Hi. My name is Lukas Knapek, and I'm technical writer for Quest. In this video I would like to introduce you to the concept of external objects, which is a new feature in Toad Data Modeler 6.2.
External objects are basically objects that are imported into your model from any of your other models. However, as you will see, they are quite different from copies. In Toad Data Modeler, I divided my model into several smaller models to keep things neat and simple.
However, the original model had several relationships that I need to be able to express between these smaller models. For example, in my loans model I would like to keep track of book loans, which means I need the book copies entity from my books model, as well as a members entity from my members model.
So how do I do that? If I right-click the model name in Model Explorer and go to External Sources, I can see this little dialog which allows me to import nearly any object from any of my other models. So let's use this one to import the books copies entity and the members entity.
Notice how the imported entities have this little decorator inside of them. This means they are external objects and they are marked this way in model explorer as well. This is particularly useful for objects that do not have a graphic representation. Now I can proceed and add the relationships I need.
And we are done. My loans model is linked to books and members models. Another important thing about external objects is that they are not modifiable. This means you don't have to worry about external modifications. The only object you can modify is the original one.
And this brings up an interesting question. What if I do edit the original object? For example, what if I go to the original members entity and modify it by deleting attributes? Well, the great thing about external objects is that they allow us to propagate the changes made to the original object. If I go back to my loans model and right-click the Members External Entity, go to External and select Update from Source, you can see the entity has been automatically updated so it matches the original object once again.
So far these examples have been rather simple, but what about something a bit more complex? What if I want to use my authors entity in my books model? Notice that the authors entity has a little more going on. It uses a domain and it is also assigned to a user.
How do we account for that? Well, we don't actually have to. Toad Data Modeler does the work for us.
If we go back to Books Model, right-click the model name in Model Explorer, go to External Sources and mark the authors entity for import, as soon as I click the Insert button, this happens. Toad Data Modeler noticed that the entity has several dependencies and it will automatically import them as well. So when I confirm this dialog you can see that we have imported the external entity, but we have also imported an external domain and an external user.
This about covers the basics of external objects. To sum up, external objects allow you to divide your large models into smaller chunks while keeping the relationships between the parts of the model. You can propagate any changes made to the objects, and when they are imported, their dependencies are imported as well.
I hope this video helped you learn more about external objects. For more information about Toad Data Modeler, visit Quest.com/products/Toad-Data-Modeler. or visit the product community at ToadWorld.com/products/Toad-Data-Modeler. Have a nice day.