Topic outline

• Interacting with Data in ObjectScript Using Multiple Data Models

  Interacting with Data in ObjectScript Using Multiple Data Models

  Try out the multi-model architecture of InterSystems IRIS® data platform, which lets you write code using the data models that best fit each task in your application. Multi-model access in InterSystems IRIS is possible due to an underlying data structure called globals, which allow you to interact with your data directly. These provide flexible data access while avoiding data duplication.

  Using InterSystems ObjectScript, the built-in language for developing in InterSystems IRIS, you can also interact with your data in several other ways:

  • Use industry-standard SQL to access your data, modeled as a relational table.
  • Treat the same data as objects, without the need for additional object-relational mapping software.
  • Access your data using a document data model or a system of key-value pairings.

  The same capabilities exist whether you are programming in ObjectScript or using one of the external language APIs. If you are more familiar with an external language, try this exercise in Python, Java, or .NET.

  
  

  Watch the video and try the exercise below!
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  Try It

  Try It

  In the tasks below, you will interact with a set of airport data in multiple ways. You will create the data using an object-oriented model, then retrieve that data via SQL. Finally, you will use globals to create a custom data structure to store route information.

  Click the button below to launch an InterSystems Learning Lab for use in the exercise.

  Note:

  You can follow along with these instructions on your own server instead of using the Learning Lab. To do so, first download the code sample from GitHub and compile it on your InterSystems server. You should use your own InterSystems Terminal and IDE.

  • You must be logged in to launch an InterSystems IRIS instance.

    • Log in with your existing account.
    • Don't have an InterSystems account? Create a new account.
  • Use objects to populate data

    1. Open the InterSystems Learning Lab IDE using the link in the launcher above.
    2. Using the file explorer on the left, open the file shared/quickstarts-multimodel-objectscript/Demo/Airport.cls.
       The PopulateAirports() method populates five objects and saves them to the database using an object-oriented model.
    3. Within PopulateAirports, find two functions:
       • The function used to create new Airport objects
       • The function used to save the Airport objects
    4. Right-click the folder shared/quickstarts-multimodel-objectscript/Demo/ in the explorer and click Import and Compile.
    5. Using the link in the launcher above, open the Web Terminal.
    6. Run the following ObjectScript command to populate and save five airports to the Demo.Airport database:

       do ##class(Demo.Airport).PopulateAirports()

  • Use SQL to query data

    1. Return to the Demo.Airport class file. Locate the DisplayAirports() method.
       This method runs an SQL query and returns all airports in the database. If the method is run in a terminal, it prints the data. If you inspect the code, you will see that the SQL query uses a special shorthand notation: -> This is called an implicit join, used to retrieve data from a related table.
    2. Return to the InterSystems Terminal, then run the following command:

       do ##class(Demo.Airport).DisplayAirports()

    3. Inspect the output to ensure that the airports displayed are the same as the airports created by PopulateAirports.

    It is possible to accomplish these two tasks using only objects or SQL to populate and access the data. However, using the multi-model capabilities of InterSystems IRIS, you can choose the best data model according to the task—optimizing both developer time and application performance.

  • Create a custom data structure with globals

    In your work with airport data, a new question has come up: you need to get information about routes between the airports stored in your database. Fortunately, with InterSystems IRIS you can use globals to natively store data in a custom data structure, modifying the structure to fit your specific data. This allows you to handle the route information easily, even though it was not part of the initial schema design.

    1. In the IDE, return to the Demo.Airport class and locate the StoreAirfare() method.
       This method has been created to store route information to InterSystems IRIS. Unlike PopulateAirports and DisplayAirports, the data structure used in StoreAirfare does not use the Demo.Airport data. Instead, it uses the global variable ^airport.
    2. To create the ^airport global in the current namespace, run the following command:

       do ##class(Demo.Airport).StoreAirfare()

    3. CheckAirfare method of Demo.Airport.
       This method has been created to store route information to InterSystems IRIS and print a particular route between user-supplied airports if it exists. It relies on the existence of the ^airport global.
    4. Run the methods in the InterSystems Terminal:

       do ##class(Demo.Airport).CheckAirfare("BOS", "AUS")

    5. Enter values after CheckAirfare to see if there are routes from BOS to AUS. You should find routes available.
    6. Run it again and try to find routes from BOS to LAX. This should return no available routes.

    You have now run a sample ObjectScript application with InterSystems IRIS, using three different ways to interact with the data.

• What's Next?

  What's Next?

  • Explore multiple data models with globals (exercise, 10m).
  • Learn how to build a server-side application (learning path, 2h).

  • Share Your Feedback!