9. XAML & WPF - WPF and Databases

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WPF and Databases Telerik Software Academy: http://academy.telerik.com/school-academy/meetings/details/2012/02/02/desktop-applications-csharp-wpf The website and all video materials are in Bulgarian. Data Access Layer Linq-to-Entities Linq-to-XML Accessing the Data Layer DataContext Master Detail Data Persister Paging WPF and Databases

Text of 9. XAML & WPF - WPF and Databases

  • 1. WPF and Databases LINQ-to-Entities, Data Persisters, Master DatailDoncho MinkovTechnical Trainerhttp://www.minkov.itTelerik Software Academyacademy.telerik.com

2. Table of Contents Data Access Layer Linq-to-Entities Linq-to-XML Accessing the Data Layer DataContext Master Detail Data Persister Paging WPF and Databases 3. Data Access Layer 4. Data Access Layer The Data Access Layer is a essential Used for access to the database Class Library with single EntityModel class This way we can use the same DAL with many applications 5. Data Access Layer Live Demo 6. Accessing the Data Layer 7. The DataContext When adding a reference to the DAL project We can instantiate an entity model in the XAML And set it for DataContext 8. Accessing DAL After instantiating the EntityModel we can simplybind some of the entities to a ItemCollection ListBox, ListView, TreeView, etc. In MVVM it is not possible to access the DALdirectly Done through the ViewModel In MVVM we need a DataPersister object 9. Accessing the Data Layer Live Demo 10. Master Detail 11. Master Detail What is Master Detail? When selecting a Category Show category info Show products in this category 12. Master Datail in MVVM Consider we have the property Categories in the ViewModel Somehow it gets data from the Model Since Categories is a IEnumerable we can get its ICollectionView Now we got the CurrentItem Can make property Products that returns the products of the CurrentItem 13. Master Detail Live Demo 14. Data PersisterThe way to collect information 15. What is a Data Persister? The Data Persister is the object that gives data to the Model Sometimes it is merged with the Model It could be an EntityDataModel It could be a Linq-to-XML object It could just an object we created How the Data Persister helps? Easier for mocking (unit testing) Better reusability 16. The DataPersister The DataPersisteris the class that makes the connection with the Data (RDB, XML or object) Responsible for the CRUD May have validation With this object the Model is pretty clean Almost no programming logic Loose coupling 17. Data PersisterLive Demo 18. PagingWhat is paging and why we need it? 19. What is Paging? A memory-management scheme A computer can store and retrieve data fromsecondary storage for use in main memory With paging the applicationretrieves data from secondary storage in same-size blocks called pages Why use paging? Imagine a Database with over a million records Store them in the dynamic memory at once? Or take them by pieces with 100 records? 20. Paging TODO 21. PagingLive Demo 22. WPF and Databases With MVVM 23. WPF and Databases Consider the usual case You have categories with products in aDatabase CRUD operations should be implemented You have the following: When selecting the DataContext of the Grid You get a Person object 24. Categories Editor Live Demo 25. WPF and Databases , BG Coder - - online judge , ASP.NET - , , C#, .NET, ASP.NET http://academy.telerik.com ASP.NET MVC HTML, SQL, C#, .NET, ASP.NET MVC SEO - , , iPhone, Android, WP7, PhoneGap , HTML, CSS, JavaScript, Photoshop - free C# book, C#, Java, C# - " " " cloud " C# , , 26. Exercises1. Create a database holding continents, countries and town. Countries have name, language, population and continent. Towns have name, population and country. Implement a WPF application that shows the continents in a ComboBox, countries in a ListView and the towns in a ListView and allows master-detail navigation. Use Entity Framework. Use paging and sorting for the long lists.2. Implement add / edit / delete for the continents, countries, towns and languages. Handle the possible errors accordingly. Implement validation logic. 26 27. Exercises (2)3. Add a flag for each country which should be a PNG image, stored in the database, displayed along with the country data. Implement "change flag" functionality by uploading a PNG image. 27 28. Free Trainings @ Telerik Academy Desktop Applications with C# and WPF academy.telerik.com/ Telerik Software Academy academy.telerik.com Telerik Academy @ Facebook facebook.com/TelerikAcademy Telerik Software Academy Forums forums.academy.telerik.com