The main purpose is to show intellisense when setting the property. It would be great if I could do it via an attribute like the image below.
The property should remain a string(not enum or struct) so that Mongo's BsonSerializer can serialize it properly. Here is an example of what it might look like:
To help other developers on the team know possible (but not exlusive) values they can use for the Type field Code Completion should display values that can be used as shown below:
(Edited) I was able to solve this by creating my own type
public class SkinType:StringType<SkinType>
{
public SkinType(string value)
{
Value = value;
}
public SkinType()
{
}
public static implicit operator string(SkinType d)
{
return d.Value;
}
public static implicit operator SkinType(string d)
{
return new SkinType(d);
}
public const string StringValue = nameof(StringValue);
public const string Color = nameof(Color);
}
Now I get intellisense for my Type property and Mongo knows how to serialize it.
Here is how I use it:
public class Skin : ServiceMongoIdentity
{
//removed some properties for brevity.
[BsonIgnoreIfDefault]
[BsonDefaultValue(SkinType.StringValue)]
public SkinType Type { get; set; } = SkinType.StringValue;
}
Here is how the StringType base class is defined. I had to make Value public because Generics cannot have constructors with parameters
public abstract class StringType<T> where T :StringType<T>,new()
{
[ReadOnly(true)]
public string Value;
public T FromString(string d)
{
return new T
{
Value = d
};
}
public override bool Equals(object obj)
{
return obj?.ToString() == Value;
}
public override int GetHashCode()
{
return Value.GetHashCode();
}
public override string ToString()
{
return Value;
}
}
I have a config service which wraps the baked-in assembly settings, but I'd also like to override these on the command line.
Currently this code is working fine:
public interface ISettings
{
string Url { get; }
}
public class OperationalSettings : ISettings
{
public string Url { get { return ServiceSettings.Default.Url; } }
}
public class CommandLineModel
{
public string Url;
}
public class CommandLineSettings : ISettings
{
private readonly CommandLineModel _model;
public CommandLineSettings(string serialisedSettings)
{
_model = JsonConvert.DeserializeObject<CommandLineModel>(serialisedSettings);
}
public string Url { get { return _model.Url; } }
}
public class ConfigService
{
private readonly ISettings _settings;
public ConfigService(ISettings settings)
{
_settings = settings;
}
public ISettings settings { get { return _settings; } }
}
Then the test driver code:
class Program
{
static void Main(string[] args)
{
ISettings opSettings = new OperationalSettings();
var commandLineTest = "{Url:'http://overridenurl.com'}";
ISettings commandSettings = new CommandLineSettings(commandLineTest);
var configService = new ConfigService(opSettings);
var configServiceUsingCmdOpts = new ConfigService(commandSettings);
}
}
So with this I can override settings using the command line string. However, what I don't like is that if I have a new settings, I now need to add this in 4 places:
The interface
The concrete implementation of the settings wrapper (OperationalSettings)
The command line model for deserialisation
The command line settings implementation that wraps the deserialised model.
This seems to suffer from scalability once I add more properties. Is there a more efficient way to achieve this without so many code changes?
You might take a look at DynamicObject
public class CommandLineModelDictionary : DynamicObject
{
// The inner dictionary.
Dictionary<string, object> dictionary
= new Dictionary<string, object>();
// This property returns the number of elements
// in the inner dictionary.
public int Count
{
get
{
return dictionary.Count;
}
}
// If you try to get a value of a property
// not defined in the class, this method is called.
public override bool TryGetMember(
GetMemberBinder binder, out object result)
{
// Converting the property name to lowercase
// so that property names become case-insensitive.
string name = binder.Name.ToLower();
// If the property name is found in a dictionary,
// set the result parameter to the property value and return true.
// Otherwise, return false.
return dictionary.TryGetValue(name, out result);
}
// If you try to set a value of a property that is
// not defined in the class, this method is called.
public override bool TrySetMember(
SetMemberBinder binder, object value)
{
// Converting the property name to lowercase
// so that property names become case-insensitive.
dictionary[binder.Name.ToLower()] = value;
// You can always add a value to a dictionary,
// so this method always returns true.
return true;
}
}
Otherwise If you have a simple scenario in which you need an object that can only add and remove members at run time but that does not need to define specific operations and does not have static members, use the ExpandoObject class
here how to use
class Program
{
public static dynamic Dyn { get; set; }
static void Main(string[] args)
{
dynamic model= new CommandLineModelDictionary();
model.Prop1 = "Foo";
model.Prop2 = "toto";
Console.WriteLine(model.Prop1);
Console.WriteLine(model.Prop2);
//otherwise you can use
dynamic dynModel = new ExpandoObject();
dynModelop1 = "Test1";
dynModel2 = "Test2";
Console.WriteLine(dynModel.Prop1);
Console.WriteLine(dynModel.Prop2);
}
}
PropertyGrid... for users Id like to leave only several of them. But now I see all, and users would be confused when see something like Dock or Cursor and such...
Hope it's clear for now...
Use this attribute:
[Browsable(false)]
public bool AProperty {...}
For the inherited properties:
[Browsable(false)]
public override bool AProperty {...}
Another idea (since you are trying to hide all base class members):
public class MyCtrl : TextBox
{
private ExtraProperties _extraProps = new ExtraProperties();
public ExtraProperties ExtraProperties
{
get { return _extraProps; }
set { _extraProps = value; }
}
}
public class ExtraProperties
{
private string _PropertyA = string.Empty;
[Category("Text Properties"), Description("Value for Property A")]
public string PropertyA {get; set;}
[Category("Text Properties"), Description("Value for Property B")]
public string PropertyB { get; set; }
}
and then for your property grid:
MyCtrl tx = new MyCtrl();
pg1.SelectedObject = tx.ExtraProperties;
The down side is it changes your access level of those properties from
tx.PropertyA = "foo";
to
tx.ExtraProperties.PropertyA = "foo";
To hide MyCtrl properties, use [Browsable(False)] attribute on the property.
[Browsable(false)]
public bool AProperty { get; set;}
To hide inherited proeprties, you need to override the base and apply the browsable attribute.
[Browsable(false)]
public override string InheritedProperty { get; set;}
Note: You may need to add the virtual or new keyword depending on the circumstances.
A better approach would be to use a ControlDesigner. The designer has an override called PreFilterProperties that can be used to add extra attributes to the collection that has been extracted by the PropertyGrid.
Designer(typeof(MyControlDesigner))]
public class MyControl : TextBox
{
// ...
}
public class MyControlDesigner : ...
{
// ...
protected override void PreFilterProperties(
IDictionary properties)
{
base.PreFilterProperties (properties);
// add the names of proeprties you wish to hide
string[] propertiesToHide =
{"MyProperty", "ErrorMessage"};
foreach(string propname in propertiesToHide)
{
prop =
(PropertyDescriptor)properties[propname];
if(prop!=null)
{
AttributeCollection runtimeAttributes =
prop.Attributes;
// make a copy of the original attributes
// but make room for one extra attribute
Attribute[] attrs =
new Attribute[runtimeAttributes.Count + 1];
runtimeAttributes.CopyTo(attrs, 0);
attrs[runtimeAttributes.Count] =
new BrowsableAttribute(false);
prop =
TypeDescriptor.CreateProperty(this.GetType(),
propname, prop.PropertyType,attrs);
properties[propname] = prop;
}
}
}
}
You can add the names of proeprties you wish to hide to propertiesToHide which allows for a cleaner separation.
Credit where due: http://www.codeproject.com/KB/webforms/HidingProperties.aspx#
I'm tweaking a WinForms application. This application has a Form that contains a PropertyGrid. An object is assigned to the SelectedObject property so that the property grid displays the properties for the object.
The type of the object assigned has a property that carries an EditorAttribute specifying a UITypeEditor.
This implementation of UITypeEditor returns UITypeEditorEditStyle.Drop in its override of GetEditStyle method. Its EditValue method displays a ListBox from which a value for the instance property can be assigned.
All well an good so far.
Now I have an additional requirement which calls for the available items in the list to be modified based on other state held by the Form hosting the PropertyGrid. I can't work out how to get this contextual information to the EditValue method.
There doesn't seem to be anything on the context parameter even if I try casting it to more specific types. Neither can I work out how to add some other Service to retrieve from the provider.
Any ideas?
I was in similar situation, I wanted to inject an object into my custom UITypeEditor's constructor.
I followed Nicolas Cadilhac comment in Here, GIVE HIM ALL THE CREDIT. It uses TypeDescriptionProvider.
Here is the complete set of code.
class Foo
{
public Foo() { Bar = new Bar(); }
public Bar Bar { get; set; }
}
class Bar
{
public string Value { get; set; }
}
class BarTypeDescriptionProvider : TypeDescriptionProvider
{
private TypeDescriptionProvider _baseProvider;
string _extraParam;
public BarTypeDescriptionProvider(Type t, string extraParam)
{
this._extraParam = extraParam;
_baseProvider = TypeDescriptor.GetProvider(t);
}
public string ExtraParam
{
get { return _extraParam; }
}
public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance)
{
return new BarTypeDescriptor(this, _baseProvider.GetTypeDescriptor(objectType, instance), objectType);
}
}
class BarTypeDescriptor : CustomTypeDescriptor
{
private Type _objectType;
private BarTypeDescriptionProvider _provider;
public BarTypeDescriptor(BarTypeDescriptionProvider provider, ICustomTypeDescriptor descriptor, Type objectType): base(descriptor)
{
if (provider == null) throw new ArgumentNullException("provider");
if (descriptor == null)
throw new ArgumentNullException("descriptor");
if (objectType == null)
throw new ArgumentNullException("objectType");
_objectType = objectType;
_provider = provider;
}
public override object GetEditor(Type editorBaseType)
{
return new BarEditor(_provider.ExtraParam);
}
}
class BarEditor : UITypeEditor
{
private string _extraParam;
public BarEditor(string x)
: base()
{
_extraParam = x;
}
public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
{
return UITypeEditorEditStyle.Modal;
}
public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
{
MessageBox.Show(_extraParam);
return base.EditValue(context, provider, value);
}
}
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
string extraParam = "Extra param from main form";
TypeDescriptor.AddProvider(new BarTypeDescriptionProvider(typeof(Bar), extraParam), typeof(Bar));
this.propertyGrid1.SelectedObject = new Foo();
}
}
Michael
I wonder if what you are trying to do would would better as a TypeConverter via GetStandardValues? But either way, both context.Instance and context.PropertyDescriptor seem to be populated in a quick test (for both GetEditStyle and EditValue):
using System;
using System.ComponentModel;
using System.Drawing.Design;
using System.Windows.Forms;
class MyData
{
[Editor(typeof(MyEditor), typeof(UITypeEditor))]
public string Bar { get; set; }
public string[] Options { get; set; }
}
class MyEditor : UITypeEditor
{
public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
{
// break point here; inspect context
return UITypeEditorEditStyle.DropDown;
}
public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
{
// break point here; inspect context
return base.EditValue(context, provider, value);
}
}
class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form
{
Controls =
{
new PropertyGrid {
Dock = DockStyle.Fill,
SelectedObject = new MyData()
}
}
});
}
}
Or as a type-converter:
using System;
using System.ComponentModel;
using System.Windows.Forms;
class MyData
{
[TypeConverter(typeof(MyConverter))]
public string Bar { get; set; }
public string[] Options { get; set; }
}
class MyConverter : StringConverter
{
public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
{
return true;
}
public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
{
MyData data = (MyData)context.Instance;
if(data == null || data.Options == null) {
return new StandardValuesCollection(new string[0]);
}
return new StandardValuesCollection(data.Options);
}
}
class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form
{
Controls =
{
new PropertyGrid {
Dock = DockStyle.Fill,
SelectedObject = new MyData()
}
}
});
}
}
In the overridden EditValue method, context.Container will provide the object that the editor belongs to. The context.Container.Components property will list out all the controls which includes the form and all of its children.
I've created a class with properties that have default values. At some point in the object's lifetime, I'd like to "reset" the object's properties back to what they were when the object was instantiated. For example, let's say this was the class:
public class Truck {
public string Name = "Super Truck";
public int Tires = 4;
public Truck() { }
public void ResetTruck() {
// Do something here to "reset" the object
}
}
Then at some point, after the Name and Tires properties have been changed, the ResetTruck() method could be called and the properties would be reset back to "Super Truck" and 4, respectively.
What's the best way to reset the properties back to their initial hard-coded defaults?
You can have the initialization in a method instead of inlining with the declaration. Then have the constructor and reset method call the initialization method:
public class Truck {
public string Name;
public int Tires;
public Truck() {
Init();
}
public void ResetTruck() {
Init();
}
private void Init() {
Name = "Super Truck";
Tires = 4;
}
}
Another way is not to have a reset method at all. Just create a new instance.
Reflection is your friend. You could create a helper method to use Activator.CreateInstance() to set the default value of Value types and 'null' for reference types, but why bother when setting null on a PropertyInfo's SetValue will do the same.
Type type = this.GetType();
PropertyInfo[] properties = type.GetProperties();
for (int i = 0; i < properties.Length; ++i)
properties[i].SetValue(this, null); //trick that actually defaults value types too.
To extend this for your purpose, have private members:
//key - property name, value - what you want to assign
Dictionary<string, object> _propertyValues= new Dictionary<string, object>();
List<string> _ignorePropertiesToReset = new List<string>(){"foo", "bar"};
Set the values in your constructor:
public Truck() {
PropertyInfo[] properties = type.GetProperties();
//exclude properties you don't want to reset, put the rest in the dictionary
for (int i = 0; i < properties.Length; ++i){
if (!_ignorePropertiesToReset.Contains(properties[i].Name))
_propertyValues.Add(properties[i].Name, properties[i].GetValue(this));
}
}
Reset them later:
public void Reset() {
PropertyInfo[] properties = type.GetProperties();
for (int i = 0; i < properties.Length; ++i){
//if dictionary has property name, use it to set the property
properties[i].SetValue(this, _propertyValues.ContainsKey(properties[i].Name) ? _propertyValues[properties[i].Name] : null);
}
}
Unless creating the object is really expensive (and Reset isn't for some reason). I see no reason to implement a special reset method. Why don't you just create a new instance with a usable default state.
What is the purpose of reusing the instance?
If you did your initialization in a Reset method you can be good to go:
public class Truck {
public string Name;
public int Tires;
public Truck() {
ResetTruck();
}
public void ResetTruck() {
Name = "Super Truck";
Tires = 4;
}
}
Focusing of separation of concerns (like Brian mentioned in the comments), another alternative would be to add a TruckProperties type (you could even add your default values to its constructor):
public class TruckProperties
{
public string Name
{
get;
set;
}
public int Tires
{
get;
set;
}
public TruckProperties()
{
this.Name = "Super Truck";
this.Tires = 4;
}
public TruckProperties(string name, int tires)
{
this.Name = name;
this.Tires = tires;
}
}
Inside your Truck class, all you would do is manage an instance of the TruckProperties type, and let it do its reset.
public class Truck
{
private TruckProperties properties = new TruckProperties();
public Truck()
{
}
public string Name
{
get
{
return this.properties.Name;
}
set
{
this.properties.Name = value;
}
}
public int Tires
{
get
{
return this.properties.Tires;
}
set
{
this.properties.Tires = value;
}
}
public void ResetTruck()
{
this.properties = new TruckProperties();
}
}
This certainly may be a lot of (unwanted) overhead for such a simple class, but in a bigger/more complex project it could be advantageous.
That's the thing about "best" practices... a lot of times, there's no silver bullet, but only recommendations you must take with skepticism and your best judgement as to what applies to you in a particular case.
I solved a similar problem with reflection. You can use source.GetType().GetProperties() to get a list of all properties which belong to the object.
Although, this is not always a complete solution. If your object implements several interfaces, you will also get all those properties with your reflection call.
So I wrote this simple function which gives us more control of which properties we are interested in resetting.
public static void ClearProperties(object source, List<Type> InterfaceList = null, Type SearchType = null)
{
// Set Interfaces[] array size accordingly. (Will be size of our passed InterfaceList, or 1 if InterfaceList is not passed.)
Type[] Interfaces = new Type[InterfaceList == null ? 1 : InterfaceList.Count];
// If our InterfaceList was not set, get all public properties.
if (InterfaceList == null)
Interfaces[0] = source.GetType();
else // Otherwise, get only the public properties from our passed InterfaceList
for (int i = 0; i < InterfaceList.Count; i++)
Interfaces[i] = source.GetType().GetInterface(InterfaceList[i].Name);
IEnumerable<PropertyInfo> propertyList = Enumerable.Empty<PropertyInfo>();
foreach (Type face in Interfaces)
{
if (face != null)
{
// If our SearchType is null, just get all properties that are not already empty
if (SearchType == null)
propertyList = face.GetProperties().Where(prop => prop != null);
else // Otherwise, get all properties that match our SearchType
propertyList = face.GetProperties().Where(prop => prop.PropertyType == SearchType);
// Reset each property
foreach (var property in propertyList)
{
if (property.CanRead && property.CanWrite)
property.SetValue(source, null, new object[] { });
}
}
else
{
// Throw an error or a warning, depends how strict you want to be I guess.
Debug.Log("Warning: Passed interface does not belong to object.");
//throw new Exception("Warning: Passed interface does not belong to object.");
}
}
}
And it's use:
// Clears all properties in object
ClearProperties(Obj);
// Clears all properties in object from MyInterface1 & MyInterface2
ClearProperties(Obj, new List<Type>(){ typeof(MyInterface1), typeof(MyInterface2)});
// Clears all integer properties in object from MyInterface1 & MyInterface2
ClearProperties(Obj, new List<Type>(){ typeof(MyInterface1), typeof(MyInterface2)}, typeof(int));
// Clears all integer properties in object
ClearProperties(Obj,null,typeof(int));
You'd probably need to save the values off in private fields, so that they can be restored later. Maybe something like this:
public class Truck
{
private static const string defaultName = "Super Truck";
private static const int defaultTires = 4;
// Use properties for public members (not public fields)
public string Name { get; set; }
public int Tires { get; set; }
public Truck()
{
Name = defaultName;
Tires = defaultTires;
}
public void ResetTruck()
{
Name = defaultName;
Tires = defaultTires;
}
}
You're essentially looking for the State Design Pattern
If you want a specific past "state" of your object you can create a particular save point to return every time you want. This also let you have a diferent state to backup for everey instance that you create. If you class has many properties who are in constant change, this could be your solution.
public class Truck
{
private string _Name = "Super truck";
private int _Tires = 4;
public string Name
{
get { return _Name; }
set { _Name = value; }
}
public int Tires
{
get { return _Tires; }
set { _Tires = value; }
}
private Truck SavePoint;
public static Truck CreateWithSavePoint(string Name, int Tires)
{
Truck obj = new Truck();
obj.Name = Name;
obj.Tires = Tires;
obj.Save();
return obj;
}
public Truck() { }
public void Save()
{
SavePoint = (Truck)this.MemberwiseClone();
}
public void ResetTruck()
{
Type type = this.GetType();
PropertyInfo[] properties = type.GetProperties();
for (int i = 0; i < properties.Count(); ++i)
properties[i].SetValue(this, properties[i].GetValue(SavePoint));
}
}
If you aren't using a Code Generator or a Designer that would conflict, another option is to go through C#'s TypeDescriptor stuff, which is similar to Reflection, but meant to add more meta information to a class than Reflection could.
using System.ComponentModel;
public class Truck {
// You can use the DefaultValue Attribute for simple primitive properites
[DefaultValue("Super Truck")]
public string Name { get; set; } = "Super Truck";
// You can use a Reset[PropertyName]() method for more complex properties
public int Tires { get; set; } = 4;
public void ResetTires() => Tires = 4;
public Truck() { }
public void ResetTruck() {
// Iterates through each property and tries to reset it
foreach (PropertyDescriptor prop in TypeDescriptor.GetProperties(GetType())) {
if (prop.CanResetValue(this)) prop.ResetValue(this);
}
}
}
Note that ResetValue will also reset to a shadowed property if one exists. The priority of which option is selected is explained in the docs:
This method determines the value to reset the property to in the following order of precedence:
There is a shadowed property for this property.
There is a DefaultValueAttribute for this property.
There is a "ResetMyProperty" method that you have implemented, where "MyProperty" is the name of the property you pass to it.
You may represent an object state as a struct or record struct and then set the state to the default value in the Reset method like this:
public class Truck {
record struct State(string Name, int Tires);
private static readonly State _defaultState = new("Super Truck", 4);
private State _state = _defaultState;
public string Name => _state.Name;
public int Tires => _state.Tires;
public Truck() {}
public void ResetTruck() => _state = _defaultState;
}
It is probably the fastest way as well.
Also, a record struct will give you the trivial implementations of the ToString, Equals, GetHashCode.