LightSwitch provides weakly-typed data access APIs which allow you to add general purpose code to perform common tasks. In this example, these APIs are used to implement a simple general purpose import/export. The import/export will read and write CSV files. Export will write the names of the properties as the first line of the output file. Import will read this line to get the correct column into the right property. It's designed to be called on the client from screen code. This general purpose code can be placed in its own class file in the Client/UserCode folder of your project so it can be called from any screen. In following examples, it's used on two buttons on a Customer screen, one to perform an import and one to perform an export.
The export button first gets a list of the properties to export. In this case, I'm only exporting storage properties. Storage properties are simple, scalar properties that're stored in the database. They don't include calculated or navigation properties. The call to PromptAndExportEntities() takes an enumerable list of entities to export and the list of properties to export.
More Details: Import and Export Data