I'm writing an Ocean plugin for Petrel and need to persist some custom domain objects, and everything seems to point to using a structured archive data source. I've created a common class to hold a lot of the standard domain object stuff (droid, name, color, image, comments, history, etc), to avoid rewriting it for every domain object I create. The Ocean development guide only has simple examples of classes with no inheritance, but given that everything has a version number, I foresee a potential problem when the base class version is different than the version of inherited-class-1 which is different than inherited-class-2, and then I update something in the base class.
Is it possible to use a structured archive with the common base class? Are there any special considerations for versioning, or anything else I need to be aware of?
ETA: A simple class diagram showing the relationships and some stuff I've tried
public abstract class ClassA
|
-----------------------------------
| |
public class ClassB : ClassA public classC : ClassA
public class ClassD
{
private List<ClassA> _myClassAObjects;
}
All classes are marked Archivable, and in ClassD, _myClassAObjects is marked Archived. Everything saves OK, but when I load, I get an InvalidCastException, as it tries to cast the List<ClassB> to a List<ClassA>. The casting should work, since ClassB inherits from ClassA, should it not?
Got an answer from Schlumberger. It is possible, by doing something like this:
[Archivable]
public abstract class Abstract CDO
{
[ArchivableContextInject]
protected StructuredArchiveDataSource DataSourceCore;
[Archived(Name = "Name")]
private string _name;
private AbstractCDO _parent;
[Archived(Name="ParentDroid")]
private Droid _parentDroid;
[Archived(Name = "Droid")]
protected Droid DroidCore
{
get { return _droid; }
set
{
if (_droid != value)
{
DataSourceCore.IsDirty = true;
_droid = value;
}
}
}
public Droid ParentDroid
{
get { return _parentDroid; }
set
{
if (_parentDroid != value)
{
DataSourceCore.IsDirty = true;
_parentDroid = value;
}
}
}
public AbstractCDO Parent
{
get { return _parent; }
set
{
if (_parent != value)
{
DataSourceCore.IsDirty = true;
_parent = value;
_parentDroid = _parent.Droid;
}
}
}
protected AbstractCDO(string name)
{
_name = name;
DataSourceCore = Factory.Get();
_droid = DataSourceCore.GenerateDroid();
DataSourceCore.AddItem(_droid, this);
}
}
[Archivable]
public abstract class AbstractCDOCollection : AbstractCDO, IObservableElementList
{
[Archived]
private List<AbstractCDO> _children;
protected AbstractCDO(string name) : base(name) { }
public List<AbstractCDO> Children
{
get { return _children; }
}
}
[Archivable]
public class ConcreteObject : AbstractCDO
{
public ConcreteObject(string name) : base(name)
{
// other stuff
}
}
The DataSource property needs to be protected since the injection had a bug which was fixed in Petrel 2013.3 / 2014.1.
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
}
What is the best way to do the following:
Suppose I have a class called Person and many derived classes for specialized persons.
Suppose at the beginning of my app, I know I have to deal with a person but I won't know what kind of person it is until much later (something beyond my control so I cannot determine the Person type at the beginning).
So at the beginning I will create a Person and fill in attributes for it. Later, when I know what kind of Person it is, I would instantiate a specialized person and copy over the any saved attributes for her.
Is there a more elegant way to do this without creating two objects?
If you don't know the type of person up front, you won't be able to avoid instantiating two objects. There has to be something to contain the base Person attributes before you know the specialized person, but you can't take advantage of polymorphism without instantiating the specialized object later.
One option is to use a composition pattern, in which each specialized person contains a Person instance rather than inheriting from it. You still have to instantiate two objects, but you don't have to rewrite the code to copy over the saved attributes every time. Here's an example (C# syntax):
public interface IPerson
{
string Name { get; }
int Age { get; }
}
public class Person : IPerson
{
public string Name { get; private set; }
public int Age { get; private set; }
public Person(string name, int age)
{
Name = name;
Age = age;
}
}
public abstract class SpecialPersonBase : IPerson
{
private IPerson myPerson;
protected SpecialPersonBase(IPerson person)
{
myPerson = person;
}
public string Name { get { return myPerson.Name; } }
public int Age { get { return myPerson.Age; } }
public abstract string Greet();
}
public class Doctor : SpecialPersonBase
{
public Doctor(IPerson person) : base(person) { }
public override string Greet()
{
return "How are you feeling?";
}
}
public class Accountant : SpecialPersonBase
{
public Accountant(IPerson person) : base(person) { }
public override string Greet()
{
return "How are your finances?";
}
}
You could use the classes like this:
IPerson bob = new Person("Bob", "25");
// Do things with the generic object
// until you can determine the specific type
SpecialPerson specialBob;
if (bobIsDoctor)
{
specialBob = new Doctor(bob);
}
else if (bobisAccountant)
{
specialBob = new Accountant(bob);
}
specialBob.Greet();
I wonder how to add state to the chain of decorators that will be available to the consumer. Given this simplified model:
abstract class AbstractPizza
{
public abstract print(...);
}
class Pizza : AbstractPizza
{
public int Size { get; set; }
public print(...);
}
abstract class AbstractPizzaDecorator
{
public Pizza:AbstractPizza;
public abstract print();
}
class HotPizzaDecorator : AbstractPizzaDecorator
{
public int Hotness { get; set; }
public print(...);
}
class CheesyPizzaDecorator : AbstractPizzaDecorator
{
public string Cheese { get; set; }
public print(...);
}
void Main()
{
BigPizza = new Pizza();
BigPizza.Size = 36;
HotBigPizza = new HotPizzaDecorator();
HotBigPizza.Pizza = BigPizza;
HotBigPizza.Hotness = 3;
HotBigCheesyPizza = new CheesyPizzaDecorator();
HotBigCheesyPizza.Pizza = HotBigPizza;
HotBigCheesyPizza.Cheese = "Blue";
HotBigCheesyPizza.print();
HotBigCheesyPizza.size = 28; // ERRRRRR !
}
Now if they all implement the print method and propagate that though the chain, it's all good. But how does that work for the state? I can't access the size property on the HotBigCheesyPizza.
What's the part that I'm missing? Wrong pattern?
Thanks for helping!
Cheers
The decorator pattern is for adding additional behavior to the decorated class without the client needing to adjust. Thus it is not intended for adding a new interface (e.g. hotness, cheese) to the thing being decorated.
A somewhat bad example of what it might be used for is where you want to change how size is calculated: you could create a MetricSizePizzaDecorator that converts the size to/from English/metric units. The client would not know the pizza has been decorated - it just calls getSize() and does whatever it needs to do with the result (for example, to calculate the price).
I would probably not use the decorator in my example, but the point is: it does not alter the interface. In fact, nearly all design patterns come down to that - adding variability to a design without changing interfaces.
one way of adding state is by using a self referential data structure (a list). but this uses the visitor pattern and does more than you probably want. this code is rewritten from A little Java, a few patterns
// a self referential data structure with different types of nodes
abstract class Pie
{
abstract Object accept(PieVisitor ask);
}
class Bottom extends Pie
{
Object accept(PieVisitor ask) { return ask.forBottom(this); }
public String toString() { return "crust"; }
}
class Topping extends Pie
{
Object topping;
Pie rest;
Topping(Object topping,Pie rest) { this.topping=topping; this.rest=rest; }
Object accept(PieVisitor ask) { return ask.forTopping(this); }
public String toString() { return topping+" "+rest.toString(); }
}
//a class to manage the data structure
interface PieManager
{
int addTopping(Object t);
int removeTopping(Object t);
int substituteTopping(Object n,Object o);
int occursTopping(Object o);
}
class APieManager implements PieManager
{
Pie p=new Bottom();
// note: any object that implements a rational version of equal() will work
public int addTopping(Object t)
{
p=new Topping(t,p);
return occursTopping(t);
}
public int removeTopping(Object t)
{
p=(Pie)p.accept(new RemoveVisitor(t));
return occursTopping(t);
}
public int substituteTopping(Object n,Object o)
{
p=(Pie)p.accept(new SubstituteVisitor(n,o));
return occursTopping(n);
}
public int occursTopping(Object o)
{
return ((Integer)p.accept(new OccursVisitor(o))).intValue();
}
public String toString() { return p.toString(); }
}
//these are the visitors
interface PieVisitor
{
Object forBottom(Bottom that);
Object forTopping(Topping that);
}
class OccursVisitor implements PieVisitor
{
Object a;
OccursVisitor(Object a) { this.a=a; }
public Object forBottom(Bottom that) { return new Integer(0); }
public Object forTopping(Topping that)
{
if(that.topping.equals(a))
return new Integer(((Integer)(that.rest.accept(this))).intValue()+1);
else return that.rest.accept(this);
}
}
class SubstituteVisitor implements PieVisitor
{
Object n,o;
SubstituteVisitor(Object n,Object o) { this.n=n; this.o=o; }
public Object forBottom(Bottom that) { return that; }
public Object forTopping(Topping that)
{
if(o.equals(that.topping))
that.topping=n;
that.rest.accept(this);
return that;
}
}
class RemoveVisitor implements PieVisitor
{
Object o;
RemoveVisitor(Object o) { this.o=o; }
public Object forBottom(Bottom that) { return new Bottom(); }
public Object forTopping(Topping that)
{
if(o.equals(that.topping))
return that.rest.accept(this);
else return new Topping(that.topping,(Pie)that.rest.accept(this));
}
}
public class TestVisitor
{
public static void main(String[] args)
{
// make a PieManager
PieManager pieManager=new APieManager();
// add some toppings
pieManager.addTopping(new Float(1.2));
pieManager.addTopping(new String("cheese"));
pieManager.addTopping(new String("onions"));
pieManager.addTopping(new String("cheese"));
pieManager.addTopping(new String("onions"));
pieManager.addTopping(new String("peperoni"));
System.out.println("pieManager="+pieManager);
// substitute anchovies for onions
int n=pieManager.substituteTopping(new String("anchovies"),new String("onions"));
System.out.println(n+" pieManager="+pieManager);
// remove the 1.2's
n=pieManager.removeTopping(new Float(1.2));
System.out.println(n+" pieManager="+pieManager);
// how many anchovies do we have?
System.out.println(pieManager.occursTopping(new String("anchovies"))+" anchovies");
}
}
I believe your component Pizza and your abstract decorator PizzaDecorator are supposed to share the same interface, that way each instance of the decorator is capable of the same operations as the core component Pizza.
I have spent some time writing code for my application assuming that the serialisation bit would be the easiest part of it. Pretty much both sides (client and server) are done and all I need to do is passing a class AccountInfo from the service to the client... The problem is that AccountInfo inherits List and therefore [DataContract] attribute is not valid. I tried using the [CollectionDataContract] attribute but then the class that is received on the other side (client) contains only generic List methods without my custom implemented properties such as GroupTitle...I have worked out a solution for this problem but I don't know how to apply it.
Basically everything works when I make a property instead of inheriting a List but then I can't bind this class to LongListSelector (WP7) because it's not a collection type.
There are three classes I'm on about. AccountInfo that contains multiple instances of: AccountInfoGroup that contains multiple instances of:AccountInfoEntry (this one does not inherit list therefore there are no problems serialising it and all properties are accessible).
Could someone help me using right attributes to serialise and transfer these classes using a WCF method?
Here is the code of 2 of these collection classes:
public class AccountInfo : List<AccountInfoGroup>
{
public AccountInfo()
{
UpdateTime = DateTime.UtcNow;
EntryID = Guid.NewGuid();
}
public bool HasItems
{
get
{
return (Count != 0);
}
private set
{
}
}
public Guid EntryID
{
get;
set;
}
public decimal GetTotalCredit()
{
decimal credit = 0;
foreach (AccountInfoGroup acg in this.Where(item => item.Class == AccountInfoEntry.EntryType.Credit))
{
acg.Where(item => item.ItemClass == AccountInfoEntry.EntryType.Credit).ToList().ForEach(entry =>
{ credit += entry.Remaining; }
);
}
return credit;
}
public bool UsedForCreditComparison = false;
public DateTime UpdateTime { get; private set; }
}
public class AccountInfoGroup : List<AccountInfoEntry>
{
public AccountInfoEntry.EntryType Class
{
get;
private set;
}
public string Title
{
get
{
return AccountInfoEntry.ClassToString(Class);
}
}
public AccountInfoGroup(AccountInfoEntry.EntryType groupClass)
{
this.#Class = groupClass;
}
public bool HasItems
{
get
{
return (Count != 0);
}
private set
{
}
}
}
Thank you for any suggestions... :)
The sample you had is quite painful for WCF in serialization.
What I suggest is you to revised and have a common models for your WCF messages (That means it only contains properties with getter and setter, serialization attributes).
If you have a problem in LongListSelector binding in WP7, you might want to convert the message to the actual type the WP7 object supports to use in binding.
With the following:
public class AClass
{
public ADependent Dependent { get; set; }
}
public class ADependent
{
public ADependent(AClass ownerValue) {}
}
with the following registrations...
builder.RegisterType<AClass>().PropertiesAutowired().InstancePerDependency();
builder.RegisterType<ADependent>().PropertiesAutowired().InstancePerDependency();
When I resolve an AClass, how do I make sure that 'ownerValue' is the instance of AClass being resolved, and not another instance? Thx
FOLLOW ON
The example above doesn't really catch the problem properly, which is how to wire up ADependent when registering when scanning... for example
public class AClass : IAClass
{
public IADependent Dependent { get; set; }
}
public class ADependent : IADependent
{
public ADependent(IAClass ownerValue) {}
}
// registrations...
builder.RegisterAssemblyTypes(assemblies)
.AssignableTo<IAClass>()
.As<IAClass>()
.InstancePerDependency()
.PropertiesAutowired();
builder.RegisterAssemblyTypes(assemblies)
.AssignableTo<IADependent>()
.As<IADependent>()
.InstancePerDependency()
.PropertiesAutowired();
The function I am looking for really is another relationship type like
public class ADependent : IADependent
{
public ADependent(OwnedBy<IAClass> ownerValue) {}
}
The OwnedBy indicates that ownerValue is the instance that caused ADependent to created. Does something like this make sense? It would certainly make wiring up UI components a breeze.
To extend Steven's approach, you can even Resolve() the second class, passing the first instance as a parameter:
builder.RegisterType<ADependent>();
builder.Register<AClass>(c =>
{
var a = new AClass();
a.Dependent = c.Resolve<ADependent>(TypedParameter.From(a));
return a;
});
You can register a lambda to do the trick:
builder.Register<AClass>(_ =>
{
var a = new AClass();
a.Dependent = new ADependent(a);
return a;
});