Resource Files in ASP.NET

• To fill the property values of controls on the page.
• To update the resource values dynamically i.e. after publishing the web site, to change the Page Titles, Error Messages, and Labels Text etc.

To use resource to set control's property values, we can use

Implicit localization

• If local resource files are created in Application, then implicit localization can be used to fill the property values for the control.
• To use implicit localization, following naming convention must be used for resources in local resource file
  
  key.property
  
  Where key: Any name for the resource
  Property: Property of the control that we are localizing
  
  Ex: If we are creating resource for control label named lblErrorMsg, you need to create following key/value pairs in local resource file

  lblErrorMsg.Text  = "Error Message"
  lblErrorMsg.ForeColor= "Red"

• In aspx page, we need to use a special meta attribute in the markup for the control to specify implicit localization as-

  <asp:Label ID="lblErrorMsg" runat="server" meta:resourcekey=" lblErrorMsg" Text="Label"></asp:Label>

• No need to explicitly specify which properties are localized.
• The resourcekey value matches a key in resource file.
• At run time, ASP.NET matches resources to control properties using the resourcekey, if property value is defined in resource file, ASP.NET substitute the resource value for the property.

Explicit localization

• We use resource expression for each property of a control
• For ex: A label control that is configured to set a text and fore color property from global resource look like-

  <asp:Label ID="lblErrorMsg" runat="server" Text="<%$ Resources:ResourceFileName, lblErrorsgText %>"></asp:Label>

• The resource expression takes the following form
  
  <%$ Resources:Class, ResourceID %>
  
  Where Class: Identifies the resource file to be used
  ResourceID: Identifier of the resource to be read from resource file

Localizing Static Text

• ASP.NET Localize control is used to localize the static text on the page.
• The Localize control renders no markup, it just function to act as a place holder for static text
• At run time ASP.NET treat Localize control as a Literal control

  <asp:Localize ID="WelcomeMessage" runat="server" meta:resourcekey="literalResource" Text="WelcomeMessage" />

Retrieve Resource Values Programmatically

• Call the GetLocalResourceObject() or GetGlobalResourceObject() method to read specific resource from local or global resource file, respectively.

  string localresourcestring = string.Empty;
  string globalresourcestring = string.Empty; 
  // Get the local resource string.
  try
  {
      localresourcestring = (String)GetLocalResourceObject ("LocalResourceString1");
  }
  catch
  {
      localresourcestring = "Could not find local resource.";
  }
  // Get the global resource string.
  try
  {
      globalresourcestring = (String)GetGlobalResourceObject("MyResource", "GlobalResourceString1");
  }
  catch
  {
      globalresourcestring = "Could not find global resource.";
  }

Editing Resource Files after publishing in ASP.NET 2.0

The beauty of the resource file in ASP.NET 2.0 is modifying the resource file after the application is deployed on a server without re-compiling the entire application itself.

But the ability to do so depends on what project model we have followed for Web application in VS 2005

Project Model- Website Project Model (Default in VS2005)

• Resource file only under the App_LocalResources will get published as a raw .resx files on the server as these are not compiled. These resources files can be edited on the server as they are compiled during runtime.
• Files under the App_GlobalResources folders are compiled into individual resource specific dlls and published on the server, so we cannot edit resource under this folder

Project Model- Web Application Project(WAP)

• Files both under the App_LocalResources or App_GlobalResources folders will get published as raw .resx files which are editable.
• So with this project model, we are able to edit the resource files after publishing the web application.

Note:

• To create application with this type of model in VS 2005, you need to install"WebApplicationprojects" setup; it will install a template called"ASP.NET Web Application".
• You can download this setup from Microsoft download site.
• So whenever you create a project, template"ASP.NET Web Application" option will be available in"New Project" dialog box.
• Beauty of this template is you can add multiple projects under the solution which is not possible with VS 2005 Website.