c# - 如何将 TypeConverter 与 ConfigurationSection 一起使用？

Question

所以我有一个配置如下的 ConfigurationSection/ConfigurationElementCollection:

<mimeFormats>
    <add mimeFormat="text/html" />
</mimeFormats>

下面是我处理 mimeFormats 的方式:

 public class MimeFormatElement: ConfigurationElement
{
    #region Constructors
    /// <summary>
    /// Predefines the valid properties and prepares
    /// the property collection.
    /// </summary>
    static MimeFormatElement()
    {
        // Predefine properties here
        _mimeFormat = new ConfigurationProperty(
            "mimeFormat",
            typeof(MimeFormat),
            "*/*",
            ConfigurationPropertyOptions.IsRequired
        );
    }
    private static ConfigurationProperty _mimeFormat;
    private static ConfigurationPropertyCollection _properties;

    [ConfigurationProperty("mimeFormat", IsRequired = true)]
    public MimeFormat MimeFormat
    {
        get { return (MimeFormat)base[_mimeFormat]; }
    }
}

public class MimeFormat
{
    public string Format
    {
        get
        {
            return Type + "/" + SubType;
        }
    }
    public string Type;
    public string SubType;

    public MimeFormat(string mimeFormatStr)
    {
        var parts = mimeFormatStr.Split('/');
        if (parts.Length != 2)
        {
            throw new Exception("Invalid MimeFormat");
        }

        Type = parts[0];
        SubType = parts[1];
    }
}

显然我需要一个 TypeConverter 来实际做一些事情(而不是这个空壳):

public class MimeFormatConverter : TypeConverter
{
    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
    {
        throw new NotImplementedException();
    }
    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        throw new NotImplementedException();
    }

    public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
    {
        throw new NotImplementedException();
    }
    public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
    {
        throw new NotImplementedException();
    }
}

如何设置一个 TypeConverter 以允许从/到字符串的类型转换？我已尝试使用 MSDN 示例，但我不断收到错误消息:

TypeConverter cannot convert from System.String.

从本质上讲，如何设置它才能使其与 ConfigurationSection 试图做的任何事情一起工作？

Answer 1

您可以将 TypeConverterAttribute 放在属性上以告诉序列化程序如何处理它。

[TypeConverter(typeof(MimeFormatConverter))]
[ConfigurationProperty("mimeFormat", IsRequired = true)]
public MimeFormat MimeFormat
{
    get { return (MimeFormat)base[_mimeFormat]; }
}