问题
gleanings from a variety of sources (including stackOverlflow), however when I come to use it, I get the following error message
"The Configuration property 'deviceconfig' may not be derived from ConfigurationSection."
I have been struggling with this for the better part of a day now, and am no nearer a solution, so any help in the matter would be greatly appreciated. I am a newbie in implementing custom config sections so please treat me gently :-)
The app.config file looks like this:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="deviceconfig" type="CNIMonitor.Core.CustomConfig.DeviceConfig,Core"/>
</configSections>
<system.diagnostics>
<sources>
<!-- This section defines the logging configuration for My.Application.Log -->
<source name="DefaultSource" switchName="DefaultSwitch">
<listeners>
<add name="FileLog"/>
<!-- Uncomment the below section to write to the Application Event Log -->
<!--<add name="EventLog"/>-->
</listeners>
</source>
</sources>
<switches>
<add name="DefaultSwitch" value="Information" />
</switches>
<sharedListeners>
<add name="FileLog"
type="Microsoft.VisualBasic.Logging.FileLogTraceListener, Microsoft.VisualBasic, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL"
initializeData="FileLogWriter"/>
<!-- Uncomment the below section and replace APPLICATION_NAME with the name of your application to write to the Application Event Log -->
<!--<add name="EventLog" type="System.Diagnostics.EventLogTraceListener" initializeData="APPLICATION_NAME"/> -->
</sharedListeners>
</system.diagnostics>
<deviceconfig>
<devices>
<device deviceid = "1"
name = "localhost"
ipaddress="127.0.0.1"
port="10000"
status="not listening"
message="no message"
/>
<device deviceid ="2"
name ="2nd localhost"
ipaddress="127.0.0.1"
port="20000"
status="not listening"
message="no message"
/>
</devices>
</deviceconfig>
The Custom Section Handler code as follows:
Imports System.Configuration
Namespace CNIMonitor.Core.CustomConfig
Public Class DeviceConfig
Inherits ConfigurationSection
<ConfigurationProperty("deviceconfig")> _
Public ReadOnly Property DeviceConfig() As DeviceConfig
Get
Return CType(MyBase.Item("deviceconfig"), DeviceConfig)
End Get
End Property
End Class
<ConfigurationCollectionAttribute(GetType(Device))> _
Public Class Devices
Inherits ConfigurationElementCollection
Protected Overrides Function CreateNewElement() As ConfigurationElement
Return New Device
End Function
Protected Overrides Function GetElementKey _
(ByVal element As ConfigurationElement) As Object
Return CType(element, Device).DeviceID
End Function
Public Sub Add(ByVal element As Device)
Me.BaseAdd(element)
End Sub
End Class
Public Class Device
Inherits ConfigurationElement
<ConfigurationProperty("deviceid", DefaultValue:="", IsKey:=True, IsRequired:=True)> _
Public Property DeviceID() As String
Get
Return CType(MyBase.Item("deviceid"), String)
End Get
Set(ByVal value As String)
MyBase.Item("deviceid") = value
End Set
End Property
<ConfigurationProperty("hostname", DefaultValue:="", IsKey:=True, IsRequired:=False)> _
Public Property HostName() As String
Get
Return CType(MyBase.Item("RegisteredDate"), String)
End Get
Set(ByVal value As String)
MyBase.Item("RegisteredDate") = value
End Set
End Property
<ConfigurationProperty("ipaddress", DefaultValue:="", IsKey:=True, IsRequired:=False)> _
Public Property IpAddress() As String
Get
Return CType(MyBase.Item("ipaddress"), String)
End Get
Set(ByVal value As String)
MyBase.Item("ipaddress") = value
End Set
End Property
<ConfigurationProperty("port", DefaultValue:="", IsKey:=True, IsRequired:=False)> _
Public Property Port() As String
Get
Return CType(MyBase.Item("port"), String)
End Get
Set(ByVal value As String)
MyBase.Item("port") = value
End Set
End Property
<ConfigurationProperty("status", DefaultValue:="", IsKey:=False, IsRequired:=False)> _
Public Property Status() As String
Get
Return CType(MyBase.Item("status"), String)
End Get
Set(ByVal value As String)
MyBase.Item("status") = value
End Set
End Property
<ConfigurationProperty("message", DefaultValue:="", IsKey:=False, IsRequired:=False)> _
Public Property Message() As String
Get
Return CType(MyBase.Item("message"), String)
End Get
Set(ByVal value As String)
MyBase.Item("message") = value
End Set
End Property
End Class
End Namespace
回答1:
The DeviceConfig property is not needed at the top level. What you do need to do is add a property for your ConfigurationElementCollection devices. I would also rename your Devices class something a little less ambiguous, say, DeviceElementCollection. Try this:
Public Class DeviceConfig
Inherits ConfigurationSection
<ConfigurationProperty("Devices")> _
Public ReadOnly Property Devices() As DeviceElementCollection
Get
Return CType(Me("Devices"), DeviceElementCollection)
End Get
End Property
End Class
Then, in your definition for DeviceElementCollection, you may have problems if you don't add the following:
Public Overrides ReadOnly Property CollectionType() As System.Configuration.ConfigurationElementCollectionType
Get
Return ConfigurationElementCollectionType.BasicMap
End Get
End Property
Protected Overrides ReadOnly Property ElementName() As String
Get
Return "Device"
End Get
End Property
I wrote up a pretty long answer to a similar question (sorry, in C#) here.
Update - how to use in code
Dim deviceConfiguration as DeviceConfig = ConfigurationManager.GetSection("deviceconfigs")
For Each device As Device in deviceConfiguration.Devices
'...whatever you need to do
Next
来源：https://stackoverflow.com/questions/4080521/implementing-custom-configuration-section-handler