Custom app.config list producing error on ApplicationConfiguration.GetSection()

Question

Background: Trying to implement a list in app.config as per these examples:

Goal: I am looking to resolve this error and have this working.

Error:

Unrecognized element 'lookupMapping'. (C: ...line 75)

Error produced on this line while debugging through:

LookupMappingsConfigSection section = (LookupMappingsConfigSection)config.Sections["lookupMappings"];

app.config snippets:

<configuration>
  <configSections>
    <section name="lookupMappings" type="System.Configuration.AppSettingsSection, System.Configuration, Version=4.0.30319.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/> 
  </configSections>
  <lookupMappings>
    <lookupMapping name="One" lookupName="foo" />
    <lookupMapping name="Two" lookupName="foo" />
    <lookupMapping name="Three" lookupName="foo" />
    <lookupMapping name="Four" lookupName="foo" />
  </lookupMappings> 
</configuration>

Classes:

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

    [ConfigurationProperty("lookupName", IsRequired = true)]
    public string LookupName
    {
        get { return (string)base["lookupName"]; }
        set { base["lookupName"] = value; }
    }
}

public class LookupMappingsConfigSection: ConfigurationSection
{
    [ConfigurationProperty("lookupMappings", IsDefaultCollection = true, IsRequired = true)]
    [ConfigurationCollection(typeof(LookupMappingsConfigCollection), AddItemName = "lookupMapping")]
    public LookupMappingsConfigCollection Instances
    {
        get { return (LookupMappingsConfigCollection) this[""]; }
        set { this[""] = value; }
    }
}

public class LookupMappingsConfigCollection : ConfigurationElementCollection
{
    protected override ConfigurationElement CreateNewElement()
    {
        return new LookupMappingsInstanceElement();
    }

    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((LookupMappingsInstanceElement) element).Name;
    }

    public LookupMappingsInstanceElement this[int idx]
    {
        get { return (LookupMappingsInstanceElement)BaseGet(idx); }
    }

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

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

Implementation c#:

Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
LookupMappingsConfigSection section = (LookupMappingsConfigSection)config.Sections["lookupMappings"]; // <--ERROR ON THIS LINE
LookupMappingsInstanceElement entry1 = section.Instances[0];
LookupMappingsInstanceElement entry2 = section.Instances[1];

Thanks, now I'm getting "Unrecognized element 'lookupMapping'". Note that I changed the Configuration section class as follows to get around a null exception. get { return (LookupMappingsConfigCollection)this["lookupMappings"]; } set { this["lookupMappings"] = value; } This is where I get the new message: LookupMappingsConfigSection section = (LookupMappingsConfigSection)config.Sections["lookupMappings"]; — John, Jul 04 '12 at 04:12

score 2 · Answer 1 · answered Jul 04 '12 at 06:54

OK. I got it going, as per the posts my namespace and assembly were incorrect in the app.config sections area. I also had to add an additional grouping in my app.config for it to play nice. Here's my end product in case it helps someone else..

App.config

<configuration>
  <configSection>
    <section name="LookupMappingsSection" type="your.namespace.LookupMappingsConfigSection, your.assembly"/>
  </configSections>
  <LookupMappingsSection>
    <LookupMappings>
      <add name="One" lookupName="foo" />
      <add name="Two" lookupName="foo" />
      <add name="Three" lookupName="foo" />
      <add name="Four" lookupName="foo" />
    </LookupMappings>
  </LookupMappingsSection>
</configuration>

c# Classes

public class LookupMappingsConfigSection: ConfigurationSection
{
    [ConfigurationProperty("LookupMappings")]
    public LookupMappingsConfigCollection LookupMappings
    {
        get { return ((LookupMappingsConfigCollection)(base["LookupMappings"])); }
    }
}

[ConfigurationCollection(typeof(LookupMappingElement))]
public class LookupMappingsConfigCollection : ConfigurationElementCollection
{
    protected override ConfigurationElement CreateNewElement()
    {
        return new LookupMappingElement();
    }

    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((LookupMappingElement) element).Name;
    }

    public LookupMappingElement this[int idx]
    {
        get { return (LookupMappingElement)BaseGet(idx); }
    }

}

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

    [ConfigurationProperty("lookupName", DefaultValue = "", IsKey = false, IsRequired = false)]
    public string LookupName
    {
        get { return (string)this["lookupName"]; }
        set { base["lookupName"] = value; }
    }
}

//Get the lookup entries
LookupMappingsConfigSection section = (LookupMappingsConfigSection)ConfigurationManager.GetSection("LookupMappingsSection");
foreach(LookupMappingElement lookupMapping in section.LookupMappings)
{ 
    //Do something 
}

score 1 · Answer 2 · answered Jul 03 '12 at 07:10

1

What is the namespace of your custom configuration section?

I see from the config file that you wrote:

type="System.Configuration.AppSettingsSection, System.Configuration, Version=4.0.30319.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"

Shouldn't this be something like:

type="your.namespace.LookupMappingsConfigSection, your.assembly" ?

For custom configuration sections you can also check out Configuration Section Designer

answered Jul 03 '12 at 07:10

vukashin

86
6

Thanks, now I'm getting "Unrecognized element 'lookupMapping'". – John Jul 04 '12 at 03:23

score 1 · Answer 3 · answered Jul 03 '12 at 07:11

The config section definition is not valid. It should point to the fully qualified name where LookupMappingsConfigSection is implemented.

<configuration>
  <configSections>
    <section name="lookupMappings" type="MyAssembly.Namespace.LookupMappingsConfigSection, MyAssembly"/> 
  </configSections>
  <lookupMappings>
    <lookupMapping name="One" lookupName="foo" />
    <lookupMapping name="Two" lookupName="foo" />
    <lookupMapping name="Three" lookupName="foo" />
    <lookupMapping name="Four" lookupName="foo" />
  </lookupMappings> 
</configuration>

score 1 · Accepted Answer · answered Jul 03 '12 at 07:17

The main issue is that you're attempting to load your lookupMappings section as a standard AppSettingsSection. Change your configuration file to:

<configuration>
  <configSections>
    <section name="lookupMappings" type="Fully.Qualified.Type.Of.LookupMappingsConfigSectionType, Name.Of.Assembly.Containing.LookupMappingsConfigSectionType"/> 
  </configSections>
  <lookupMappings>
    <lookupMapping name="One" lookupName="foo" />
    <lookupMapping name="Two" lookupName="foo" />
    <lookupMapping name="Three" lookupName="foo" />
    <lookupMapping name="Four" lookupName="foo" />
  </lookupMappings> 
</configuration>

NOTE: You'll need to replace Fully.Qualified.Type.Of.LookupMappingsConfigSectionType and Name.Of.Assembly.Containing.LookupMappingsConfigSectionType with the appropriate type and assembly names.

Custom app.config list producing error on ApplicationConfiguration.GetSection()

4 Answers4