Question

G'da给大家，

几个小时以来，我一直试图想出如何从app.config文件中读取设置：

<?xml version="1.0"?>
<configuration>

  <configSections>
    <section name="Databases" type="McFix.DatabaseSection, McFix"/>
  </configSections>

  <Databases>
    <Database name="database">
      <Tables>
        <Table name="be_sessions">
          <Columns>
            <Column name="sess_id">
            </Column>
          </Columns>
        </Table>
      </Tables>
    </Database>
  </Databases>

  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
  </startup>
</configuration>

自定义处理程序类的代码是here，也复制如下：

public class DatabaseSection : ConfigurationSection
{
    [ConfigurationProperty("Databases", IsDefaultCollection = false)]
    public DatabaseInstanceCollection Databases
    {
        get { return (DatabaseInstanceCollection)this["Databases"]; }
        set { this[""] = value; }
    }
}
[ConfigurationCollection(typeof(DatabaseElement), AddItemName = "add", CollectionType = ConfigurationElementCollectionType.BasicMap )]
public class DatabaseInstanceCollection : ConfigurationElementCollection
{
    protected override ConfigurationElement CreateNewElement()
    {
        return new DatabaseElement();
    }
    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((DatabaseElement)element).Name;
    }
}
public class DatabaseElement : ConfigurationElement
{
    [ConfigurationProperty("name", IsKey = true, IsRequired = true)]
    public string Name
    {
        get { return (string)base["name"]; }
        set { base["name"] = value; }
    }
}

public class TableSection : ConfigurationSection
{
    [ConfigurationProperty("Tables", IsDefaultCollection = true)]
    public TableInstanceCollection Tables
    {
        get { return (TableInstanceCollection)this["Tables"]; }
        set { this[""] = value; }
    }
}

[ConfigurationCollection(typeof(TableElement), AddItemName = "Table", CollectionType = ConfigurationElementCollectionType.BasicMap)]
public class TableInstanceCollection : ConfigurationElementCollection
{
    protected override ConfigurationElement CreateNewElement()
    {
        return new TableElement();
    }
    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((TableElement)element).Name;
    }
}

public class TableElement : ConfigurationElement
{
    [ConfigurationProperty("name", IsKey = true, IsRequired = true)]
    public string Name
    {
        get { return (string)base["name"]; }
        set { base["name"] = value; }
    }
}

public class ColumnSection : ConfigurationSection
{
    [ConfigurationProperty("Columns", IsDefaultCollection = true)]
    public ColumnInstanceCollection Columns
    {
        get { return (ColumnInstanceCollection)this["Columns"]; }
        set { this[""] = value; }
    }
}

[ConfigurationCollection(typeof(ColumnElement), AddItemName = "Column", CollectionType = ConfigurationElementCollectionType.BasicMap)]
public class ColumnInstanceCollection : ConfigurationElementCollection
{
    protected override ConfigurationElement CreateNewElement()
    {
        return new ColumnElement();
    }
    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((ColumnElement)element).Name;
    }
}

public class ColumnElement : ConfigurationElement
{
    [ConfigurationProperty("name", IsKey = true, IsRequired = true)]
    public string Name
    {
        get { return (string)base["name"]; }
        set { base["name"] = value; }
    }
}

问题是当我尝试通过GetSection方法获取“数据库”部分时：

Configuration Config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
DatabaseSection DbConfig = Config.GetSection("Databases") as DatabaseSection;

程序抛出一个ConfigurationErrorsException，报告“无法识别的元素'数据库'”，虽然它是在通过DatabaseSection的get方法后执行的，即使我将DatabaseInstanceCollection的AddItemName定义为“Database”。我错过了一些属性，它会让底层代码正确读取app.config吗？

Answer 1

强制性链接：

粗略地看一下你的问题似乎就在这一行：

[ConfigurationCollection(typeof(DatabaseElement), AddItemName = "add", CollectionType = ConfigurationElementCollectionType.BasicMap )]

这表明.config文件应如下所示：

<Databases>
    <add><!-- Database goes here --></add>
</Databases>

即。您的Databases元素期待一个“添加”子元素，表示要将一个项目添加到集合中。

您应该尝试将AddItemName属性从“添加”更改为“数据库”：

[ConfigurationCollection(typeof(DatabaseElement), AddItemName = "Database", CollectionType = ConfigurationElementCollectionType.BasicMap )]

（我没有机会测试这个，可能还有其他问题）

Answer 2

你是对的，Kragen，我必须删除Table / ColumnSection并将Table / ColumnInstanceCollection添加到Database / TableElement。 DatabaseSection'数据库属性必须像：

[ConfigurationProperty("", IsDefaultCollection = true)]
        public DatabaseInstanceCollection Databases
        {
            get { return (DatabaseInstanceCollection)this[""]; }
        }

app.config中的嵌套自定义元素（C＃）

2 个答案: