Interact with the Model API
Introduction
After you create some basic extensions, you want to interact with the Studio Pro model in order to make changes to your app. The Model API allows you to do just that. The model representation is exposed via the Mendix.StudioPro.ExtensionsAPI.Model namespace.
Gaining Access to the Mendix Model SDK
The easiest way to gain access to the model is by using the CurrentApp property of Extension class. All extension classes implement the Mendix.StudioPro.ExtensionsAPI.UI.UIExtensionBase base class which provides this access.
The CurrentApp property exposes an implementation of IModel. With a IModel reference you can gain access to any other model elements. However, any changes that you introduce must be contained within a model transaction.
Interacting with Model Elements
Any modification to the model must be done within a transaction; otherwise, a System.InvalidOperationException is thrown. There can be only a single active (i.e. not committed or rolled back) ITransaction for the whole app.
Transactions do not provide a way to isolate changes, but to group them. That is, any change to a model is immediately visible to all code working with the model. When transaction is rolled back programmatically or is undone by a user, all changes included in it are reverted.
To create transaction you can call IModel.StartTransaction. This method will return a transaction object which implements ITransaction.
For your changes to reflect within the model, you must first commit the transaction by calling ITransaction.Commit.
Alternatively, if you wish to abort or revert your changes, you can call ITransaction.Rollback.
Examples
The most common use case for changing an app is to change one or few properties synchronously.
In the following example, an existing folder is renamed:
using (var transaction = model.StartTransaction("rename folder"))
{
folder.Name = "New_Name";
transaction.Commit();
}
Here is another simple example. It adds an entity named testEntity and adds an attribute called testAttribute to it.
using (var transaction = model.StartTransaction("add entity"))
{
var entity = CurrentApp.Create<IEntity>();
var attr = CurrentApp.Create<IAttribute>();
entity.Name = "testEntity";
attr.Name = "testAttribute";
entity.AddAttribute(attr);
var copyEntity = CurrentApp.Copy(entity);
transaction.Commit();
}