Sections must only appear once per config file! why?

问题

I'm getting the following exeption: "Sections must only appear once per config file. See the help topic for exceptions. "

my configuration file look like this:

<configSections>
    <sectionGroup name="point.System">
        <section name="singleInstanceCache"
            type="xyz.Point.System.Configuration.SingleInstanceCache, Point.System" />
    </sectionGroup>
    <sectionGroup name="point.Services">
        <sectionGroup name="xServices" type="xyz.Point.Messaging.PointServiceConfiguration.PointServices, Barcap.FIA.Point.Messaging">
            <section name="xService"
                type="xyz.Point.Messaging.PointServiceConfiguration.PointService, Barcap.FIA.Point.Messaging" />
        </sectionGroup>
    </sectionGroup>
</configSections>

<point.Services>
    <xServices>
        <xService name="Service1" type="IService" >
            <endpoints>
                <endpoint aliasName="incoming" endpointName="Subscriber"/>
                <endpoint aliasName="outgoing" endpointName="Publisher"/>
            </endpoints>
        </xService>
        <xService name="BlobService" type="IPortfolioService" >
            <endpoints>
                <endpoint aliasName="incoming" endpointName="Subscriber"/>
                <endpoint aliasName="outgoing" endpointName="Publisher"/>
            </endpoints>
        </xService>
    </xServices>
</point.Services>

here is the code where i load it:

public class PointServices : ConfigurationSection
{
    public static PointServices Get()
    {
        var t = (PointServices)ConfigurationManager.GetSection("point.Services/xServices");

        return null;
    }

    //<summary>
    //Declares a collection element represented in the following configuration sub-section
    //<singleInstances> <add .../> </singleInstances> 
    //</summary>
    [ConfigurationProperty("xServices", IsDefaultCollection = true)]
    [ConfigurationCollection(typeof(PointServices), AddItemName = "xService")]
    public PointServicesCollection Services
    {
        get { return (PointServicesCollection) base["xServices"]; }
    }
}

public class PointService : ConfigurationElement
{
    [ConfigurationProperty("name",IsRequired = true)]
    public string Name
    {
        get { return this["name"].ToString(); }
    }

    [ConfigurationProperty("type", IsRequired = true)]
    public string Type
    {
        get { return this["type"].ToString(); }
    }

    [ConfigurationProperty("endpoints", IsRequired = false)]
    [ConfigurationCollection(typeof(EndpointAliasCollection), AddItemName = "endpoint")]
    public EndpointAliasCollection Endpoints
    {
        get { return (EndpointAliasCollection)this["endpoints"]; }
    }
}

if you have any idea why i'm getting this error, that would be helpful.

Thanks

回答1:

You are trying to use a section group as a collection, and sections as items in the collection, which is not what they are intended for, hence the error.

Basically you only need to define point.Services as a section, as it does not need to contain any other sections, then define a collection property to contain configuration elements. You can update the code as follows:

Config:

<configSections>
    <section name="point.Services" 
        type="xyz.Point.Messaging.PointServiceConfiguration.PointServices, Barcap.FIA.Point.Messaging" />
</configSections>

<point.Services>
    <xServices>
        <xService name="Service1" type="IService" >
            <endpoints>
                <endpoint aliasName="incoming" endpointName="Subscriber"/>
                <endpoint aliasName="outgoing" endpointName="Publisher"/>
            </endpoints>
        </xService>
        <xService name="BlobService" type="IPortfolioService" >
            <endpoints>
                <endpoint aliasName="incoming" endpointName="Subscriber"/>
                <endpoint aliasName="outgoing" endpointName="Publisher"/>
            </endpoints>
        </xService>
    </xServices>
</point.Services>

Then the code is:

public class PointServices : ConfigurationSection
{
    public static PointServices Get()
    {
        return (PointServices) ConfigurationManager.GetSection("point.Services");
    }

    [ConfigurationProperty("xServices", IsDefaultCollection = true)]
    [ConfigurationCollection(typeof(PointService), AddItemName = "xService")]
    public PointServicesCollection Services
    {
        get { return (PointServicesCollection) base["xServices"]; }
    }
}

public class PointService : ConfigurationElement
{
    [ConfigurationProperty("name", IsRequired = true)]
    public string Name
    {
        get { return this["name"].ToString(); }
    }

    [ConfigurationProperty("type", IsRequired = true)]
    public string Type
    {
        get { return this["type"].ToString(); }
    }

    [ConfigurationProperty("endpoints", IsRequired = false)]
    [ConfigurationCollection(typeof(EndpointAlias), AddItemName = "endpoint")]
    public EndpointAliasCollection Endpoints
    {
        get { return (EndpointAliasCollection) this["endpoints"]; }
    }
}

To break it down:

• PointServices is a configuration section that maps to <point.Services> section, so the static Get() method reflects this
• PointServices defines a collection property Services which is a PointServiceCollection where the item type is PointService (NOT PointServices) and is mapped to the element name xService
• PointService elements are elements and not sections, again note that the collection property attribute defines the item type, not the container type

Hope that helps.

回答2:

Where is Point.System in the config file? It might just be complaining because 0 != 1 (to the computer)

来源：https://stackoverflow.com/questions/1768362/sections-must-only-appear-once-per-config-file-why