Develop Reference

How to configure swashbuckle correct for polymorphism

I have a problem to get the right OpenApi definition aftr update from 5.0.0 to 5.4.1
We had custom Polymorphism filter with 5.0.0 version, but they does not work correct with latest one. So I removed them and started to use GeneratePolymorphicSchemas(). It does what I need for our polymorphic models but not just for them. We have also some other abstract and concrete classes, where we don't need type discriminator. I tried different configurations but without any success. Either the generated definition is wrong or I get error on swagger UI or a server 503 error.
Link to the sample project Sample project
Here are my polimorhic models
namespace SwashbuckleTest.Models
{
public interface ITypeDiscriminator
{
string TypeDiscriminator { get; }
}
public abstract class SurveyStep : ITypeDiscriminator
{
public virtual string Id { get; set; }
public string TypeDiscriminator => GetType().Name;
}
public abstract class SurveyStepResult : ITypeDiscriminator
{
public string Id { get; set; }
public string TypeDiscriminator => GetType().Name;
}
public class BoolStep : SurveyStep
{
private string _id;
public BoolStep()
{
ResultObject = new BoolStepResult();
}
public override string Id
{
get => _id;
set
{
_id = value;
ResultObject.Id = value;
}
}
public string Question { get; set; }
public BoolStepResult ResultObject { get; }
}
public class BoolStepResult : SurveyStepResult
{
public bool Value { get; set; }
}
}
Here other models
namespace SwashbuckleTest.Models
{
public abstract class SomeBaseModel
{
public string BaseValue { get; set; }
}
public class SomeConcreteModel : SomeBaseModel
{
public int ConcreteValue { get; set; }
}
}
and configurations I have tried
options.UseAllOfToExtendReferenceSchemas();
options.GeneratePolymorphicSchemas(t =>
{
var types = t.Is<SurveyStep>() ? new List<Type>() {typeof(BoolStep)}
: t.Is<SurveyStepResult>() ? new List<Type>() {typeof(BoolStepResult)}
: null;
return types;
} , t => t.Is<ITypeDiscriminator>() ? nameof(ITypeDiscriminator.TypeDiscriminator).ToCamelCase() : null);
// or
options.GeneratePolymorphicSchemas(discriminatorSelector: t => t.Is<ITypeDiscriminator>() ? nameof(ITypeDiscriminator.TypeDiscriminator).ToCamelCase() : null);

I found the problem by my self.
The Is<> extension method does not filter abstract classes so we got here endless recursion.
It helped us to generate swagger.json, but we got other problems, that are little bit deeper.

Get existing instance of List<T>

I've inherited a bloated project that uses a huge class as an in-memory database:
public class Database
{
public class Parameter1
{
public string Code { get; set; }
public string Label { get; set; }
public List<Parameter1Value> paramValues;
}
public class Parameter2
{
public string Code { get; set; }
public string Label { get; set; }
public List<Parameter2Value> paramValues;
}
public class Parameter1Value
{
public string Value { get; set;}
public Parameter parameter { get; set;}
}
public class Parameter2Value
{
public int Value { get; set;}
public Parameter2 parameter { get; set;}
}
public List<Parameter1> parameter1List { get; set; }
public List<Parameter2> parameter2List { get; set; }
}
I am creating a generic method that creates instances of Parameter1 or Parameter2 (see below) and should add those to their respective lists, but I don't know how to use those types to get the parameter1List or parameter2List instances from my Database class. The Database class holds only one List<T> property for each defined type. Is this possible?
This is the generic method used to create instances:
public static Database Add<T>(this Database database, string code, string label) where T : new()
{
T itemToCreate = (T)Activator.CreateInstance(typeof(T));
itemToCreate.Code = code;
itemToCreate.Label = label;
var listForItem = database.GetList<T>; // This is the missing functionality
listForItem.Add(itemToCreate);
return database;
}

Here is a solution using interfaces and generic constraints.
Create an interface to represent a generic parameter class and add members to the interface as required:
public interface IParameter { ... }
And an interface to represent a list of parameters:
public interface IParameterList<TParameter> where TParameter : IParameter
{
List<TParameter> ParameterList { get; set; }
}
Have the Database and Parameter classes implement these new interfaces:
public class Parameter1 : IParameter
public class Parameter2 : IParameter
public class Database : IParameterList<Parameter1>, IParameterList<Parameter2>
{
List<Parameter1> IParameterList<Parameter1>.ParameterList { get => parameter1List; set => parameter1List = value; }
List<Parameter2> IParameterList<Parameter2>.ParameterList { get => parameter2List; set => parameter2List = value; }
...
}
Add a where TParameter : IParameter constraint to your generic Parameter factory function, and have the factory function require an argument of type IParameterList<TParameter> which is an instance of the Database class. This satisfies the compiler that the Database class owns a list of TParameter. Now we just do db.ParameterList.Add(r) to add our new parameter to the correct list.
public static TParameter CreateParameter<TParameter>(IParameterList<TParameter> db) where TParameter : IParameter, new()
{
var r = new TParameter(); // This is the generic function you mentioned. Do stuff here to create your Parameter class.
db.ParameterList.Add(r); // Add the newly created parameter to the correct list
return r;
}
Code dump (full working version after I picked up your edit which added the generic factory function):
public class Parameter1 : IParameter
{
public string Code { get; set; }
public string Label { get; set; }
public List<Parameter1Value> paramValues;
}
public class Parameter2 : IParameter
{
public string Code { get; set; }
public string Label { get; set; }
public List<Parameter2Value> paramValues;
}
public class Parameter1Value
{
public string Value { get; set; }
public Parameter parameter { get; set; }
}
public class Parameter2Value
{
public int Value { get; set; }
public Parameter2 parameter { get; set; }
}
public class Database : IParameterList<Parameter1>, IParameterList<Parameter2>
{
// Note: Setters for the List properties probably not needed here or in IParameterList as with the following code we instantiate them at class construction time and, in this MCVE at least, there are no further assignments
public List<Parameter1> parameter1List { get; set; } = new List<Parameter1>();
public List<Parameter2> parameter2List { get; set; } = new List<Parameter2>();
List<Parameter1> IParameterList<Parameter1>.ParameterList { get => parameter1List; set => parameter1List = value; }
List<Parameter2> IParameterList<Parameter2>.ParameterList { get => parameter2List; set => parameter2List = value; }
public static TParameter Add<TParameter>(IParameterList<TParameter> db, string code, string label) where TParameter : IParameter, new()
{
var itemToCreate = new TParameter();
itemToCreate.Code = code;
itemToCreate.Label = label;
db.ParameterList.Add(itemToCreate); // Add the newly created parameter to the correct list
return itemToCreate;
}
}
public interface IParameter
{
string Code { get; set; }
string Label { get; set; }
}
public interface IParameterList<TParameter> where TParameter : IParameter
{
List<TParameter> ParameterList { get; set; }
}
// Testing:
void Main()
{
var db = new Database();
Database.Add<Parameter1>(db, "hello", "hello2");
Database.Add<Parameter1>(db, "hello", "hello2");
Database.Add<Parameter2>(db, "hello", "hello2");
Console.WriteLine($"P1 count (should be 2): {db.parameter1List.Count()}; P2 count (should be 1): {db.parameter2List.Count}");
}
Output:
P1 count (should be 2): 2; P2 count (should be 1): 1

Here is a solution which acquires the target list using generics and reflection:
public static List<T> GetList<T>(this Database dataBase) where T : new()
{
return dataBase.GetType()
.GetProperties()
.Where(x => x.PropertyType == typeof(List<T>))
.Select(x => (List<T>)x.GetValue(dataBase))
.FirstOrDefault();
}
Credit: Michael Randall in the comments

Pass Class Property as Generic Type

I am attempting to implement a base class for FluentValidation that will quickly build a validator for classes. My base class functions attempt to take a class's property as a Generic type argument in order to apply rules. But as you'll see in the code its not quite syntactically (among other things) correct.
It probably much easier to explain in code:
public class BaseValidator<T> : AbstractValidator<T>
{
public void ruleForText<U>(string msg)
{
RuleFor(obj => obj.U).NotEmpty().WithMessage(msg);
RuleFor(obj => obj.U).Length(1, 100).WithMessage(msg);
RuleFor(obj => obj.U).Matches("[A-Z]*").WithMessage(msg);
}
public void ruleForEmail<U>(string msg)
{
RuleFor(obj => obj.U).NotEmpty().WithMessage(msg);
RuleFor(obj => obj.U).EmailAddress().WithMessage(msg);
}
}
public class Member {
public string Name { get; set; }
public string Email { get; set; }
}
public class Post{
public string Title { get; set; }
}
public class MemberValidator :BaseValidator<Member>
{
public MemberValidator()
{
// Not valid syntax to pass name or even Member.Name
// How can I pass Member.Name as the generic type?
ruleForText<Name>();
ruleForEmail<Email>();
}
}
public class PostValidator :BaseValidator<Post>
{
public MemberValidator()
{
ruleForText<Title>();
}
}

This might be what you are looking for. You need to pass in an expression with the function parameter being a string.
public class BaseValidator<T> : AbstractValidator<T>
{
public void RuleForText(Expression<Func<T, string>> expression, string msg)
{
RuleFor(expression).NotEmpty().WithMessage(msg);
RuleFor(expression).Length(1, 100).WithMessage(msg);
RuleFor(expression).Matches("[A-Z]*").WithMessage(msg);
}
public void RuleForEmail(Expression<Func<T, string>> expression, string msg)
{
RuleFor(expression).NotEmpty().WithMessage(msg);
RuleFor(expression).EmailAddress().WithMessage(msg);
}
}
public class MemberValidator : BaseValidator<Member>
{
public MemberValidator()
{
RuleForText(member => member.Name, "My Message");
RuleForEmail(member => member.Email, "My Message");
}
}
public class Member
{
public string Name { get; set; }
public string Email { get; set; }
}

How to use the same foreach code for 2 collections?

I have 2 collections of 2 different types but have almost the same set of fields.
in one function, I need to iterate through one of the collections depending on one condition.
I want to write only one code block that will cover both cases.
Example:
I have the following code:
if (condition1)
{
foreach(var type1var in Type1Collection)
{
// Do some code here
type1var.Notes = "note";
type1var.Price = 1;
}
}
else
{
foreach(var type2var in Type2Collection)
{
// the same code logic is used here
type2var.Notes = "note";
type2var.Price = 1;
}
}
Now: I want to simplify this code to use the same logic only once ( as they are identical ), something like the following ( P.S : I know the following code is not correct, I am just explaining what I want to do ):
var typecollection = Condition1 ? Type1Collection : Type2Collection;
foreach(var typevar in TypeCollection)
{
// the same code logic is used here
typevar.Notes = "note";
typevar.Price = 1;
}
The definition of Type1 & Type2 is similar to the following code ( Actually they are Entity objects):
public class Type1 : EntityObject
{
public int Type1ID { get; set; }
public int Type1MasterID { get; set; }
public String Notes { get; set; }
public decimal Price { get; set; }
}
public class Type2 : EntityObject
{
public int Type2ID { get; set; }
public int Type2MasterID { get; set; }
public String Notes { get; set; }
public decimal Price { get; set; }
}
Update 1:
I have included some sample code I am using inside foreach block ( I am accessing a public properties of the 2 types).
Update 2:
I have included sample Type1 & Type2 definitions, as you can see I have 2 common Public Properties in both classes which I want to update in foreach block.
Update 3:
I am sorry for the confusion, Type1 & Type2 are derived from EntityObject ( They are both part of my entity model, and the Type1Collection & Type2Collection are actually EntityCollection of these 2 entities.

You could use dynamic. Note you will lose type safety.
var list1 = new List<bool>(){true,false};
var list2 = new List<int>(){1,2};
var typecollection = condition1 ? list1.Cast<dynamic>() : list2.Cast<dynamic>();
foreach (var value in typecollection)
{
//then you can call a method you know they both have
Debug.WriteLine(value.ToString());
}
Or if they share a common interface you can cast directly to that. You will maintain type safety
var list1 = new List<bool>(){true,false};
var list2 = new List<int>(){1,2};
var typecollection = condition1 ? list1.Cast<IConvertible>() : list2.Cast<IConvertible>();
foreach (IConvertible convertible in typecollection)
{
//we now know they have a common interface so we can call a common method
Debug.WriteLine(convertible.ToString());
}

Given Jon Skeet's hint of using LINQ's Concat method and the OP's statement that the classes involved are EntityObjects, here's another possible solution. This assumes that the EntityObject subclasses are defined as partial classes:
public partial class Type1 : EntityObject
{
public int Type1ID { get; set; }
public int Type1MasterID { get; set; }
public String Notes { get; set; }
public decimal Price { get; set; }
}
public partial class Type2 : EntityObject
{
public int Type2ID { get; set; }
public int Type2MasterID { get; set; }
public String Notes { get; set; }
public decimal Price { get; set; }
}
This allows the OP to declare an interface with the common properties, and have his EntityObject subclasses implement that interface:
public interface IMyType
{
String Notes { get; set; }
decimal Price { get; set; }
}
public partial class Type1 : IMyType {}
public partial class Type2 : IMyType {}
And the original code becomes:
var query = (
from type1var in type1Collection
where condition1
select (IMyType)type1var
).Concat(
from type2var in type2Collection
where !condition1
select (IMyType)type2var
);
foreach(var myType in query)
{
myType.Notes = "note";
myType.Price = 1;
}

You could create a base type for type1 and type2 that groups the common properties between the two classes:
class MyBaseType {
// Common properties
}
class Type1 : MyBaseType {
// Specific properties
}
class Type2 : MyBaseType {
// Specific properties
}
Then, you could do something like this:
IEnumerable<MyBaseType> collection;
if(condition1)
collection = type1Collection;
else
collection = type2Collection;
foreach(MyBaseType element in collection) {
// Common logic
}
EDIT:
As Simon points out in the comments, you should use an interface instead of a base type if it's enough (i.e you don't need a specific implementation for both types).

This is not a very nice way to do it, but it would atleast work.
var type1Collection = new Collection<Type1>();
var type2Collection = new Collection<Type2>();
var condition1 = new Random().Next(0, 2) != 0;
dynamic selectedCollection;
if (condition1)
selectedCollection = type1Collection;
else
selectedCollection = type2Collection;
foreach (var typeVar in selectedCollection)
{
typeVar.Notes = "note";
typeVar.Price = 1;
}

I'm surprised nobody else has suggested an extension method yet:
public interface IMyType
{
String Notes { get; set; }
decimal Price { get; set; }
}
public static class MyTypeExtensions
{
public static void MyLogic(this IMyType myType)
{
// whatever other logic is needed
myType.Notes = "notes";
myType.Price = 1;
}
}
Now, your original types just need to implement IMyType:
public class Type1 : IMyType
{
public int Type1ID { get; set; }
public int Type1MasterID { get; set; }
public String Notes { get; set; }
public decimal Price { get; set; }
}
public class Type2 : IMyType
{
public int Type2ID { get; set; }
public int Type2MasterID { get; set; }
public String Notes { get; set; }
public decimal Price { get; set; }
}
Then the original code becomes:
if (condition1)
{
foreach (var type1 in type1Collection)
{
type1.MyLogic();
}
}
else
{
foreach (var type2 in type2Collection)
{
type2.MyLogic();
}
}

You can do it with Predicate and Action stored in a Dictionary. I am suggesting Action here since the code snippet doesn't seems to return anything
public class IterationExample
{
private readonly Dictionary<bool, Action> dictionary;
public IterationExample()
{
dictionary = new Dictionary<bool, Action> { { true, CollectionOneIterator }, { false, CollectionTwoIterator } };
}
public void PublicMethod()
{
dictionary[condition]();
}
private void CollectionOneIterator()
{
foreach (var loopVariable in Type1Collection)
{
//Your code here
}
}
private void CollectionTwoIterator()
{
foreach (var loopVariable in Type2Collection)
{
//Your code here
}
}
}
With this way the readbility and testability of your code improves and also avoids long methods.
Edit:
public class Entity
{
public IList<string> Type1Collection { get; set; }
public IList<string> Type2Collection { get; set; }
}
public class ConsumingClass
{
public void Example()
{
var entity = new Entity();
entity.PublicMethod();
}
}
public static class IterationExample
{
private static readonly Dictionary<bool, Action<Entity>> dictionary;
static IterationExample()
{
dictionary = new Dictionary<bool, Action<Entity>> { { true, CollectionOneIterator }, { false, CollectionTwoIterator } };
}
public static void PublicMethod(this Entity entity)
{
dictionary[condition]();
}
private static void CollectionOneIterator(Entity entity)
{
foreach (var loopVariable in entity.Type1Collection)
{
//Your code here
}
}
private static void CollectionTwoIterator(Entity entity)
{
foreach (var loopVariable in entity.Type2Collection)
{
//Your code here
}
}
}

C# - copying property values from one instance to another, different classes

I have two C# classes that have many of the same properties (by name and type). I want to be able to copy all non-null values from an instance of Defect into an instance of DefectViewModel. I was hoping to do it with reflection, using GetType().GetProperties(). I tried the following:
var defect = new Defect();
var defectViewModel = new DefectViewModel();
PropertyInfo[] defectProperties = defect.GetType().GetProperties();
IEnumerable<string> viewModelPropertyNames =
defectViewModel.GetType().GetProperties().Select(property => property.Name);
IEnumerable<PropertyInfo> propertiesToCopy =
defectProperties.Where(defectProperty =>
viewModelPropertyNames.Contains(defectProperty.Name)
);
foreach (PropertyInfo defectProperty in propertiesToCopy)
{
var defectValue = defectProperty.GetValue(defect, null) as string;
if (null == defectValue)
{
continue;
}
// "System.Reflection.TargetException: Object does not match target type":
defectProperty.SetValue(viewModel, defectValue, null);
}
What would be the best way to do this? Should I maintain separate lists of Defect properties and DefectViewModel properties so that I can do viewModelProperty.SetValue(viewModel, defectValue, null)?
Edit: thanks to both Jordão's and Dave's answers, I chose AutoMapper. DefectViewModel is in a WPF application, so I added the following App constructor:
public App()
{
Mapper.CreateMap<Defect, DefectViewModel>()
.ForMember("PropertyOnlyInViewModel", options => options.Ignore())
.ForMember("AnotherPropertyOnlyInViewModel", options => options.Ignore())
.ForAllMembers(memberConfigExpr =>
memberConfigExpr.Condition(resContext =>
resContext.SourceType.Equals(typeof(string)) &&
!resContext.IsSourceValueNull
)
);
}
Then, instead of all that PropertyInfo business, I just have the following line:
var defect = new Defect();
var defectViewModel = new DefectViewModel();
Mapper.Map<Defect, DefectViewModel>(defect, defectViewModel);

Take a look at AutoMapper.

There are frameworks for this, the one I know of is Automapper:
http://automapper.codeplex.com/
http://www.lostechies.com/blogs/jimmy_bogard/archive/2009/01/22/automapper-the-object-object-mapper.aspx

Replace your erroneous line with this:
PropertyInfo targetProperty = defectViewModel.GetType().GetProperty(defectProperty.Name);
targetProperty.SetValue(viewModel, defectValue, null);
Your posted code is attempting to set a Defect-tied property on a DefectViewModel object.

In terms of organizing the code, if you don't want an external library like AutoMapper, you can use a mixin-like scheme to separate the code out like this:
class Program {
static void Main(string[] args) {
var d = new Defect() { Category = "bug", Status = "open" };
var m = new DefectViewModel();
m.CopyPropertiesFrom(d);
Console.WriteLine("{0}, {1}", m.Category, m.Status);
}
}
// compositions
class Defect : MPropertyGettable {
public string Category { get; set; }
public string Status { get; set; }
// ...
}
class DefectViewModel : MPropertySettable {
public string Category { get; set; }
public string Status { get; set; }
// ...
}
// quasi-mixins
public interface MPropertyEnumerable { }
public static class PropertyEnumerable {
public static IEnumerable<string> GetProperties(this MPropertyEnumerable self) {
return self.GetType().GetProperties().Select(property => property.Name);
}
}
public interface MPropertyGettable : MPropertyEnumerable { }
public static class PropertyGettable {
public static object GetValue(this MPropertyGettable self, string name) {
return self.GetType().GetProperty(name).GetValue(self, null);
}
}
public interface MPropertySettable : MPropertyEnumerable { }
public static class PropertySettable {
public static void SetValue<T>(this MPropertySettable self, string name, T value) {
self.GetType().GetProperty(name).SetValue(self, value, null);
}
public static void CopyPropertiesFrom(this MPropertySettable self, MPropertyGettable other) {
self.GetProperties().Intersect(other.GetProperties()).ToList().ForEach(
property => self.SetValue(property, other.GetValue(property)));
}
}
This way, all the code to achieve the property-copying is separate from the classes that use it. You just need to reference the mixins in their interface list.
Note that this is not as robust or flexible as AutoMapper, because you might want to copy properties with different names or just some sub-set of the properties. Or it might downright fail if the properties don't provide the necessary getters or setters or their types differ. But, it still might be enough for your purposes.

This is cheap and easy. It makes use of System.Web.Script.Serialization and some extention methods for ease of use:
public static class JSONExts
{
public static string ToJSON(this object o)
{
var oSerializer = new System.Web.Script.Serialization.JavaScriptSerializer();
return oSerializer.Serialize(o);
}
public static List<T> FromJSONToListOf<T>(this string jsonString)
{
var oSerializer = new System.Web.Script.Serialization.JavaScriptSerializer();
return oSerializer.Deserialize<List<T>>(jsonString);
}
public static T FromJSONTo<T>(this string jsonString)
{
var oSerializer = new System.Web.Script.Serialization.JavaScriptSerializer();
return oSerializer.Deserialize<T>(jsonString);
}
public static T1 ConvertViaJSON<T1>(this object o)
{
return o.ToJSON().FromJSONTo<T1>();
}
}
Here's some similiar but different classes:
public class Member
{
public string Name { get; set; }
public int Age { get; set; }
public bool IsCitizen { get; set; }
public DateTime? Birthday { get; set; }
public string PetName { get; set; }
public int PetAge { get; set; }
public bool IsUgly { get; set; }
}
public class MemberV2
{
public string Name { get; set; }
public int Age { get; set; }
public bool IsCitizen { get; set; }
public DateTime? Birthday { get; set; }
public string ChildName { get; set; }
public int ChildAge { get; set; }
public bool IsCute { get; set; }
}
And here's the methods in action:
var memberClass1Obj = new Member {
Name = "Steve Smith",
Age = 25,
IsCitizen = true,
Birthday = DateTime.Now.AddYears(-30),
PetName = "Rosco",
PetAge = 4,
IsUgly = true,
};
string br = "<br /><br />";
Response.Write(memberClass1Obj.ToJSON() + br); // just to show the JSON
var memberClass2Obj = memberClass1Obj.ConvertViaJSON<MemberV2>();
Response.Write(memberClass2Obj.ToJSON()); // valid fields are filled

For one thing I would not place that code (somewhere) external but in the constructor of the ViewModel:
class DefectViewModel
{
public DefectViewModel(Defect source) { ... }
}
And if this is the only class (or one of a few) I would not automate it further but write out the property assignments. Automating it looks nice but there may be more exceptions and special cases than you expect.

Any chance you could have both classes implement an interface that defines the shared properties?