I have this entity:
public int Id { get; private set; }
public string Name { get; private set; }
public Behavior Behavior { get; private set; }
public Product(int id, string name, Behavior behavior)
{
Id = id;
Name = name;
Behavior = behavior;
}
In startup method I'm registering the EdmModel :
var builder = new ODataConventionModelBuilder();
var entitySet = builder.EntitySet<Product>("Products");
entitySet.EntityType.HasKey(x => x.Id);
var model = builder.GetEdmModel();
app.UseMvc(route =>
{
route.Select().Filter().Expand().OrderBy().Count().MaxTop(null);
route.MapODataServiceRoute("odata", null, model);
route.EnableDependencyInjection();
}
);
When I'm running my app, this exception occurs:
InvalidOperationException: The entity 'Product' does not have a key
defined.
If I change private setter to public all is working. Also others properties with private setters are giving: ODataException Product does not contain property with name 'Name'. How can I solve it ?
the question is quite old, I stumbled across the same issue now. Scalar properties (i.e. int, string, bool) with private setters are not recognized by the ODataConventionModelBuilder, even though it recognizes collections with private setters.
I could solve the problem using EntityTypeConfiguration<T> obtained via the model builder:
public class Article
{
public string ArticleNr { get; private set; }
public string SomeProperty { get; private set; }
}
var builder = new ODataConventionModelBuilder();
var articleBuilder = builder.EntityType<Article>();
articleBuilder.HasKey(a => a.ArticleNr);
articleBuilder.Property(a => a.SomeProperty);
builder.EntitySet<Article>("Articles");
var model = builder.GetEdmModel();
This is giving me a model that can be built, it recognizes the key in spite of its private setter and I can also issue queries against SomeProperty. But this way every property must be registered explicitly using a call to Property which seems very error prone when adding new properties. I think it should be able to write a custom convention for it, but I have not tried this so far.
Related
With a simple class/interface like this
public interface IThing
{
string Name { get; set; }
}
public class Thing : IThing
{
public int Id { get; set; }
public string Name { get; set; }
}
How can I get the JSON string with only the "Name" property (only the properties of the underlying interface) ?
Actually, when i make that :
var serialized = JsonConvert.SerializeObject((IThing)theObjToSerialize, Formatting.Indented);
Console.WriteLine(serialized);
I get the full object as JSON (Id + Name);
The method I use,
public class InterfaceContractResolver : DefaultContractResolver
{
private readonly Type _InterfaceType;
public InterfaceContractResolver (Type InterfaceType)
{
_InterfaceType = InterfaceType;
}
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
//IList<JsonProperty> properties = base.CreateProperties(type, memberSerialization);
IList<JsonProperty> properties = base.CreateProperties(_InterfaceType, memberSerialization);
return properties;
}
}
// To serialize do this:
var settings = new JsonSerializerSettings() {
ContractResolver = new InterfaceContractResolver (typeof(IThing))
};
string json = JsonConvert.SerializeObject(theObjToSerialize, settings);
Improved version with nested interfaces + support for xsd.exe objects
Yet another variation here. The code came from http://www.tomdupont.net/2015/09/how-to-only-serialize-interface.html with the following improvements over other answers here
Handles hierarchy, so if you have an Interface2[] within an Interface1 then it will get serialized.
I was trying to serialize a WCF proxy object and the resultant JSON came up as {}. Turned out all properties were set to Ignore=true so I had to add a loop to set them all to not being ignored.
public class InterfaceContractResolver : DefaultContractResolver
{
private readonly Type[] _interfaceTypes;
private readonly ConcurrentDictionary<Type, Type> _typeToSerializeMap;
public InterfaceContractResolver(params Type[] interfaceTypes)
{
_interfaceTypes = interfaceTypes;
_typeToSerializeMap = new ConcurrentDictionary<Type, Type>();
}
protected override IList<JsonProperty> CreateProperties(
Type type,
MemberSerialization memberSerialization)
{
var typeToSerialize = _typeToSerializeMap.GetOrAdd(
type,
t => _interfaceTypes.FirstOrDefault(
it => it.IsAssignableFrom(t)) ?? t);
var props = base.CreateProperties(typeToSerialize, memberSerialization);
// mark all props as not ignored
foreach (var prop in props)
{
prop.Ignored = false;
}
return props;
}
}
Inspired by #user3161686, here's a small modification to InterfaceContractResolver:
public class InterfaceContractResolver<TInterface> : DefaultContractResolver where TInterface : class
{
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
IList<JsonProperty> properties = base.CreateProperties(typeof(TInterface), memberSerialization);
return properties;
}
}
You can use conditional serialization. Take a look at this link. Basicly, you need to implement the IContractResolver interface, overload the ShouldSerialize method and pass your resolver to the constructor of the Json Serializer.
An alternative to [JsonIgnore] are the [DataContract] and [DataMember] attributes. If you class is tagged with [DataContract] the serializer will only process properties tagged with the [DataMember] attribute (JsonIgnore is an "opt-out" model while DataContract is "op-in").
[DataContract]
public class Thing : IThing
{
[DataMember]
public int Id { get; set; }
public string Name { get; set; }
}
The limitation of both approaches is that they must be implemented in the class, you cannot add them to the interface definition.
You can add the [JsonIgnore] annotation to ignore an attribute.
I'd like to share what we ended up doing when confronted with this task. Given the OP's interface and class...
public interface IThing
{
string Name { get; set; }
}
public class Thing : IThing
{
public int Id { get; set; }
public string Name { get; set; }
}
...we created a class that is the direct implementation of the interface...
public class DirectThing : IThing
{
public string Name { get; set; }
}
Then simply serialized our Thing instance, deserialized it as a DirectThing, then Serialized it as a DirectThing:
var thing = new Thing();
JsonConvert.SerializeObject(
JsonConvert.DeserializeObject<DirectThing>(JsonConvert.SerializeObject(thing)));
This approach can work with a long interface inheritance chain...you just need to make a direct class (DirectThing in this example) at the level of interest. No need to worry about reflection or attributes.
From a maintenance perspective, the DirectThing class is easy to maintain if you add members to IThing because the compiler will give errors if you haven't also put them in DirectThing. However, if you remove a member X from IThing and put it in Thing instead, then you'll have to remember to remove it from DirectThing or else X would be in the end result.
From a performance perspective there are three (de)serialization operations happening here instead of one, so depending on your situation you might like to evaluate the performance difference of reflector/attribute-based solutions versus this solution. In my case I was just doing this on a small scale, so I wasn't concerned about potential losses of some micro/milliseconds.
Hope that helps someone!
in addition to the answer given by #monrow you can use the default [DataContract] and [DataMember]
have a look at this
http://james.newtonking.com/archive/2009/10/23/efficient-json-with-json-net-reducing-serialized-json-size.aspx
Finally I got when it will not work...
If you want to have inside another complex object it will not be properly serialized.
So I have made version which will extract only data stored in specific assembly and for types which have the same base interface.
So it is made as .Net Core JsonContractResolver.
In addition to data extraction it solves:
a) camelCase conversion before sending data to client
b) uses top most interface from allowed scope (by assembly)
c) fixes order of fields: field from most base class will be listed first and nested object will meet this rule as well.
public class OutputJsonResolver : DefaultContractResolver
{
#region Static Members
private static readonly object syncTargets = new object();
private static readonly Dictionary<Type, IList<JsonProperty>> Targets = new Dictionary<Type, IList<JsonProperty>>();
private static readonly Assembly CommonAssembly = typeof(ICommon).Assembly;
#endregion
#region Override Members
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
if (type.Assembly != OutputJsonResolver.CommonAssembly)
return base.CreateProperties(type, memberSerialization);
IList<JsonProperty> properties;
if (OutputJsonResolver.Targets.TryGetValue(type, out properties) == false)
{
lock (OutputJsonResolver.syncTargets)
{
if (OutputJsonResolver.Targets.ContainsKey(type) == false)
{
properties = this.CreateCustomProperties(type, memberSerialization);
OutputJsonResolver.Targets[type] = properties;
}
}
}
return properties;
}
protected override string ResolvePropertyName(string propertyName)
{
return propertyName.ToCase(Casing.Camel);
}
#endregion
#region Assistants
private IList<JsonProperty> CreateCustomProperties(Type type, MemberSerialization memberSerialization)
{
// Hierarchy
IReadOnlyList<Type> types = this.GetTypes(type);
// Head
Type head = types.OrderByDescending(item => item.GetInterfaces().Length).FirstOrDefault();
// Sources
IList<JsonProperty> sources = base.CreateProperties(head, memberSerialization);
// Targets
IList<JsonProperty> targets = new List<JsonProperty>(sources.Count);
// Repository
IReadOnlyDistribution<Type, JsonProperty> repository = sources.ToDistribution(item => item.DeclaringType);
foreach (Type current in types.Reverse())
{
IReadOnlyPage<JsonProperty> page;
if (repository.TryGetValue(current, out page) == true)
targets.AddRange(page);
}
return targets;
}
private IReadOnlyList<Type> GetTypes(Type type)
{
List<Type> types = new List<Type>();
if (type.IsInterface == true)
types.Add(type);
types.AddRange(type.GetInterfaces());
return types;
}
#endregion
}
I have this API
public ActionResult AddDocument([FromBody]AddDocumentRequestModel documentRequestModel)
{
AddDocumentStatus documentState = _documentService.AddDocument(documentRequestModel, DocumentType.OutgoingPosShipment);
if (documentState.IsSuccess)
return Ok();
return BadRequest();
}
And this is my request model
public class AddDocumentRequestModel
{
public AddDocumentRequestModel(int partnerId, List<ProductRequestModel> products)
{
PartnerId = partnerId;
Products = products;
}
[Range(1, int.MaxValue, ErrorMessage = "Value for {0} must be between {1} and {2}.")]
public int PartnerId { get; private set; }
[Required, MustHaveOneElement(ErrorMessage = "At least one product is required")]
public List<ProductRequestModel> Products { get; private set; }
}
so when I'm trying to hit the API with this body
{
"partnerId": 101,
"products": [{
"productId": 100,
"unitOfMeasureId": 102,
"quantity":5
}
]
}
this is the request : System.NotSupportedException: Deserialization of reference types without parameterless constructor is not supported. Type 'Alati.Commerce.Sync.Api.Controllers.AddDocumentRequestModel'
I don't need parameterless constructor,because it doesn't read the body parameters.Is there any other way for deserialization?
You can achieve your desired result. You need to switch to NewtonsoftJson serialization (from package Microsoft.AspNetCore.Mvc.NewtonsoftJson)
Call this in Startup.cs in the ConfigureServices method:
services.AddControllers().AddNewtonsoftJson();
After this, your constructor will be called by deserialization.
Extra info: I am using ASP Net Core 3.1
Later Edit: I wanted to give more info on this, as it seems that this can also be achieved by using System.Text.Json, although custom implementation is necessary. The answer from jawa states that Deserializing to immutable classes and structs can be achieved with System.Text.Json, by creating a custom converter (inherit from JsonConverter) and registering it to the converters collection (JsonSerializerOptions.Converters) like so:
public class ImmutablePointConverter : JsonConverter<ImmutablePoint>
{
...
}
and then...
var serializeOptions = new JsonSerializerOptions();
serializeOptions.Converters.Add(new ImmutablePointConverter());
serializeOptions.WriteIndented = true;
Just in case someone have the same issue I had, I was using abstract class, once removed the abstract key word, it all worked just fine.
Just Add [JsonConstructor] before your constructor
like this
public class Person
{
public string Name { get; set; }
public int LuckyNumber { get; private set; }
[JsonConstructor]
public Person(int luckyNumber)
{
LuckyNumber = luckyNumber;
}
public Person() { }
}
There are still some limitations using System.Text.Json - have a look here: https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-migrate-from-newtonsoft-how-to#table-of-differences-between-newtonsoftjson-and-systemtextjson
Deserialization without parameterless constructor using a parameterized constructor is not supported yet (but it's on their plan). You can implement your custom JsonConverter (like in this example: https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-migrate-from-newtonsoft-how-to#deserialize-to-immutable-classes-and-structs) or - like Adrian Nasul above suggested: use Newtonsoft.Json and then you can use the [JsonConstructor] attribute
In my case I had set a class as internal and when I made it public it worked. The error message was really of little help with this specific circumstance.
Old (actual class name changed to ClassName in the example
internal class Rootobject
{
[JsonConstructor]
public Rootobject(ClassName className)
{
ClassName = className?? throw new ArgumentNullException(nameof(className));
}
public ClassName ClassName { get; set; }
}
New:
public class Rootobject
{
[JsonConstructor]
public Rootobject(ClassName className)
{
ClassName = branding ?? throw new ArgumentNullException(nameof(className));
}
public ClassName ClassName { get; set; }
}
In my case error, caused was inside InnerException. There is my class had a field with a custom class type that did not have a parameterless constructor. I've added a parameterless constructor to the inner class and the problem has gone away.
I do a Generic and using DI
so I create a empty class
public class DBRepo
{
}
and my model class to inheriting class DBRepo
public partial class UserAccount : DBRepo
{
public int Id { get; set; }
public string Account { get; set; }
public string Pwd { get; set; }
}
then this is a Interface to do CRUD
public interface IDBAction<TEntity> where TEntity : class,new()
{
void UpdateData(TEntity _entity);
void GetAllData(TEntity _entity);
}
public class DBService<TEntity> : IDBAction<TEntity> where TEntity : class,new()
{
private readonly CoreContext _db;
public DBService(CoreContext _db)
{
this._db = _db;
}
public void UpdateData(TEntity _entity)
{
this._db.Set<TEntity>().UpdateRange(_entity);
this._db.SaveChanges();
}
public void GetAllData(TEntity _entity)
{
var x = this._db.Set<TEntity>().Select(o => o).ToList();
}
}
And I Dependency Injection Service Provider in constructor
this.DBProvider = new ServiceCollection()
.AddScoped<IDBAction<DBRepo>, DBService<DBRepo>>()
.AddScoped<DBContext>()
.AddDbContext<CoreContext>(options => options.UseSqlServer(ConnectionString))
.BuildServiceProvider();
last step I Get Services
DBProvider.GetService<IDBAction<DBRepo>>().GetAllData(new UserAccount());
I will get a error message same with title
or I change to
DBProvider.GetService<IDBAction<UserAccount>>().GetAllData(new UserAccount());
I'll get other message
Object reference not set to an instance of an object.'
but the void UpdateData() is can work,
so how to fix GetAllData() problem?
The error simply is because the class you're using here UserAccount has apparently not been added to your context, CoreContext. There should be a property there like:
public DbSet<UserAccount> UserAccounts { get; set; }
Regardless of whether you end up using the generic Set<T> accessor, you still must defined a DbSet for the entity on your context.
That said, you should absolutely not be creating your own service collection inside your repo. Register your context and your repo with the main service collection in Startup.cs and then simply inject your repo where you need it. The DI framework will take care of instantiating it with your context, as long as you have a constructor that takes your context (which you seem to).
And that said, you should ditch the repo entirely. It still requires a dependency on Entity Framework and doesn't do anything but proxy to Entity Framework methods. This is just an extra thing you have to maintain and test with no added benefit.
TLDR version: I'm having trouble getting my DDD domain model to work with NHibernate. If my value object itself contains a collection of value objects, I can't assign a new value without getting an NHibernate exception, and want to know what the best practice is in this situation.
Longer version:
Say I have an entity which contains a value object as a property, ValueObjectA, which itself contains a set of a different value objects of type ValueObjectB.
ValueObjectB only exists meaningfully as a property of ValueObjectA, i.e. if myEntity.ValueObjectA == null, it doesn't make sense for ValueObjectB to exist either.
I've written some example code to illustrate what I mean, with simplifications for brevity.
public class Entity
{
public int Id { get; private set; }
public ValueObjectA ValueObjectA { get; set; }
// Constructor: public Entity(ValueObjectA valueObjectA)
}
public class ValueObjectA : IEquatable<ValueObjectA>
{
public string X { get; private set; }
public ISet<ValueObjectB> ValueObjectBs { get; private set; }
// Constructor: public ValueObjectA(string x, ISet<ValueObjectB> valueObjectBs)
// Implementation of Equals/GetHahcode
}
public class ValueObjectB : IEquatable<ValueObjectB>
{
public int Y { get; private set; }
public int Z { get; private set; }
// Constructor: public ValueObjectB(int y, int z)
// Implementation of Equals/GetHahcode
}
I have a corresponding mapping class using mapping by code:
public class EntityMap : ClassMapping<Entity>
{
public EntityMap()
{
Table("Entity");
Id(x => x.Id, map => map.Generator(Generators.Identity));
Component(x => x.ValueObjectA, c =>
{
c.Property(x => x.X);
// Component relation is equilavent to <composite-element> in xml mappings
c.Set(x => x.ValueObjectBs, map =>
{
map.Table("ValueObjectB");
map.Inverse(true);
map.Cascade(Cascade.All | Cascade.DeleteOrphans);
map.Key(k => k.Column("Id"));
}, r => r.Component(ce =>
{
ce.Property(x => x.Y);
ce.Property(x => x.Z);
}));
});
}
}
The properties of ValueObjectA are mapped to the Entity table, but the properties of ValueObjectA.ValueObjectB are mapped to another table, since it is a one to many relationship. When a ValueObjectB is removed, I want that row to be deleted in the ValueObjectB table.
Since value objects are immutable, when I change the properties of entity.ValueObjectA, I should create a new instance of ValueObjectA. The problem is that the set of ValueObjectBs is a reference type, so when I try to save the entity with a different ValueObjectA, NHibernate will throw an exception because the original set that NHibernate is tracking is no longer referenced:
A collection with cascade="all-delete-orphan" was no longer referenced
by the owning entity instance.
Consider the following code:
var valueObjectBs_1 = new HashSet<ValueObjectB>
{
new ValueObjectB(1, 2),
new ValueObjectB(3, 4)
};
var valueObjectA_1 = new ValueObjectA("first", valueObjectBs_1);
var entity = new Entity(valueObjectA_1);
// Save entity, reload entity
var valueObjectBs_2 = new HashSet<ValueObjectB>
{
new ValueObjectB(1, 2)
};
var valueObjectA_2 = new ValueObjectA("second", valueObjectBs_2);
entity.ValueObjectA = valueObjectA_2;
// Save entity again
// NHIBERNATE EXCEPTION
I've managed to get around this by creating another ValueObjectA in order to preserve the reference to the set, e.g.
valueObjectA_1.ValueObjectBs.Remove(new ValueObjectB(3, 4));
entity.ValueObjectA = new ValueObjectA(valueObjectA_2.X, valueObjectA_1.ValueObjectBs);
However... that feels like a code smell - even if I wrote a custom setter for Entity.ValueObjectA, the implementation is starting to get complicated where the design is supposed to be simple.
public class Entity
{
// ...
private ValueObjectA valueObjectA;
public ValueObjectA ValueObjectA
{
// get
set
{
// Add/Remove relevant values from ValueObjectA.ValueObjectBs
valueObjectA = new ValueObjectA(value.X, ValueObjectA.ValueObjectBs);
}
}
}
What is the best practice in this type of situation? Or is this a sign that I'm trying to do something which violates the principles of DDD?
What you have is an anemic domain model.
You should replace public setters of the entity with methods that have meaningful names from the Ubiquitous language, that check the invariants and that do all the necessary cleanup in case of value objects replacements.
Although it may seem that things are more complicated this is payed back by the fact the now the entity is in full control about what happens with its internals. You now have full encapsulation.
I have a class in Entity framework 5 (using MVC 4):
public class JobFunction
{
public int Id { get; set; }
public string JobFunctionName { get; set; }
public int StatusId { get; set; }
public Status JFStatus { get; set; }
}
In my OnModelCreating method, I establish a FK relationship with the Status table as follows:
modelBuilder.Entity<JobFunction>().HasRequired(a => a.JFStatus).
WithMany().HasForeignKey(u => u.StatusId).WillCascadeOnDelete(false);
In my controller, I get a list of JobFunction objects as follows:
List<JobFunction> jfList = uow.JobFunctionRepository.GetAll().ToList<Catalog>();
where uow is my Unit of Work object, and JobFunctionRepository is defined. When I examine any JobFunction object in jfList, I see the following in my watch window:
Id: 1
JfStatus: null
JobFunctionName: "Manager"
StatusId: 2
Note that JFStatus is null. My question is: what provisions do I make in my code to initialize JFStatus to the appropriate Status object (based on the value of StatusId), during my GetAll call?
Thanks in advance.
-Zawar
You need some instrument to apply eager loading when you load the data through your repository. For example you could give your GetAll method a parameter list of expressions for the navigation properties you want to include in your query:
using System.Data.Entity;
//...
public IQueryable<JobFunction> GetAll(
params Expression<Func<JobFunction, object>>[] includes)
{
IQueryable<JobFunction> query = context.JobFunctions;
foreach (var include in includes)
query = query.Include(include);
return query;
}
Then you call it like so:
List<JobFunction> jfList = uow.JobFunctionRepository
.GetAll(jf => jf.JFStatus)
.ToList();
The JFStatus property should be filled now.