使用自定义C#配置时出现未识别元素异常

Question

我在 .NET 3.5 的 Windows Service 的 App.config 中有以下的配置：

<configSections>
    <section name="ConfigurationServiceSection" type="SomeApp.Framework.Configuration.ConfigurationServiceSection, SomeApp.Framework"/>
</configSections>

<ConfigurationServiceSection configSource="ConfigSections\configurationServiceSection.config" />

我在configurationServiceSection.config文件中找到了以下内容:

<ConfigurationServiceSection>
    <ConfigurationServices>
        <ConfigurationService name="LocalConfig" host="localhost" port="40001" location="LON"/>
    </ConfigurationServices>
</ConfigurationServiceSection>

以下是代码：

using System.Configuration;

namespace SomeApp.Framework.Configuration
{
    public sealed class ConfigurationServiceSection : ConfigurationSection
    {
        [ConfigurationProperty("ConfigurationServices", IsDefaultCollection = true, IsRequired = true)]
        [ConfigurationCollection(typeof(ConfigurationServices))]
        public ConfigurationServices ConfigurationServices
        {
            get
            {
                return (ConfigurationServices)base["ConfigurationServices"];
            }
        }
    }

    public sealed class ConfigurationServices : ConfigurationElementCollection
    {
        protected override ConfigurationElement CreateNewElement()
        {
            return new ConfigurationService();
        }

        protected override object GetElementKey(ConfigurationElement element)
        {
            ConfigurationService configService = (ConfigurationService) element;
            return configService.Name;
        }
    }

    public sealed class ConfigurationService : ConfigurationElement
    {
        /// <summary>
        /// name
        /// </summary>
        [ConfigurationProperty("name", IsKey = true, IsRequired = true)]
        public string Name
        {
            get { return (string)this["name"]; }
            set { this["name"] = value; }
        }

        /// <summary>
        /// host
        /// </summary>
        [ConfigurationProperty("host", IsKey = false, IsRequired = true)]
        public string Host
        {
            get { return (string)this["host"]; }
            set { this["host"] = value; }
        }

        /// <summary>
        /// port
        /// </summary>
        [ConfigurationProperty("port", IsKey = false, IsRequired = true)]
        public string Port
        {
            get { return (string)this["port"]; }
            set { this["port"] = value; }
        }

        /// <summary>
        /// location
        /// </summary>
        [ConfigurationProperty("location", IsKey = false, IsRequired = true)]
        public string Location
        {
            get { return (string)this["location"]; }
            set { this["location"] = value; }
        }
    }
}

当我尝试使用以下内容访问配置文件时：

var configurationServiceSection = (ConfigurationServiceSection)configuration.GetSection("ConfigurationServiceSection");

我收到了这个异常：

Unrecognized element 'ConfigurationService'. (C:\Code\branches\ConfigurationService\SomeApp\Src\ConfigService\SomeApp.ConfigService.WindowsService\bin\Debug\ConfigSections\configurationServiceSection.config line 3)

我觉得一切看起来都没问题了？

有什么想法吗？谢谢。

- Mike

---

参见：如何解决“未识别的元素'elementName'”。 - Joshua Drake

Answer 1

好的，我已经弄清楚了：

我像下面这样向ConfigurationServiceSection类添加了“AddItemName”：

public sealed class ConfigurationServiceSection : ConfigurationSection
{
    [ConfigurationProperty("ConfigurationServices", IsDefaultCollection = true, IsRequired = true)]
    [ConfigurationCollection(typeof(ConfigurationServices), AddItemName = "ConfigurationService")]
    public ConfigurationServices ConfigurationServices
    {
        get
        {
            return (ConfigurationServices)base["ConfigurationServices"];
        }
    }
}

另一种选择是覆盖 CollectionType 和 ElementName 属性，如下所示：

public override ConfigurationElementCollectionType CollectionType
{
    get { return ConfigurationElementCollectionType.BasicMap; }
}

protected override string ElementName
{
    get { return "ConfigurationService"; }
}

- Mike

---

对我来说，需要更改的是“return ConfigurationElementCollectionType.BasicMap;”为“return ConfigurationElementCollectionType.AddRemoveClearMap;”，但这篇文章帮助我找到了答案！ - Dib

这个 AddItemName 解决方案非常明显。相当直观。相当易于发现。设计配置框架，使 xml 结构类似于您的对象模型，直到您尝试向集合添加项目时，此时使用 xml 元素 <add /> 而不是对象类型/名称。这将让他们猜测。大约 6 小时左右。 - user74754

覆盖集合类中的ElementName是使其对我起作用的关键部分。设置AddItemName是不够的。不用说，这在MSDN示例中是缺失的。 - Lee D