I'm trying to write some activities with C# instead of the designer and XAML. VS2010 has been buggy and very slow for that, and it also has very poor compilation support (for variables names, properties and so on).
So I'm trying to create activities by inheriting from the Activity class directly, but I'm encountering a snag.
Here's my code:
public class TestActivity : Activity
{
public InArgument<string> Username { get; set; }
public InArgument<string> Password { get; set; }
public OutArgument<bool> ValidCredential { get; set; }
public OutArgument<ProvisioningRole> Role { get; set; }
public OutArgument<Guid> Guid { get; set; }
protected override Func<Activity> Implementation
{
get
{
return () =>
{
return new Sequence()
{
Activities =
{
new AuthenticateUserActivity()
{
Username = this.Username,
Password = this.Password,
Guid = this.Guid,
Result = this.ValidCredential
},
new If()
{
Condition = this.ValidCredential,
Then = new GetUserRoleActivity()
{
Username = this.Username,
Password = this.Password,
Result = this.Role
}
},
}
};
};
}
set { base.Implementation = value; }
}
}
The problem is with the If(), the condition. It's supposed to be an InArgument, but this.ValidCredential is an OutArgument. I've tried creating a Variable, assign the value of ValidCredential to it. I also tried to put the result of AuthenticateUserActivity in the variable and then assign it to ValidCredential, but I get an error saying the To property of Assign needs to be specified.
I've looked around for proper tutorials, but all I found was an MSDN article that had a quick and dirty code implementation, and it used literals instead of the passed arguments, so no help from there.
I found out how to do it. You just need to create new InArgument from the original one. There is a constructor that takes an expression for it.
Username = new InArgument<bool>((ActivityContext c) => this.ValidCredential.Get(c))
So I changed my whole activity to
return new CompensableActivity()
{
Body = new Sequence()
{
Activities =
{
new AuthenticateUserActivity()
{
Username = this.Username.In(),
Password = this.Password.In(),
Guid = this.Guid.Out(),
Result = this.ValidCredential.Out()
},
new If(this.ValidCredential.In())
{
Then = new GetUserRoleActivity()
{
Username = this.Username.In(),
Password = this.Password.In(),
Result = this.Role.Out()
},
Else = new Assign<ProvisioningRole>()
{
To = this.Role.Out(),
Value = ProvisioningRole.User
}
}
}
},
};
In and Out being extension methods I wrote:
public static class WorkflowExtensions
{
#region In
public static InArgument<T> In<T>(this InArgument<T> self)
{
return new InArgument<T>(context => self.Get(context));
}
public static InArgument<T> In<T>(this OutArgument<T> self)
{
return new InArgument<T>(context => self.Get(context));
}
#endregion
#region Out
public static OutArgument<T> Out<T>(this InArgument<T> self)
{
return new OutArgument<T>(context => self.Get(context));
}
public static OutArgument<T> Out<T>(this OutArgument<T> self)
{
return new OutArgument<T>(context => self.Get(context));
}
#endregion
}
And now all is well!
You should be able to get this to work. The basic approach should be to use a Variable to store data, use an OutArgument to get data out of activities into the Variable and InArguments to get data from a Variable into an activity.
Also note that the expressions to tie InArguments to Variables are VisualBasicValue expressions. So something like:
Condition = new VisualBasicValue("System.DateTime.Now.Hour < 12")
This blog post isn't about using arguments and variables but shows a couple of examples.
Going to shamelessly plug my own library that I ended up making for this:
http://code.google.com/p/system-transactions/
Allows basic compensation of code without the ginormous hassle of WF. Also, compiles properly and is easily debuggable.
Related
I have a public Dictionary<string, PostRenewalActionJobs> Jobs to store some actions I would like to trigger for specific accounts, the key of this dictionary being the account name.
public class PostRenewalActionJobs
{
public List<AlterDatabaseLinkJob> AlterDataBaseLink { get; set; }
public DatabaseConnectionCheckJob DatabaseConnectionCheck { get; set; }
public UnlockDatabaseAccountJob UnlockDatabaseAccount { get; set; }
public LinuxConnectionCheckJob LinuxConnectionCheck { get; set; }
public WindowsConnectionCheckJob WindowsConnectionCheck { get; set; }
public ReplacePasswordInFileJob ReplacePasswordInFile { get; set; }
}
The properties of PostRenewalActionJobs type (AlterDataBaseLink, DatabaseConnectionCheck, etc) can be defined for a specific account or for all accounts by using * as key in the dictionary:
By using below method I am able to retrieve the jobs for an account (if exists) or the general jobs:
public PostRenewalActionJobs GetJobsForAccount(string accountName)
{
return Jobs.ContainsKey(accountName) ? Jobs[accountName] : Jobs["*"];
}
I would like to have a dynamic way of getting a job from the all accounts object ("*") if the one from the specific account is null.
Something like below but whit out repeating the same code for all job types and also a solution that should work when new job types are introduced.
var dbConCheckJob = GetJobsForAccount("someAccount").AlterDataBaseLink;
if(dbConCheckJob == null || !dbConCheckJob.Any())
{
dbConCheckJob = GetJobsForAccount("*").AlterDataBaseLink
}
I was thinking to use some reflection, but I am not sure how to do it.
You don't need to use reflection. You can already determine whether to get the specific jobs for an account or the generic ones, you could then use a Func to get the job you want:
public TJob GetPostJobForAccount<TJob>(string accountName,
Func<PostRenewalActionJobs, TJob> jobSelector) where TJob : JobBase
{
var genericJobs = Jobs["*"];
var accountJobs = Jobs.ContainsKey(accountName) ? Jobs[accountName] : genericJobs;
// Account might be defined but without any job of the given type
// hence selecting from the defaults if need be
return jobSelector(accountJobs) ?? jobSelector(genericJobs);
}
var bobJob = GetPostJobForAccount("bob", x => x.WindowsConnectionCheck);
var aliceJob = GetPostJobForAccount("alice", x => x.UnlockDatabaseAccount);
I found a way to do it, not sure if there is a better way:
public TJob GetPostJobForAccount<TJob>(string accountName)
{
Type type = typeof(PostRenewalActionJobs);
var accountJobs = Jobs[accountName];
var generalJobs = Jobs["*"];
foreach (var item in type.GetProperties())
{
var itemType = item.PropertyType;
var currentType = typeof(TJob);
if (itemType != currentType)
{
continue;
}
var output = (TJob)accountJobs?.GetType()?.GetProperty(item.Name)?.GetValue(accountJobs, null);
if (output is null)
{
output = (TJob)accountJobs?.GetType()?.GetProperty(item.Name)?.GetValue(generalJobs, null);
}
return output;
}
return default;
}
So I'm making a game, and it saves users' progress on the computer in a binary file. The User class stores a few things:
Integers for stat values (Serializable)
Strings for the Username and the skin assets
Lists of both the Achievement class and the InventoryItem class, which I have created myself.
Here are the User fields:
public string Username = "";
// ID is used for local identification, as usernames can be changed.
public int ID;
public int Coins = 0;
public List<Achievement> AchievementsCompleted = new List<Achievement>();
public List<InventoryItem> Inventory = new List<InventoryItem>();
public List<string> Skins = new List<string>();
public string CurrentSkinAsset { get; set; }
The Achievement class stores ints, bools, and strings, which are all serializable. The InventoryItem class stores its name (a string) and an InventoryAction, which is a delegate that is called when the item is used.
These are the Achievement class's fields:
public int ID = 0;
public string Name = "";
public bool Earned = false;
public string Description = "";
public string Image;
public AchievmentDifficulty Difficulty;
public int CoinsOnCompletion = 0;
public AchievementMethod OnCompletion;
public AchievementCriteria CompletionCriteria;
public bool Completed = false;
And here are the fields for the InventoryItem class:
InventoryAction actionWhenUsed;
public string Name;
public string AssetName;
The source of the InventoryAction variables are in my XNAGame class. What I mean by this is that the XNAGame class has a method called "UseSword()" or whatever, which it passes into the InventoryItem class. Previously, the methods were stored in the Game1 class, but the Game class, which Game1 inherits from, is not serializable, and there's no way for me to control that. This is why I have an XNAGame class.
I get an error when trying to serialize: "The 'SpriteFont' class is not marked as serializable", or something like that. Well, there is a SpriteFont object in my XNAGame class, and some quick tests showed that this is the source of the issue. Well, I have no control over whether or not the SpriteFont class is Serializable.
Why is the game doing this? Why must all the fields in the XNAGame class be serializable, when all I need is a few methods?
Keep in mind when answering that I'm 13, and may not understand all the terms you're using. If you need any code samples, I'll be glad to provide them for you. Thanks in advance!
EDIT: One solution I have thought of is to store the InventoryAction delegates in a Dictionary, except that this will be a pain and isn't very good programming practice. If this is the only way, I'll accept it, though (Honestly at this point I think this is the best solution).
EDIT 2: Here's the code for the User.Serialize method (I know what I'm doing in inefficient, and I should use a database, blah, blah, blah. I'm fine with what I'm doing now, so bear with me.):
FileStream fileStream = null;
List<User> users;
BinaryFormatter binaryFormatter = new BinaryFormatter();
try
{
if (File.Exists(FILE_PATH) && !IsFileLocked(FILE_PATH))
{
fileStream = File.Open(FILE_PATH, FileMode.Open);
users = (List<User>)binaryFormatter.Deserialize(fileStream);
}
else
{
fileStream = File.Create(FILE_PATH);
users = new List<User>();
}
for (int i = 0; i < users.Count; i++)
{
if (users[i].ID == this.ID)
{
users.Remove(users[i]);
}
}
foreach (Achievement a in AchievementsCompleted)
{
if (a.CompletionCriteria != null)
{
a.CompletionCriteria = null;
}
if (a.OnCompletion != null)
{
a.OnCompletion = null;
}
}
users.Add(this);
fileStream.Position = 0;
binaryFormatter.Serialize(fileStream, users);
You cannot serialize a SpriteFont by design, actually this is possible (.XNB file) but it hasn't been made public.
Solution:
Strip it off your serialized class.
Alternatives:
If for some reasons you must serialize some font, the first thing that comes to my mind would be to roll-out your own font system such as BMFont but that's a daunting task since you'll have to use it everywhere else where you might already do ...
Generate a pre-defined amount of fonts (i.e. Arial/Times/Courier at size 10/11/12 etc ...) using XNA Content app (can't recall its exact name); then store this user preference as two strings. With a string.Format(...) you should be able to load the right font back quite easily.
Alternative 2 is certainly the easiest and won't take more than a few minutes to roll-out.
EDIT
Basically, instead of saving a delegate I do the following:
inventory items have their own type
each type name is de/serialized accordingly
their logic does not happen in the main game class anymore
you don't have to manually match item type / action method
So while you'll end up with more classes, you have concerns separated and you can keep your main loop clean and relatively generic.
Code:
public static class Demo
{
public static void DemoCode()
{
// create new profile
var profile = new UserProfile
{
Name = "Bill",
Gold = 1000000,
Achievements = new List<Achievement>(new[]
{
Achievement.Warrior
}),
Inventory = new Inventory(new[]
{
new FireSpell()
})
};
// save it
using (var stream = File.Create("profile.bin"))
{
var formatter = new BinaryFormatter();
formatter.Serialize(stream, profile);
}
// load it
using (var stream = File.OpenRead("profile.bin"))
{
var formatter = new BinaryFormatter();
var deserialize = formatter.Deserialize(stream);
var userProfile = (UserProfile) deserialize;
// set everything on fire :)
var fireSpell = userProfile.Inventory.Items.OfType<FireSpell>().FirstOrDefault();
if (fireSpell != null) fireSpell.Execute("whatever");
}
}
}
[Serializable]
public sealed class UserProfile
{
public string Name { get; set; }
public int Gold { get; set; }
public List<Achievement> Achievements { get; set; }
public Inventory Inventory { get; set; }
}
public enum Achievement
{
Warrior
}
[Serializable]
public sealed class Inventory : ISerializable
{
public Inventory() // for serialization
{
}
public Inventory(SerializationInfo info, StreamingContext context) // for serialization
{
var value = (string) info.GetValue("Items", typeof(string));
var strings = value.Split(';');
var items = strings.Select(s =>
{
var type = Type.GetType(s);
if (type == null) throw new ArgumentNullException(nameof(type));
var instance = Activator.CreateInstance(type);
var item = instance as InventoryItem;
return item;
}).ToArray();
Items = new List<InventoryItem>(items);
}
public Inventory(IEnumerable<InventoryItem> items)
{
if (items == null) throw new ArgumentNullException(nameof(items));
Items = new List<InventoryItem>(items);
}
public List<InventoryItem> Items { get; }
#region ISerializable Members
public void GetObjectData(SerializationInfo info, StreamingContext context)
{
var strings = Items.Select(s => s.GetType().AssemblyQualifiedName).ToArray();
var value = string.Join(";", strings);
info.AddValue("Items", value);
}
#endregion
}
public abstract class InventoryItem
{
public abstract void Execute(params object[] objects);
}
public abstract class Spell : InventoryItem
{
}
public sealed class FireSpell : Spell
{
public override void Execute(params object[] objects)
{
// using 'params object[]' a simple and generic way to pass things if any, i.e.
// var world = objects[0];
// var strength = objects[1];
// now do something with these !
}
}
Okay, so I figured it out.
The best solution was to use a Dictionary in the XNAGame class, which stores two things: an ItemType (an enumeration), and an InventoryAction. Basically, when I use an item, I check it's type and then look up it's method. Thanks to everyone who tried, and I'm sorry if the question was confusing.
I've been searching all day and can't find a solution to this...
I have an EntityCollection of Communication objects which each have an instance of an Intention object(one-to-one).
I also have a User object which has many instances of UserLocation EntityObjects(one-to-many)
Intention objects have a property UID.
UserLocation objects have a property LID.
I want to write a LINQ expression which returns all Communication objects where the UID property of the Intention instance associated to a Communication object equals ANY LID property of ANY instance of a UserLocation instance for a User object.
I've tried this
return _context.Communications.Where
(u => u.Intention.UID.Equals
(user.UserLocations.Select
(p => p.LID)));
and this
return _context.Communications.Where
(u => user.UserLocations.Any
(x => x.LID.Equals
(u.Intention.UID)));
and this
var thislist = from Intentions in _context.Intentions
join UserLocations in user.UserLocations
on Intentions.UID equals UserLocations.LID
select Intentions.UID;
return _context.Communications.Where(u => u.Intention.Equals(thislist.Any()));
and this
var lidlist = user.UserLocations.Select(x => x.LID);
return _context.Communications.Where(x=> lidlist.Contains(x.Intention.UID)).ToList();
(this gives me an error on the Contains statement saying "Delegate System.Func<Communication,int,bool> does not take 1 argument", don't know how to fix)
Along with all these variations I have also:
modified my method to return IQueryable<Communication> and have also tried List<Communication> while appending ToList() to my queries.
Nothing works. Regardless of what I try I always end up with this exception
NotSupportedException was unhandled by user code
Unable to create a constant value of type 'PreparisCore.BusinessEntities.UserLocation'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.
What am i doing wrong??
Given this code:
namespace CollectionsWithIntentions
{
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
internal class Program
{
#region Methods
private static void Main(string[] args)
{
var communications = new[]
{
new Communication { Intention = new Intention { UID = 1 } },
new Communication { Intention = new Intention { UID = 2 } },
new Communication { Intention = new Intention { UID = 3 } },
new Communication { Intention = new Intention { UID = 4 } },
};
var users = new[]
{
new User { UserLocations = new List<UserLocation>(new[] { new UserLocation { LID = 2 },new UserLocation{LID=5} }) },
new User { UserLocations = new List<UserLocation>(new[] { new UserLocation { LID = 3 } }) }
};
IEnumerable<Communication> res =
communications.Where(w => users.Any(a => a.UserLocations.Any(b=>b.LID == w.Intention.UID)));
foreach (Communication communication in res)
{
Trace.WriteLine(communication);
}
}
#endregion
}
internal class Communication
{
#region Public Properties
public Intention Intention { get; set; }
#endregion
#region Public Methods and Operators
public override string ToString()
{
return string.Concat("Communication-> Intention:", this.Intention.UID);
}
#endregion
}
internal class Intention
{
#region Public Properties
public int UID { get; set; }
#endregion
}
internal class User
{
#region Public Properties
public List<UserLocation> UserLocations { get; set; }
#endregion
}
internal class UserLocation
{
#region Public Properties
public int LID { get; set; }
#endregion
}
}
I get this result:
Communication-> Intention:2
Communication-> Intention:3
Am I missing anything?
From the last two compiler errors you have linked in one of your comments...
...I would conclude that Intention.UID is a nullable type int? and not a not-nullable int as you said in the comments. This indeed doesn't compile. Try to change your last query to:
var lidlist = user.UserLocations.Select(x => x.LID);
return _context.Communications
.Where(x => x.Intention.UID.HasValue
&& lidlist.Contains(x.Intention.UID.Value))
.ToList();
The other three queries do not work because user.UserLocations is a collection of a non-primitive custom type in memory (for the SQL query to be generated it is a "constant" value) and EF doesn't support to build a SQL query with such a constant custom type.
I dont know how to name the question properly, so fell free to change it. My question is, I have around 10 methods that look like:
[WebMethod(EnableSession = true)]
public string ReadUserAdditional()
{
EUser user = (EUser)Session["user"];
var json = new { result = true, user.Image, user.Biography };
return new JavaScriptSerializer().Serialize(json);
}
[WebMethod(EnableSession = true)]
public string ReadUserBasicInformation()
{
EUser user = (EUser)Session["user"];
var json = new { result = true, user.Name, user.Username};
return new JavaScriptSerializer().Serialize(json);
}
The methods are very similar, but they return different fields. Im thinking about refactoring all methods into one, receveing the fields to return as parameters. Is it a good idea? How can I do that? Reflection?
First of all you need to know that object and dictionary are presented in json simmilar.
[WebMethod(EnableSession = true)]
public string ReadUserAdditional()
{
return GetUserInfo(new []
{
new FieldInfo {Name = "Image", u => u.Image},
new FieldInfo {Name = "Biography", u => u.Biography}
});
}
private string GetUserInfo(FieldInfo[] infos)
{
EUser user = (EUser)Session["user"];
var dict = new Dictionary<string, object>{ { "result", true } };
foreach(var info in infos)
{
dictionary.Add(info.Name, info.Accessor(user));
}
return new JavaScriptSerializer().Serialize(dict );
}
public class FieldInfo
{
public Func<EUser, object> Accessor { get; set; }
public string Name { get; set;}
}
I don't think it's a terrible idea, especially if you have tons of these methods and want to simplify your API.
A few downsides:
1) Reflection comes at a perf cost. This probably doesn't matter a whole lot unless you're the size of Twitter.
2) There would potentially be security concerns if the data had any properties you do NOT wanting users getting access to, such as some sort of internal database keys or what not. Make sure every property on your class is one you're totally okay becoming public information.
You can use a lambda to refactor away the duplication:. This would reduce all your methods to a single line of code:
[WebMethod(EnableSession = true)]
public string ReadUserAdditional()
{
return GetUserJSON(x => new { result = true, x.Image, x.Biography });
}
[WebMethod(EnableSession = true]
public string ReadUserBasicInformation()
{
return GetUserJSON(x => new { result = true, x.Name, x.UserName });
}
private string GetUserJSON(Func<EUser, string> jsonFields)
{
EUser user = (EUser)Session["user"];
var json = jsonFields(user);
return new JavaScriptSerializer().Serialize(json);
}
Another approach is to use Automapper or similar library to project your data.
[WebMethod(EnableSession = true)]
public string ReadUserAdditional()
{
return GetUserInfo<UserAdditionalDto>();
}
private string GetUserInfo<TDto>(FieldInfo[] infos)
{
EUser user = (EUser)Session["user"];
var dto = Mapper.Map<TDto>(user); // Mapper is Automapper entry class.
return new JavaScriptSerializer().Serialize(dto );
}
public class UserAdditionalDto
{
public string Image { get; set; }
public string Biography { get; set;}
}
Is it possible to modify the attribute of a property at runtime?
let's say I have some class:
public class TheClass
{
[TheAttribute]
public int TheProperty { get; set; }
}
Is there a way to do this?
if (someCondition)
{
// disable attribute. Is this possible and how can this be done?
}
No this is not possible. You cannot modify attribute values from metadata, or metadata in general, at runtime
Strictly speaking the above is not true. There are certain APIs which do allow allow for some metadata generation and modification. But they are very scenario specific, (ENC, profiling, debugging) and should not be used in general purpose programs.
It depends; from a reflection perspective: no. You can't. But if you are talking about attributes used by System.ComponentModel in things like data-binding, they you can use TypeDescriptor.AddAttributes to append extra attributes. Or other customer models involving custom descriptors. So it depends on the use-case.
In the case of xml serialization, it gets more interesting. Firstly, we can use fun object models:
using System;
using System.Xml.Serialization;
public class MyData
{
[XmlAttribute]
public int Id { get; set; }
[XmlAttribute]
public string Name { get; set; }
[XmlIgnore]
public bool NameSpecified { get; set; }
static void Main()
{
var ser = new XmlSerializer(typeof(MyData));
var obj1 = new MyData { Id = 1, Name = "Fred", NameSpecified = true };
ser.Serialize(Console.Out, obj1);
Console.WriteLine();
Console.WriteLine();
var obj2 = new MyData { Id = 2, Name = "Fred", NameSpecified = false };
ser.Serialize(Console.Out, obj2);
}
}
The bool {name}Specified {get;set;} pattern (along with bool ShouldSerialize{name}()) is recognised and used to control which elements to include.
Another alternative is to use the non-default ctor:
using System;
using System.Xml.Serialization;
public class MyData
{
[XmlAttribute]
public int Id { get; set; }
public string Name { get; set; }
static void Main()
{
var obj = new MyData { Id = 1, Name = "Fred" };
XmlAttributeOverrides config1 = new XmlAttributeOverrides();
config1.Add(typeof(MyData),"Name",
new XmlAttributes { XmlIgnore = true});
var ser1 = new XmlSerializer(typeof(MyData),config1);
ser1.Serialize(Console.Out, obj);
Console.WriteLine();
Console.WriteLine();
XmlAttributeOverrides config2 = new XmlAttributeOverrides();
config2.Add(typeof(MyData), "Name",
new XmlAttributes { XmlIgnore = false });
var ser2 = new XmlSerializer(typeof(MyData), config2);
ser2.Serialize(Console.Out, obj);
}
}
Note though that if you use this second approach you need to cache the serializer instance, as it emits an assembly every time you do this. I find the first approach simpler...
Attributes are baked into code at compilation time. The only way you can define new attributes at run time is to generate new code at runtime (using Reflection.Emit, for example). But you cannot change the attributes of existing code.
You can put Boolean variable in the class to disable/enable the property instead of disabling it at run time.
You might want to look at this http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/5b0d356d-d006-43ff-bfcd-aa90dd8de6db
And Dave Morton's explanation on this blog http://blog.codinglight.com/2008/10/changing-attribute-parameters-at.html
Sounds like you want to consider implementing IXmlSerializable
You can implement IDataErrorInfo, then check range in Validate method.
public string this[string property] {
get { return Validate(property); }
}
public string Error { get; }
protected virtual string Validate(string property) {
var propertyInfo = this.GetType().GetProperty(property);
var results = new List<ValidationResult>();
var result = Validator.TryValidateProperty(
propertyInfo.GetValue(this, null),
new ValidationContext(this, null, null) {
MemberName = property
},
results);
if (!result) {
var validationResult = results.First();
return validationResult.ErrorMessage;
}
return string.Empty;
}
In sub class
protected override string Validate(string property) {
Debug.WriteLine(property);
if (property == nameof(YourProperty)) {
if (_property > 5) {
return "_property out of range";
}
}
return base.Validate(property);
}