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Custom section in App.Config, ConfigurationManager stops working

I have created a console app in c# that reads information from App.config. if i add things in appSettings section, i can acces them and it works, but as soon as i add some custom sections i cant read anything from it. I am using ConfigurationManager, and i have the reference for it included.
My app config looks like this:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
</startup>
<appSettings>
<add key="overwriteBackupFiles" value="False"/>
<add key="path" value="c:\temp"/>
</appSettings>
<ImageFormatsINeed>
<add key="type1" value="width=180&height=180"></add>
<add key="type2" value="width=220&height=220"></add>
<add key="type3" value="width=500&height=500"></add>
</ImageFormatsINeed>
</configuration>
and i am trying to acces those information like this:
string path = ConfigurationManager.AppSettings["path"];
var settings = ConfigurationManager.GetSection("ImageFormatsINeed");
When i didnt have the ImageFormatsINeed section i could get the path from AppSettings and it was working. But as soon as i added my ImageFormatsINeed section, everything stops working.
Now my question is how can i add custom sections in app.config that it will work, or should i just read my ImageInformation from some custom xml file or config file?

You have to use the tag <configSections> at the top in your app.config, for this case you should use the type AppSettingsSection
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="ImageFormatsINeed" type="System.Configuration.AppSettingsSection" />
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
</startup>
<appSettings>
<add key="overwriteBackupFiles" value="False"/>
<add key="path" value="c:\temp"/>
</appSettings>
<ImageFormatsINeed>
<add key="type1" value="width=180&height=180"></add>
<add key="type2" value="width=220&height=220"></add>
<add key="type3" value="width=500&height=500"></add>
</ImageFormatsINeed>
</configuration>
Then in your C# code:
NameValueCollection settings_section = ConfigurationManager.GetSection("ImageFormatsINeed") as NameValueCollection;
Console.WriteLine(settings_section["type1"]);

How to use custom configuration file or app.config in .NET application

I have MVC5 .NET 4.6.1 C# web application
I want to create a custom config file separate from web.config to store some settings my application uses.
I tried to follow this article https://support.microsoft.com/en-us/kb/815786
however the items I set in app.config:
<?xml version="1.0"?>
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.6.1" />
<httpRuntime targetFramework="4.6.1" />
</system.web>
<appSettings>
<add key="Key0" value="0" />
<add key="Key1" value="1" />
<add key="Key2" value="2" />
</appSettings>
</configuration>
are not seen in my application see , eg. they come as null:
string attr = ConfigurationManager.AppSettings["Key0"];
Why isn't it working? Am I missing something?
Alternatively I would like to create a custom config file eg. mycustom.config to define my global app settings.
EDIT
Solution I used
Follwing this post https://social.msdn.microsoft.com/Forums/vstudio/en-US/11e6d326-c32c-46b1-a9a2-1fbef96f33ee/howto-custom-configuration-files?forum=netfxbcl
In web.config:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="newAppSettings" type="System.Configuration.AppSettingsSection, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
</configSections>
<newAppSettings file="C:\mycustom.config"/>
</configuration>
Then mycustom.config
<?xml version="1.0" encoding="utf-8" ?>
<newAppSettings>
<add key="OurKey" value="OurValue"/>
</newAppSettings>
And reading the value:
System.Collections.Specialized.NameValueCollection newAppSettings = (System.Collections.Specialized.NameValueCollection)System.Configuration.ConfigurationManager.GetSection("newAppSettings");
string key = Convert.ToDateTime(newAppSettings["OurKey"]);

You can use separate config file for connection strings and app settings:
<appSettings configSource="appSettings.config" />
<connectionStrings configSource="connectionStrings.config"/>
appSettings.config file
<?xml version="1.0" encoding="utf-8" ?>
<appSettings>
<add key="Setting1" value="App setting 1" />
</appSettings>
connectionStrings.config file
<?xml version="1.0" encoding="utf-8"?>
<connectionStrings>
<add name="MyConnStr1" connectionString="My connection string" />
</connectionStrings>
Usage is same as it was before:
var setting1 = ConfigurationManager.AppSettings["Setting1"];
var connString1 = ConfigurationManager.ConnectionStrings["MyConnStr1"].ConnectionString;

//Helps to open the Root level web.config file.
Configuration webConfigApp = WebConfigurationManager.OpenWebConfiguration("~");
//Modifying the AppKey from AppValue to AppValue1
webConfigApp.AppSettings.Settings["AppKey"].Value = "AppValue1";
<appSettings>
<add key="AppKey" value="AppValue"/>
</appSettings>

App.config doesn't save some changes after app relaunch

I have a next App.config file:
<configuration>
<configSections>
<sectionGroup name="UserSettingsGroup">
<section name="dbConnectionString" type="System.Configuration.ConnectionStringsSection" />
<section name="reportsFolderSettings" type="System.Configuration.DictionarySectionHandler" />
</sectionGroup>
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0" />
</startup>
<UserSettingsGroup>
<dbConnectionString>
<add name="Host" providerName="System.Data.sqlclient" connectionString="localhost" />
<add name="Port" providerName="System.Data.sqlclient" connectionString="3050" />
........
........ etc.
</dbConnectionString>
<reportsFolderSettings>
<add key="ReportsFolder" value="C:\" />
</reportsFolderSettings>
</UserSettingsGroup>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
</startup>
<system.data>
<DbProviderFactories>
<remove invariant="FirebirdSql.Data.FirebirdClient" />
<add name="FirebirdClient Data Provider" invariant="FirebirdSql.Data.FirebirdClient" description=".NET Framework Data Provider for Firebird" type="FirebirdSql.Data.FirebirdClient.FirebirdClientFactory, FirebirdSql.Data.FirebirdClient" />
</DbProviderFactories>
</system.data>
And then I made some changes in runtime in my app's settings (I've changed the connections strings and the path for saving app's reports) and for applying them I used this code:
private void SaveSettings() {
ExeConfigurationFileMap configMap = new ExeConfigurationFileMap();
Configuration config = ConfigurationManager.OpenExeConfiguration(System.Reflection.Assembly.GetEntryAssembly().Location);
ConnectionStringsSection connectionSettings = (ConnectionStringsSection)config.SectionGroups.Get("UserSettingsGroup").Sections.Get("dbConnectionString");
connectionSettings.ConnectionStrings["Host"].ConnectionString = txtServer.Text;
connectionSettings.ConnectionStrings["Port"].ConnectionString = txtPort.Text;
connectionSettings.ConnectionStrings["DbPath"].ConnectionString = txtDBPath.Text;
connectionSettings.ConnectionStrings["User"].ConnectionString = txtUser.Text;
connectionSettings.ConnectionStrings["Password"].ConnectionString = txtPassword.Text;
connectionSettings.ConnectionStrings["Charset"].ConnectionString = cboCharset.Text;
Hashtable sectionReportsFolder = ConfigurationManager.GetSection(config.SectionGroups.Get("UserSettingsGroup").Sections.
Get("reportsFolderSettings").SectionInformation.SectionName) as Hashtable;
sectionReportsFolder.Clear();
sectionReportsFolder.Add("ReportsFolder", tbo_reportfolder.Text);
config.Save(ConfigurationSaveMode.Modified);
ConfigurationManager.RefreshSection("dbConnectionString");
ConfigurationManager.RefreshSection("reportsFolder");
}
At first glance, everything works well - I see the changes while my app is working but for some reason the app doesn't save the "reportsFolderSettings" and after relaunch I see only default value "C:\".
P.S I launch the app from .exe from "\bin\release" folder, NOT from Visual studio.

OK, I recreated Your problem and I had the same problem ; )
The problem is DictionarySectionHandler supports only reading values
This is not direct answer to Your question but it works
To work I do this:
I change type of section from:
<section name="reportsFolderSettings" type="System.Configuration.DictionarySectionHandler" />
to use the AppSettingsSection
<section name="reportsFolderSettings" type="System.Configuration.AppSettingsSection" />
Then I change:
var sectionReportsFolder = config.SectionGroups["UserSettingsGroup"].Sections["reportsFolderSettings"] as AppSettingsSection;
sectionReportsFolder.Settings.Clear();
sectionReportsFolder.Settings.Add("ReportsFolder", tbo_reportfolder.Text);
And then everything is work good. I tested this.

Window service generates exception while reading 'ConfigurationManager.AppSettings["FilePath"].ToString()'

I am making a windows service.
It contain one App.config file as below:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="SQLConnectionStr" value="Data Source=192.168.1.116;Initial Catalog=Conezone;User Id=sa;Password=saadmin#123;"/>
<add key="FilePath" value="D:\Autoparts Guru\LINES2\"/>
</appSettings>
</configuration>
To get FilePath value in service code, I am writing
ConfigurationManager.AppSettings["FilePath"].ToString()
But it generates NullReferenceException.
Hope i get the answer quickly.

This code may help you:
App.config:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
<appSettings>
<add key="SQLConnectionStr" value="Data Source=000.000.000.000;Initial Catalog=mydb;User Id=sa;Password=sa;"/>
<add key="FilePath" value="myfilepath"/>
</appSettings>
</configuration>
Namespace
using System.Configuration;
Code:
string filepath = string.Empty;
filepath = ConfigurationManager.AppSettings["FilePath"];

Mindscape.LightSpeed Database connectivity problem

I'm using Mindspace.Lightspeed in my C# desktop application for the first time but I'm getting errors and unable to connect to database.
My App.config contains the following code:
<?xml version="1.0" encoding="utf-8" ?><configuration>
<configSections>
<section name="lightSpeedContext" type="Mindscape.LightSpeed.Configuration.LightSpeedConfigurationSection,Mindscape.LightSpeed" /></configSections><connectionStrings>
<add name="DefectsConStr" connectionString="Data Source=.\sqlexpress2k5;Initial Catalog=Defects;Persist Security Info=True;User ID=sa;Password=123"
providerName="System.Data.SqlClient" /></connectionStrings> <lightSpeedContext>
<add name="Development" connectionStringName="DefectsConStr" dataProvider="SqlServer2005"/> </lightSpeedContext> </configuration>

I have managed to reproduce your problem, you need to change your configuration file so that the section name is
lightSpeedContexts and not lightSpeedContext
see my configuration file
<?xml version="1.0"?>
<configuration>
<configSections>
<section name="lightSpeedContexts" type="Mindscape.LightSpeed.Configuration.LightSpeedConfigurationSection,Mindscape.LightSpeed"/>
</configSections>
<connectionStrings>
<add name="Blog" connectionString="Data Source=Blog.dat"/>
</connectionStrings>
<lightSpeedContexts>
<add name="Blog" connectionStringName="Blog" dataProvider="SQLite3" identityMethod="KeyTable" pluralizeTableNames="false"/>
</lightSpeedContexts>
</configuration>