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Access ConfigurationManager.AppSettings from Spring.NET xml configuration

I have a requirement that requires me to use Spring.net to get the connection string that is stored inside app.config, and then inject the resulting connection string into the object instance.

How to do this using Spring.net xml configuration?

For example, instead of my codes:

// Spring.net config: <object name="myService" type="com.acme.MyService, com.acme"> <constructor-arg type="System.String" value="myConnectionName"/> </object> // Web.config: <connectionStrings> <add name="myConnectionName" connectionString="DB_connectionstring"/> </connectionStrings> 
 // Codes: public class MyService { public MyService(string connectionName) { var connectionString = ConfigurationManager.AppSettings[connectionName]; // use connectionString to create a DB connection, etc } }

I want like this:

  // Spring.net config: <object name="myService" type="com.acme.MyService, com.acme"> <constructor-arg type="System.String" ref="retrievedConnectionString"/> </object> // How to make a call similar to "ConfigurationManager.AppSettings[connectionName]" and get the connection string from Web.config and put inside "retrievedConnectionString"? // Web.config: <connectionStrings> <add name="myConnectionName" connectionString="DB_connectionstring"/> </connectionStrings> 
 // Codes: public class MyService { public MyService(string connectionString) { // use connectionString to create a DB connection, etc } }

Is it even possible to call ConfigurationManager.AppSettings[..] from Spring.net xml config?

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2 answers

In the past, I used expression to achieve this, but through this question and answer of bbaia I found out that the best way to do this is to use a VariablePlaceholderConfigurer . When you use the VariablePlaceholderConfigurer instead of my “hack expression”, you are not attached to the appSettings / connectionStrings style configuration of your variables: you can switch to one of the VariableSources provided by spring.net or even implement your own IVariableSource .

Out of the box, spring.NET provides a VariablePlaceholderConfigurer to retrieve variables from standard .NET parameters such as AppSettings , ConnectionStrings , UserSettings and ApplicationSettings . This is partially illustrated by bbaia's answer, and you will find a complete example below.

Hacking Expressions: Calling ConfigurationManager from xml config

So, I do not advise you to use this, but this is the hack I used in the past, as applied to your configuration:

 <object object name="myService" type="com.acme.MyService, com.acme"> <constructor-arg name="Connection" expression="T(System.Configuration.ConfigurationManager).ConnectionStrings['myConnectionName']" /> </object>

You can use the same approach for ConfigurationManager.AppSettings , for example:

 <object object name="myService" type="com.acme.MyService, com.acme"> <constructor-arg name="AnotherConstructorArgument" expression="T(System.Configuration.ConfigurationManager).AppSettings['mySetting']" /> </object>

VariablePlaceholderConfigurer : .NET settings links from spring.NET xml config

You can easily configure VariablePlaceholderConfigurer to extract variables from standard .NET parameters such as AppSettings , ConnectionStrings , UserSettings and ApplicationSettings . For example, consider this xml configuration:

 <?xml version="1.0" encoding="utf-8"?> <objects xmlns="http://www.springframework.net" > <object type="Spring.Objects.Factory.Config.VariablePlaceholderConfigurer, Spring.Core"> <property name="VariableSources"> <list> <object type="Spring.Objects.Factory.Config.ConnectionStringsVariableSource, Spring.Core" /> <object type="Spring.Objects.Factory.Config.ConfigSectionVariableSource, Spring.Core"> <!-- Sections to read, sepearated by comma (leave out spaces) --> <property name="SectionNames" value="appSettings,applicationSettings/q7991262.Properties.Settings,userSettings/q7991262.Properties.Settings" /> </object> </list> </property> </object> <!-- Note that you have to append '.connectionstring' to the key! --> <object id="usingConnectionStringsVariableSource" type="q7991262.MyService, q7991262"> <property name="Connection" value="${myConnectionName.connectionString}" /> </object> <object id="configSectionVariableSource" type="q7991262.MyService, q7991262"> <property name="Connection" value="${myConnectionNameAppSettings}" /> </object> <object id="userSettingsSection" type="q7991262.MyService, q7991262"> <property name="Connection" value="${myConectionNameUserSetting}" /> </object> <object id="applicationSetting" type="q7991262.MyService, q7991262"> <property name="Connection" value="${myConectionNameApplicationSetting}" /> </object> </objects>

It reads the settings from this app.config :

 <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" > <section name="q7991262.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" /> </sectionGroup> <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" > <section name="q7991262.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" /> </sectionGroup> </configSections> <connectionStrings> <add name="myConnectionName" connectionString="From connection string section."/> </connectionStrings> <appSettings> <add key="myConnectionNameAppSettings" value="From app setting section." /> </appSettings> <userSettings> <q7991262.Properties.Settings> <setting name="myConectionNameUserSetting" serializeAs="String"> <value>My connection from user settings.</value> </setting> </q7991262.Properties.Settings> </userSettings> <applicationSettings> <q7991262.Properties.Settings> <setting name="myConectionNameApplicationSetting" serializeAs="String"> <value>My connection from application settings.</value> </setting> </q7991262.Properties.Settings> </applicationSettings> </configuration>

These configurations are taken from this working sample on github .

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Another solution is to use VariablePlaceholderConfigurer: http://www.springframework.net/doc-latest/reference/html/objects.html#objects-variablesource

The ConnectionStringsVariableSource implementation allows you to get the value from the ConnectionString section in the configuration file.

 <object type="Spring.Objects.Factory.Config.VariablePlaceholderConfigurer, Spring.Core"> <property name="VariableSources"> <list> <object type="Spring.Objects.Factory.Config.ConnectionStringsVariableSource, Spring.Core"/> </list> </property> </object> <object name="myService" type="com.acme.MyService, com.acme"> <constructor-arg type="System.String" value="${myConnectionName.connectionString}"/> </object>

Example from the Spring.NET forum: http://forum.springframework.net/showthread.php?3961

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Source: https://habr.com/ru/post/900673/

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