Entity Framework & LINQ (Language Integrated Query) MIS 324 -- Professor Sandvig 7/26/2019 Entity Framework & LINQ (Language Integrated Query) MIS 324 Professor Sandvig

MIS 324 -- Professor Sandvig 7/26/2019 Outline Entity Framework Model generation Scaffolding Controllers & views LINQ Language integrated query

What is Entity Framework MIS 324 -- Professor Sandvig 7/26/2019 What is Entity Framework Short version: Code-less CRUD web interface Microsoft’s ORM (object relation mapper) Wizards create model, controller, views from database

What is Entity Framework Dapper lightweight ORM Fast Uses standard SQL queries EF is ORM + code writing wizards

EF Model Examines database Example: Generates model of database tables Database with three tables VS: Add  New Item  ADO.NET Entity Data Model

EF Controller & Views VS: Add > New Scaffolded Item Generates: Controller with CRUD methods Views for CRUD

EF Controller & Views Run Scaffolding wizard for each table CRUD Interface

Entity Framework VS wizards: Create models from database Create database from model Create model and database from db.model Create MVC controller and views from models

Entity Framework Very convenient Scaffolding wizard generates: Controller Views Time: minutes instead of hours Can add validation, customize view, etc.

LINQ Language Integrated Query Used by Entity Framework Alternative to SQL Select, sort, filter, etc. Used by Entity Framework Eliminates disconnect between database & code

MIS 324 -- Professor Sandvig 7/26/2019 LINQ - Intellisense We have data models Same as database LINQ examines models Provides Intellisense for writing queries

LINQ SQL Comparison Example: Sql: LINQ string sql = "select Id, Fname, Lname, street, city, state from students where id = @Id"; Execute query and map query results to model LINQ Student student = db.Students.Find(id);

LINQ - Intellisense See Student LINQ Controller handout

LINQ LINQ can query many collection types:

MIS 324 -- Professor Sandvig 7/26/2019 Drawbacks Microsoft propriety technology Not useful outside MS universe LINQ query syntax different than SQL Better in some ways Synchronization between database and entity objects Change database Rebuild entity objects

HW 1 Tutorial HW 1: Getting Started with Entity Framework 6 Database First using MVC 5 Steps: Create database with three tables: Students, courses, enrollments Create EF model with wizard Create controllers and view with wizard

Summary Entity Framework Very handy for CRUD operations VS wizards create: Models Controllers Views