04 integrate entityframework
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This document discusses integrating AngularJS, ASP.NET Web API, SignalR, and Entity Framework. It begins with an overview of object-relational mapping and Entity Framework. It then demonstrates how to develop an ASP.NET Web API with Entity Framework using Code First migrations to initialize and seed a database. Different data loading strategies like eager, lazy, and explicit loading are explained. Issues with navigation properties and circular references are addressed. The document also covers creating DTOs, mapping entities to DTOs with LINQ and AutoMapper, and integrating everything into a real-time dashboard using SignalR with Entity Framework backend.
![Use Fiddler2 to Get request
/api/books (Lazy Load)
• When lazy loading is enabled, accessing the Author property on books[0] causes EF to
query the database for the author
• Lazy loading requires multiple database trips, because EF sends a query each time it
retrieves a related entity](https://image.slidesharecdn.com/04integrateentityframework-141218002447-conversion-gate01/85/04-integrate-entityframework-35-320.jpg)
04 integrate entityframework
- 1. AngularJS + Asp.Net Web Api + Signalr + EF6：前後端整合篇 開發技巧實戰系列(4/6) - Web 前後端整合 講師: 郭二文 (erhwenkuo@gmail.com)
- 2. Document, Source code & Training Video (4/6) • https://github.com/erhwenkuo/PracticalCoding
- 3. Previous Training Session Document, Source code & Training Video (3/6) • https://www.youtube.com/watch?v=z UXYuCicBDc&feature=youtu.be • http://www.slideshare.net/erhwenku o/03-integrate-webapisignalr
- 4. Agenda • ORM Technologies – Basic Concepts • Entity Framework - Overview • Developing & Testing of ASP.Net EF6 • Highchart , AngularJS ,Web API2 , SignalR2 + EF6 Integration
- 5. ORM Technologies – Basic Concepts
- 6. Introduction to Object-Relational Mapping (ORM) • Object-Relational Mapping (ORM) is a programming technique for automatic mapping and converting data • Between relational database tables and object-oriented classes and objects • ORM creates a "virtual object database“ • Which can be used from within the programming language, e.g. C# or Java • ORM frameworks automate the ORM process • A.k.a. object-relational persistence frameworks
- 7. Functionality of ORM • ORM frameworks typically provide the following functionality: • Creating object model by database schema • Creating database schema by object model • Querying data by object-oriented API • Data manipulation operations • CRUD – create, retrieve, update, delete • ORM frameworks automatically generate SQL to perform the requested data operations
- 8. ORM Mapping - Example Relational database schema ORM Entities (C# Classes) ORM Framework
- 9. ORM Advantages • Developer productivity • Writing less code • Abstract from differences between object and relational world • Complexity hidden within ORM • Manageability of the CRUD operations for complex relationships • Easier maintainability
- 11. Overview of EF • Entity Framework (EF) is a standard ORM framework, part of .NET • Provides a run-time infrastructure for managing SQL-based database data as .NET objects • The relational database schema is mapped to an object model (classes and associations) • Visual Studio has built-in tools for generating Entity Framework SQL data mappings • Data mappings consist of C# classes and XML • A standard data manipulation API is provided
- 12. Different Ways EF Access Database
- 13. Developing & Testing of ASP.Net Entity Framework6
- 14. Develop WEP API with Entity Framework 6 • This tutorial uses ASP.NET Web API 2 with Entity Framework 6 to create a web application that manipulates a back-end database. • “Code First” approach will be demonstrated
- 15. Environment Setup 1. Use NuGet to search “EntityFramework” 2. Click “Install”
- 16. Environment Setup 1. Add a SQL Server Database “PracticalCoding.mdf” under “App_Data” folder
- 17. Add Models
- 18. Add Entity Framework DbContext Identify which connection setting will be used Create “DbSet” for “Authors” & “Books” Inheritance “DbContext”
- 19. Add “ConnectionStrings” Setting 1. Add “connectionStrings” in “Web.config” to link “PracticalCoding.mdf” to “EF6DbContext”
- 22. Code First - Migrations Features 1. “Tools” “Library Package Manager””Package Manager Console” 2. Key in “Enable-Migrations” in “Package Manager Console” 1 2 3
- 23. Code First – Seeding Database 1. Modify “Configuration.cs” 2. Add below code to initialize (seeding) Database
- 24. Code First - Migrations Features: Add-Migration & Update-Database 1. Key in “Add-Migration Initial” in “Package Manager Console” and Hit “Enter” 1 2 3 3
- 25. Code First - Migrations Features: Add-Migration & Update-Database 1. Key in “Update-Database” in “Package Manager Console” 1 2 3 4 4 4
- 26. Explore & Test the Web API 1. Hit “F5” to run “PracticalCoding.Web” 2. Use “Fiddler2” to test below Web APIs Demo Page
- 27. Code First – Migration Commands • Commands Reference: • http://coding.abel.nu/2012/03/ef-migrations-command-reference/#Update- Database • Most Frequent Used: • Enable-Migrations: Enables Code First Migrations in a project. • Add-Migration: Scaffolds a migration script for any pending model changes. • Update-Database: Applies any pending migrations to the database. • Get-Migrations: Displays the migrations that have been applied to the target database.
- 28. Handling Entity Relations • Eager Loading versus Lazy Loading • When using EF with a relational database, it's important to understand how EF loads related data • Enable SQL queries that EF generates & output to Debug Trace Console
- 29. Use Fiddler2 to Get request /api/books • You can see that the Author property is null, even though the book contains a valid AuthorId • The “SELECT” statement takes from the Books tables, and does not reference Author table
- 30. Entity Framework Data Loading Strategy • Very important to know how Entity Framework loading related data • Eager Loading • Lazy Loading • Explicit Loading
- 31. Entity Framework Data Loading Strategy (Eager Loading) • With eager loading, EF loads related entities as part of the initial database query • Copy “BooksController.cs” to “BooksEagerLoadController.cs” • To perform eager loading, use the System.Data.Entity.Include extension method as show below: This tells EF to include the Author data in the query
- 32. Use Fiddler2 to Get request /api/books (Eager Load) • The trace log shows that EF performed a join on the Book and Author tables.
- 33. Entity Framework Data Loading Strategy (Lazy Loading) • With lazy loading, EF automatically loads a related entity when the navigation property for that entity is dereferenced. • To enable lazy loading, make the navigation property virtual. For example, in the Book class: “virtual” tells EF to lazy load the Author property
- 34. Entity Framework Data Loading Strategy (Lazy Loading) • Key in “Add-Migration AddLazyAuthorBook” in “Package Manager Console” • Key in “Update-Datebase” in “Package Manager Console” 1 2 3
- 35. Use Fiddler2 to Get request /api/books (Lazy Load) • When lazy loading is enabled, accessing the Author property on books[0] causes EF to query the database for the author • Lazy loading requires multiple database trips, because EF sends a query each time it retrieves a related entity
- 36. Use Fiddler2 to Get request /api/books (Lazy Load) • The trace log shows that EF performed a join on the Book and Author tables. 1 2 3 4 5 6
- 37. Navigation Properties and Circular References • If there is “Circular References”, System will encounter problem while serialize the model
- 38. Navigation Properties and Circular References • Modify “EF6DBContext” to add DbSets for CirRefBook & CirRefAuthor • Key in “Add-Migration AddCirRefAuthorBook” in “Package Manager Console” • Key in “Update-Datebase” in “Package Manager Console” • Add New WebApi Controller “CirRefBooksNGController”
- 39. Navigation Properties and Circular References Unit Test with Fiddler2 Demo
- 40. Create Data Transfer Objects (DTOs) • Remove circular references • Hide particular properties that clients are not supposed to view. • Omit some properties in order to reduce payload size. • Flatten object graphs that contain nested objects, to make them more convenient for clients. • Avoid “over-posting” vulnerabilities. • Decouple service layer from database/data storage layer.
- 41. Create Data Transfer Objects (DTOs)
- 42. Domain Entity mapping to DTO (LINQ) – CirRefBooksLINQController.cs POST the data via remote WebApi using angular $http service object Use LINQ to map from Entity to DTO Object. It works, but … just tedious!!
- 43. Navigation Properties and Circular References Unit Test with Fiddler2 Demo
- 44. Install “AutoMapper” 3rd Library 1. Use NuGet to search “AutoMapper” 2. Click “Install”
- 45. Domain Entity mapping to DTO (AutoMapper) – CirRefBooksController.cs The code is much clean and programmer is happy!! The code is much clean and easy. The programmer is happy again!!
- 46. Navigation Properties and Circular References Unit Test with Fiddler2 Demo
- 47. Highchart , AngularJS ,Web API2 , SignalR2 + Entity Framework 6 Integration
- 48. Integration with Entity Framework • Copy “08_AngularWithSignalR” to “09_IntegrationWithEF6 ”
- 49. Modify EF Context for Dashboard • Modify “EF6DbContext.cs” to add DbSet for “Chartdata” object Create “DbSet” for “Chartdata”
- 50. Add Entity Framework Annotation • Modify “Models/Dashboard/Chartdata.cs” to add some EF annotation It tell Database to automatically generate an Unique ID
- 51. Migration & Update Database • Key in “Add-Migration AddChartdata” in “Package Manager Console” • Key in “Update-Datebase” in “Package Manager Console” 1 2 3
- 54. Switch “MemDashboardRepo” to “EF6DashboardRepo” • Copy “SignalRDashboardController.cs” to “EF6DashboardController.cs” Switch our Repository from “Memory” to “Entity Framework” Dispose “Entity Framework” context object to release database connection
- 55. Modify Our Angular “ChartDataFactory” • Switch angular $http communication end point to our new WebAPI url Before After
- 56. Integration with Entity Framework6 1. Select “09_Integration/index.html” and Hit “F5” to run 2. Open Multi-Browers to see charts reflect changes whenever C/U/D operations occurred Demo
- 57. Next Session: AngularJS + Highchart + Asp.Net WebApi2 + SignalR2 + Entity Framework6 + Redis
Editor's Notes
- #2: 開發技巧實戰 1. AngularJS入門篇 2. AngularJS + HighChart：完美網頁圖表整合篇 3. AngularJS + Asp.Net WebApi 2 +SignalR：前後端整合篇 4. AngularJS + Asp.Net WebApi 2+ SignalR + Entity Framework 6 (ORM)：前後端整合篇 5. AngularJS + Asp.Net WebApi 2+ SignalR +Entity Framework 6 (ORM) + Redis (Nosql)：前後端整合篇 6. AngularJS + Asp.Net WebApi 2+ SignalR +Entity Framework 6 (ORM) + Redis (Nosql) + Elasticsearch (全文檢索)：前後端整合篇
- #4: 本章節的內容會延續前一個Session的知識與內容, 如果對前一章節不熟悉的話, 可以在Yoube或Slideshare找到文件與教學錄影