Interact with the Model API Using C#

Introduction

Once you have created basic extensions, you may want to interact with the Studio Pro model to make changes to your app. The Model API enables this functionality and is exposed via the Mendix.StudioPro.ExtensionsAPI.Model namespace.

Gaining Access to the Mendix Model SDK

To access the model, use the CurrentApp property of your extension class. All extension classes implement the Mendix.StudioPro.ExtensionsAPI.UI.UIExtensionBase base class, which provides access to CurrentApp.

The CurrentApp property exposes an implementation of IModel. This gives you access to all model elements.

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 (for example, not committed or rolled back) ITransaction for the whole app.

Transactions group changes, but do not provide a way to isolate them. Changes to a model are immediately visible to all code interacting with the model. When transaction is rolled back or is undone by a user, all included changes are reverted.

Start a Transaction

To create transaction, call IModel.StartTransaction. This method returns a transaction object that implements ITransaction.

For your changes to reflect within the model, you must first commit the transaction by calling ITransaction.Commit.

If you wish to abort or revert your changes, 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();
}

The next example below 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();
}