allData).GetProperty("Data").Will(Return.Value(data));
Expect.AtLeastOnce.On(allData).GetProperty("ModData").Will(Return.Value(modData));
Expect.AtLeastOnce.On(modData).Method("Add").With(modDatum);
c.Sum();
mockery.VerifyAllExpectationsHaveBeenMet();
}
}
Output:
NMock2.Internal.ExpectationException : unexpected invocation of list`1.Add(<WRM.Common.RiskCalculation.Tests.ModData>)
Expected:
at least 1 time: allData.Data, will return <System.Collections.Generic.List`1[WRM.Common.RiskCalculation.Tests.Data]> [called 1 time]
at least 1 time: allData.ModData, will return <list`1> [called 1 time]
at least 1 time: list`1.Add(equal to <WRM.Common.RiskCalculation.Tests.ModData>) [called 0 times]
Notice how it expects invocation of list'1.Add(<WRM.Common.RiskCalculation.Tests.ModData>)
and then shows it didn't call list'1.Add(<WRM.Common.RiskCalculation.Tests.ModData>)

Custom Matchers ARE the answer: http://nmock.sourceforge.net/advanced.html
public class IsMod
{
public static Matcher Equal(ModData otherMod)
{
return new ModMatcher(otherMod);
}
}
internal class ModMatcher : Matcher
{
private readonly ModData _mod;
public ModMatcher(ModData mod)
{
_mod = mod;
}
public override bool Matches(object o)
{
ModData m = (ModData)o;
return _mod.Val.Equals(m.Val);
}
public override void DescribeTo(TextWriter writer)
{
writer.Write("Value same ");
writer.Write(_mod.Val);
}
}
And then
Expect.AtLeastOnce.On(modData).Method("Add").With(IsMod.Equal(modDatum));
Done!

Invoke method similar to WCF invoker?

Some strong typed classes:
public class A
{
public C Process(B b)
{
return new C()
{
Output = b.Property + " bar!"
};
}
}
public class B
{
public string Property {get;set;}
}
public class C
{
public string Output {get;set;}
}
Input as JSON string:
string input = "{\"Property\":\"foo\"}";
And what I want is if I have instance of A as object, I want to invoke this JSON and retrieve object output:
object instanceOfA = new A();
object result = instanceOfA.GetType().GetMethod("Process").Invoke(instanceOfA, new []{ /*json here?*/});
So, it is basically similar to some JavaScript call on some plain argument.

What about changing the method signature for the 'Process' method to take a string as input instead and attempting to de-serialize the input to the type you want? So something like this:
string input = "{\"Property\":\"foo\"}";
object instanceOfA = new A();
object result = instanceOfA.GetType().GetMethod("Process").Invoke(instanceOfA, new object[]{ input });
public class A
{
public C Process(string input)
{
var b = (B) JsonConvert.DeserializeObject(input, typeof(B));
if (!string.IsNullOrEmpty(b.Property))
{
return new C()
{
Output = b.Property + " bar!"
};
}
return null;
}
}
public class B
{
public string Property { get; set; }
}
public class C
{
public string Output { get; set; }
}

Problem was simply solved with Newtonsoft.Json features:
public class JsonInvoker
{
private readonly MethodInfo _methodInfo;
private readonly Type _paramType;
private readonly JsonSerializerSettings _settings;
public JsonInvoker(Type instanceType, string methodName)
{
_methodInfo = instanceType.GetMethod(methodName);
_paramType = _methodInfo.GetParameters()[0].ParameterType;
_settings = new JsonSerializerSettings
{
ContractResolver = new RequireObjectPropertiesContractResolver(),
MissingMemberHandling = MissingMemberHandling.Error
};
}
public object Invoke(object instance, string json)
{
var input = JsonConvert.DeserializeObject(json, _paramType, _settings);
var output = _methodInfo.Invoke(instance, new[] { input });
return output;
}
private class RequireObjectPropertiesContractResolver : DefaultContractResolver
{
protected override JsonObjectContract CreateObjectContract(Type objectType)
{
var contract = base.CreateObjectContract(objectType);
contract.ItemRequired = Required.AllowNull;
return contract;
}
}
}
Now I can invoke my method:
class Program
{
static void Main(string[] args)
{
object plugin = new A();
string json = "{\"Property\":\"foo\"}";
var invoker = new JsonInvoker(plugin.GetType(), "Process");
//here I call invoker with simple string.
var output = invoker.Invoke(plugin, json);
}
}
public class A
{
public C Process(B input)
{
return new C
{
Property = input.Property + " bar"
};
}
}
public class C
{
public string Property { get; set; }
}
public class B
{
public string Property { get; set; }
}