找不到PropertyGrid Browsable实体框架创建的属性，如何找到它？

Question

尝试通过更改Browsable属性来删除或放置属性网格上的项目。

但是除非在对象创建时设置了可浏览，否则我更改Browsable的代码不起作用。现在我可以手动添加可浏览，但是当我对我的实体进行更改（仍在开发项目以便对实体进行大量更改）时，我添加的任何其他属性都会消失。

我试图通过其他两种方式设置[可浏览（真实）]：http://ardalis.com/adding-attributes-to-generated-classes和http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/617ebfca-0f68-4b90-83fd-0da758fadbd0/

两者似乎都实际上正确地设置了Browsable，但是当我通过属性描述符中的属性循环时，它不在那里（我改变）。

  String fieldname = "browsable"; // I also edit "description"
  PropertyDescriptor pd = TypeDescriptor.GetProperties(o.GetType())[propertyName];
  object attrib = null;
  AttributeCollection attribs = pd.Attributes;

  foreach (Attribute a in attribs)
    {
    if (a.GetType() == attributeType)
      {
      attrib = a;
      break;
      }
    }
// The microsoft documentation leads one to believe the following line of code would find the desired attribute,
// negating the need for the more complete foreach statement above.
// However,  it appears to find attribute even when it does not exist. Setting value for "found" attribute 
// will result in random memory being changed, which results in very unpredictable behavior.
// attrib = pd.Attributes[t];

if (attrib != null)
  {
  // locate field that contains value 
  FieldInfo field = attrib.GetType().GetField(fieldName, BindingFlags.NonPublic | BindingFlags.Instance);
  if (field != null)
    {
    if (field.FieldType == value.GetType())
      {
      // set field to desired value
      field.SetValue(attrib, value);
      }
    }
    }
  else
    {
    throw new Exception("Attribute (" + attributeType.Name + ") does not exist for Property(" + propertyName + ")");
    }

所以如果没有找到“可浏览”的话，我会一直得到我抛出的异常 - 但是只有先不在Model.Designer.cs中设置它。

以下是我的Model.Designer.cs的样子。

  /// <summary>
  /// No Metadata Documentation available.
  /// </summary>
  [EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=true)]
  [DataMemberAttribute()]
  [Browsable(false)] // this works, but goes away if change my entity
  public Nullable<global::System.TimeSpan> SignoutAfter
    {
    get
      {
      return _SignoutAfter;
      }
    set
      {
      OnSignoutAfterChanging(value);
      ReportPropertyChanging("SignoutAfter");
      _SignoutAfter = StructuralObject.SetValidValue(value);
      ReportPropertyChanged("SignoutAfter");
      OnSignoutAfterChanged();
      }
    }
  private Nullable<global::System.TimeSpan> _SignoutAfter;
  partial void OnSignoutAfterChanging(Nullable<global::System.TimeSpan> value);
  partial void OnSignoutAfterChanged();

所以我需要一种方法来1.在我编辑它们时添加可浏览实体，这样它总是在编辑t4，但我甚至不知道从哪里开始或2.另一种添加方法或者删除（并编辑）属性（请参阅我可能会根据某些逻辑编辑描述）或3找到我的代码中的漏洞，以便查找和编辑可浏览（描述和显示名称）。

更新我认为上面的第二个链接http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/617ebfca-0f68-4b90-83fd-0da758fadbd0/有很多我需要的东西。将Attribute数组变量添加到类和一些代码以查看是否设置它似乎具有我正在寻找的效果。但是请保持开放以找到更好的答案。

partial class Client : ICustomTypeDescriptor
  {
   public Attribute[] SignOutAttributes; // added this

   #region ICustomTypeDescriptor Members

   ... // see the link for the other code

   public PropertyDescriptorCollection GetProperties (Attribute[] attributes)
      {
      var propsColl = TypeDescriptor.GetProperties (this, attributes, true);
      var props = new List<PropertyDescriptor> ();
      foreach (PropertyDescriptor prop in propsColl)
         {
         String strUPPERCaseName = prop.Name.ToUpper (); // for my thick fingers
         // make sure case values are upper case 
         switch (strUPPERCaseName)
            {
            case "SIGNOUTAFTER":
               if (SignOutAttributes != null)
                  {
                  props.Add(new CustomPropertyDescriptor(prop, SignOutAttributes));
                  }
                else
                  {
                   props.Add (new CustomPropertyDescriptor (prop, new Attribute[]
                     {
                     new CategoryAttribute("Settings"),
                     new DisplayNameAttribute("Signout After"),
                     new BrowsableAttribute(true),
                     new ReadOnlyAttribute(false)
                     }));
                  }
                break;
            default:
               props.Add (prop);
               break;
            }
         }
       return new PropertyDescriptorCollection (props.ToArray ());
       }

在我的代码中，我可以更改属性数组以获得我想要的属性值。

 _client.SignOutAttributes = new Attribute[]
                {
                    new CategoryAttribute ("My Category"),
                    new DisplayNameAttribute("Signout After"),
                    new BrowsableAttribute(true),
                    new ReadOnlyAttribute(false)
                };

我对此并不百分百。我必须为每个Property编写代码。

Answer 1

当您需要动态（在运行时设置）属性时，使用ICustomTypeDescriptor绝对是一个很好的解决方案。这是我一直用于此类属性网格黑客的通用ICustomTypeDescriptor实用程序类，它非常简单易用：

public sealed class DynamicTypeDescriptor: ICustomTypeDescriptor, INotifyPropertyChanged
{
    private Type _type;
    private AttributeCollection _attributes;
    private TypeConverter _typeConverter;
    private Dictionary<Type, object> _editors;
    private EventDescriptor _defaultEvent;
    private PropertyDescriptor _defaultProperty;
    private EventDescriptorCollection _events;

    public event PropertyChangedEventHandler PropertyChanged;

    private DynamicTypeDescriptor()
    {
    }

    public DynamicTypeDescriptor(Type type)
    {
        if (type == null)
            throw new ArgumentNullException("type");

        _type = type;
        _typeConverter = TypeDescriptor.GetConverter(type);
        _defaultEvent = TypeDescriptor.GetDefaultEvent(type);
        _defaultProperty = TypeDescriptor.GetDefaultProperty(type);
        _events = TypeDescriptor.GetEvents(type);

        List<PropertyDescriptor> normalProperties = new List<PropertyDescriptor>();
        OriginalProperties = TypeDescriptor.GetProperties(type);
        foreach (PropertyDescriptor property in OriginalProperties)
        {
            if (!property.IsBrowsable)
                continue;

            normalProperties.Add(property);

        }
        Properties = new PropertyDescriptorCollection(normalProperties.ToArray());

        _attributes = TypeDescriptor.GetAttributes(type);

        _editors = new Dictionary<Type, object>();
        object editor = TypeDescriptor.GetEditor(type, typeof(UITypeEditor));
        if (editor != null)
        {
            _editors.Add(typeof(UITypeEditor), editor);
        }
        editor = TypeDescriptor.GetEditor(type, typeof(ComponentEditor));
        if (editor != null)
        {
            _editors.Add(typeof(ComponentEditor), editor);
        }
        editor = TypeDescriptor.GetEditor(type, typeof(InstanceCreationEditor));
        if (editor != null)
        {
            _editors.Add(typeof(InstanceCreationEditor), editor);
        }
    }

    public T GetPropertyValue<T>(string name, T defaultValue)
    {
        if (name == null)
            throw new ArgumentNullException("name");

        foreach (PropertyDescriptor pd in Properties)
        {
            if (pd.Name == name)
            {
                try
                {
                    return (T)Convert.ChangeType(pd.GetValue(Component), typeof(T));
                }
                catch
                {
                    return defaultValue;
                }
            }
        }
        return defaultValue;
    }

    public void SetPropertyValue(string name, object value)
    {
        if (name == null)
            throw new ArgumentNullException("name");

        foreach (PropertyDescriptor pd in Properties)
        {
            if (pd.Name == name)
            {
                pd.SetValue(Component, value);
                break;
            }
        }
    }

    internal void OnValueChanged(PropertyDescriptor prop)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(prop.Name));
        }
    }

    internal static T GetAttribute<T>(AttributeCollection attributes) where T : Attribute
    {
        if (attributes == null)
            return null;

        foreach (Attribute att in attributes)
        {
            if (typeof(T).IsAssignableFrom(att.GetType()))
                return (T)att;
        }
        return null;
    }

    public sealed class DynamicProperty: PropertyDescriptor, INotifyPropertyChanged
    {
        private readonly Type _type;
        private readonly bool _hasDefaultValue;
        private readonly object _defaultValue;
        private readonly PropertyDescriptor _existing;
        private readonly DynamicTypeDescriptor _descriptor;
        private Dictionary<Type, object> _editors;
        private bool? _readOnly;
        private bool? _browsable;
        private string _displayName;
        private string _description;
        private string _category;
        private List<Attribute> _attributes = new List<Attribute>();

        public event PropertyChangedEventHandler PropertyChanged;

        internal DynamicProperty(DynamicTypeDescriptor descriptor, Type type, object value, string name, Attribute[] attrs)
            : base(name, attrs)
        {
            _descriptor = descriptor;
            _type = type;
            Value = value;
            DefaultValueAttribute def = DynamicTypeDescriptor.GetAttribute<DefaultValueAttribute>(Attributes);
            if (def == null)
            {
                _hasDefaultValue = false;
            }
            else
            {
                _hasDefaultValue = true;
                _defaultValue = def.Value;
            }
            if (attrs != null)
            {
                foreach (Attribute att in attrs)
                {
                    _attributes.Add(att);
                }
            }
        }

        internal static Attribute[] GetAttributes(PropertyDescriptor existing)
        {
            List<Attribute> atts = new List<Attribute>();
            foreach (Attribute a in existing.Attributes)
            {
                atts.Add(a);
            }
            return atts.ToArray();
        }

        internal DynamicProperty(DynamicTypeDescriptor descriptor, PropertyDescriptor existing, object component)
            : this(descriptor, existing.PropertyType, existing.GetValue(component), existing.Name, GetAttributes(existing))
        {
            _existing = existing;
        }

        public void RemoveAttributesOfType<T>() where T : Attribute
        {
            List<Attribute> remove = new List<Attribute>();
            foreach (Attribute att in _attributes)
            {
                if (typeof(T).IsAssignableFrom(att.GetType()))
                {
                    remove.Add(att);
                }
            }

            foreach (Attribute att in remove)
            {
                _attributes.Remove(att);
            }
        }

        public IList<Attribute> AttributesList
        {
            get
            {
                return _attributes;
            }
        }

        public override AttributeCollection Attributes
        {
            get
            {
                return new AttributeCollection(_attributes.ToArray());
            }
        }

        public object Value { get; set; }

        public override bool CanResetValue(object component)
        {
            if (_existing != null)
                return _existing.CanResetValue(component);

            return _hasDefaultValue;
        }

        public override Type ComponentType
        {
            get
            {
                if (_existing != null)
                    return _existing.ComponentType;

                return typeof(object);
            }
        }

        public override object GetValue(object component)
        {
            if (_existing != null)
                return _existing.GetValue(component);

            return Value;
        }

        public override string Category
        {
            get
            {
                if (_category != null)
                    return _category;

                return base.Category;
            }
        }

        public void SetCategory(string category)
        {
            _category = category;
        }

        public override string Description
        {
            get
            {
                if (_description != null)
                    return _description;

                return base.Description;
            }
        }

        public void SetDescription(string description)
        {
            _description = description;
        }

        public override string DisplayName
        {
            get
            {
                if (_displayName != null)
                    return _displayName;

                if (_existing != null)
                    return _existing.DisplayName;

                return base.DisplayName;
            }
        }

        public void SetDisplayName(string displayName)
        {
            _displayName = displayName;
        }

        public override bool IsBrowsable
        {
            get
            {
                if (_browsable.HasValue)
                    return _browsable.Value;

                return base.IsBrowsable;
            }
        }

        public void SetBrowsable(bool browsable)
        {
            _browsable = browsable;
        }

        public override bool IsReadOnly
        {
            get
            {
                if (_readOnly.HasValue)
                    return _readOnly.Value;

                if (_existing != null)
                    return _existing.IsReadOnly;

                ReadOnlyAttribute att = DynamicTypeDescriptor.GetAttribute<ReadOnlyAttribute>(Attributes);
                if (att == null)
                    return false;

                return att.IsReadOnly;
            }
        }

        public void SetIsReadOnly(bool readOnly)
        {
            _readOnly = readOnly;
        }

        public override Type PropertyType
        {
            get
            {
                if (_existing != null)
                    return _existing.PropertyType;

                return _type;
            }
        }

        public override void ResetValue(object component)
        {
            if (_existing != null)
            {
                _existing.ResetValue(component);
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                {
                    handler(this, new PropertyChangedEventArgs(Name));
                }
                _descriptor.OnValueChanged(this);
                return;
            }

            if (CanResetValue(component))
            {
                Value = _defaultValue;
                _descriptor.OnValueChanged(this);
            }
        }

        public override void SetValue(object component, object value)
        {
            if (_existing != null)
            {
                _existing.SetValue(component, value);
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                {
                    handler(this, new PropertyChangedEventArgs(Name));
                }
                _descriptor.OnValueChanged(this);
                return;
            }

            Value = value;
            _descriptor.OnValueChanged(this);
        }

        public override bool ShouldSerializeValue(object component)
        {
            if (_existing != null)
                return _existing.ShouldSerializeValue(component);

            return false;
        }

        public override object GetEditor(Type editorBaseType)
        {
            if (editorBaseType == null)
                throw new ArgumentNullException("editorBaseType");

            if (_editors != null)
            {
                object type;
                if ((_editors.TryGetValue(editorBaseType, out type)) && (type != null))
                    return type;
            }
            return base.GetEditor(editorBaseType);
        }

        public void SetEditor(Type editorBaseType, object obj)
        {
            if (editorBaseType == null)
                throw new ArgumentNullException("editorBaseType");

            if (_editors == null)
            {
                if (obj == null)
                    return;

                _editors = new Dictionary<Type, object>();
            }
            if (obj == null)
            {
                _editors.Remove(editorBaseType);
            }
            else
            {
                _editors[editorBaseType] = obj;
            }
        }
    }

    public PropertyDescriptor AddProperty(Type type, string name, object value, string displayName, string description, string category, bool hasDefaultValue, object defaultValue, bool readOnly)
    {
        return AddProperty(type, name, value, displayName, description, category, hasDefaultValue, defaultValue, readOnly, null);
    }

    public PropertyDescriptor AddProperty(
        Type type,
        string name,
        object value,
        string displayName,
        string description,
        string category,
        bool hasDefaultValue,
        object defaultValue,
        bool readOnly,
        Type uiTypeEditor)
    {
        if (type == null)
            throw new ArgumentNullException("type");

        if (name == null)
            throw new ArgumentNullException("name");

        List<Attribute> atts = new List<Attribute>();
        if (!string.IsNullOrEmpty(displayName))
        {
            atts.Add(new DisplayNameAttribute(displayName));
        }

        if (!string.IsNullOrEmpty(description))
        {
            atts.Add(new DescriptionAttribute(description));
        }

        if (!string.IsNullOrEmpty(category))
        {
            atts.Add(new CategoryAttribute(category));
        }

        if (hasDefaultValue)
        {
            atts.Add(new DefaultValueAttribute(defaultValue));
        }

        if (uiTypeEditor != null)
        {
            atts.Add(new EditorAttribute(uiTypeEditor, typeof(UITypeEditor)));
        }

        if (readOnly)
        {
            atts.Add(new ReadOnlyAttribute(true));
        }

        DynamicProperty property = new DynamicProperty(this, type, value, name, atts.ToArray());
        AddProperty(property);
        return property;
    }

    public void RemoveProperty(string name)
    {
        if (name == null)
            throw new ArgumentNullException("name");

        List<PropertyDescriptor> remove = new List<PropertyDescriptor>();
        foreach (PropertyDescriptor pd in Properties)
        {
            if (pd.Name == name)
            {
                remove.Add(pd);
            }
        }

        foreach (PropertyDescriptor pd in remove)
        {
            Properties.Remove(pd);
        }
    }

    public void AddProperty(PropertyDescriptor property)
    {
        if (property == null)
            throw new ArgumentNullException("property");

        Properties.Add(property);
    }

    public override string ToString()
    {
        return base.ToString() + " (" + Component + ")";
    }

    public PropertyDescriptorCollection OriginalProperties { get; private set; }
    public PropertyDescriptorCollection Properties { get; private set; }

    public DynamicTypeDescriptor FromComponent(object component)
    {
        if (component == null)
            throw new ArgumentNullException("component");

        if (!_type.IsAssignableFrom(component.GetType()))
            throw new ArgumentException(null, "component");

        DynamicTypeDescriptor desc = new DynamicTypeDescriptor();
        desc._type = _type;
        desc.Component = component;

        // shallow copy on purpose
        desc._typeConverter = _typeConverter;
        desc._editors = _editors;
        desc._defaultEvent = _defaultEvent;
        desc._defaultProperty = _defaultProperty;
        desc._attributes = _attributes;
        desc._events = _events;
        desc.OriginalProperties = OriginalProperties;

        // track values
        List<PropertyDescriptor> properties = new List<PropertyDescriptor>();
        foreach (PropertyDescriptor pd in Properties)
        {
            DynamicProperty ap = new DynamicProperty(desc, pd, component);
            properties.Add(ap);
        }

        desc.Properties = new PropertyDescriptorCollection(properties.ToArray());
        return desc;
    }

    public object Component { get; private set; }
    public string ClassName { get; set; }
    public string ComponentName { get; set; }

    AttributeCollection ICustomTypeDescriptor.GetAttributes()
    {
        return _attributes;
    }

    string ICustomTypeDescriptor.GetClassName()
    {
        if (ClassName != null)
            return ClassName;

        if (Component != null)
            return Component.GetType().Name;

        if (_type != null)
            return _type.Name;

        return null;
    }

    string ICustomTypeDescriptor.GetComponentName()
    {
        if (ComponentName != null)
            return ComponentName;

        return Component != null ? Component.ToString() : null;
    }

    TypeConverter ICustomTypeDescriptor.GetConverter()
    {
        return _typeConverter;
    }

    EventDescriptor ICustomTypeDescriptor.GetDefaultEvent()
    {
        return _defaultEvent;
    }

    PropertyDescriptor ICustomTypeDescriptor.GetDefaultProperty()
    {
        return _defaultProperty;
    }

    object ICustomTypeDescriptor.GetEditor(Type editorBaseType)
    {
        object editor;
        if (_editors.TryGetValue(editorBaseType, out editor))
            return editor;

        return null;
    }

    EventDescriptorCollection ICustomTypeDescriptor.GetEvents(Attribute[] attributes)
    {
        return _events;
    }

    EventDescriptorCollection ICustomTypeDescriptor.GetEvents()
    {
        return _events;
    }

    PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties(Attribute[] attributes)
    {
        return Properties;
    }

    PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
    {
        return Properties;
    }

    object ICustomTypeDescriptor.GetPropertyOwner(PropertyDescriptor pd)
    {
        return Component;
    }
}