找不到String的构造方法 [英] Constructor not found for String

问题描述

如果我在属性网格中有一个包含 List< string []> 或 Dictionary< string，string []> (使用 GenericDictionaryEditor )，当我单击属性旁边的详细信息并单击添加时，弹出消息，提示找不到任何构造函数(用于列表)或找不到无参数构造函数(用于字典).我真的不了解编辑器或属性网格，将不胜感激.

If I have an object in a property grid containing a List<string[]> or Dictionary<string,string[]>(using GenericDictionaryEditor), when I click on the detail beside the property and click add, a message pops up saying that no constructor can be found (for the list) or no parameterless constructor found (for the dictionary). I don't understand editors or the property grid really, and any help would be appreciated.

[DataMember(Name="FolderPaths")]
[ReadOnly(false)]
[Description("List of folder paths")]
[Editor(typeof(Wexman.Design.GenericDictionaryEditor<string, string[]>), typeof(UITypeEditor))]
[Wexman.Design.GenericDictionaryEditor(Title="Folder Paths")]
public Dictionary<string, string[]> FolderPaths { get; set; }

有人说找不到System.string []的构造函数.

This one says constructor not found for System.string[].

[DataMember(Name="FolderPaths")]
[ReadOnly(false)]
[Description("List of folder paths")]
public List<string[]> FolderPaths { get; set; }

推荐答案

一种解决方案是注册

One solution is to register a TypeDescriptionProvider for the string[] type. Here is the sample code (you need to register this at the beginning of your program, before displaying any property grid):

...
TypeDescriptor.AddProvider(new StringArrayDescriptionProvider(), typeof(string[]));
...

这是 StringArrayDescriptionProvider 代码:

public class StringArrayDescriptionProvider : TypeDescriptionProvider
{
    private static TypeDescriptionProvider _baseProvider;

    static StringArrayDescriptionProvider()
    {
       // get default metadata
        _baseProvider = TypeDescriptor.GetProvider(typeof(string[]));
    }

    public override object CreateInstance(IServiceProvider provider, Type objectType, Type[] argTypes, object[] args)
    {
        // this is were we define create the instance
        // NB: .NET could do this IMHO...
        return Array.CreateInstance(typeof(string), 0);
    }

    public override IDictionary GetCache(object instance)
    {
        return _baseProvider.GetCache(instance);
    }

    public override ICustomTypeDescriptor GetExtendedTypeDescriptor(object instance)
    {
        return _baseProvider.GetExtendedTypeDescriptor(instance);
    }

    public override string GetFullComponentName(object component)
    {
        return _baseProvider.GetFullComponentName(component);
    }

    public override Type GetReflectionType(Type objectType, object instance)
    {
        return _baseProvider.GetReflectionType(objectType, instance);
    }

    public override Type GetRuntimeType(Type reflectionType)
    {
        return _baseProvider.GetRuntimeType(reflectionType);
    }

    public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance)
    {
        return _baseProvider.GetTypeDescriptor(objectType, instance);
    }

    public override bool IsSupportedType(Type type)
    {
        return _baseProvider.IsSupportedType(type);
    }
}

这是它的外观:

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