It is easy to add a single file upload button in the MDriven Designer, but to handle multiple files you'll have to create a component.

Model for this example

The model for the example is a project with some documents. Each document holds the file (a blob) and a filename (a string). The goal is to make it possible to choose several documents in the file browser and upload all of them.

Setting up the ViewModel

• Create a view model. It should have a root, which in this case should be a project. The project holds the list / container of documents. We will need the ID of the view model class.
• Create a variable (here named vUploadFileTarget). It should be of a type that could store a file (blob). In this example we choose the Document type. This variable will be used to temporary store each file since we are limited to one single upload at a time.