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Re-write cascade delete documentation
Fixes #2906 Fixes #828 Fixes #473
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9 files changed

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-209
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9 files changed

+1475
-209
lines changed

‎entity-framework/core/saving/cascade-delete.md

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‎samples/core/CascadeDeletes/CascadeDeletes.csproj

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>netcoreapp3.1</TargetFramework>
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<RootNamespace />
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</PropertyGroup>
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<ItemGroup>
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<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="5.0.1" />
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<PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="5.0.1" />
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<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="5.0.1" />
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</ItemGroup>
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</Project>

‎samples/core/CascadeDeletes/IntroOptionalSamples.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using Microsoft.EntityFrameworkCore;
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using Microsoft.EntityFrameworkCore.Diagnostics;
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namespace IntroOptional
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{
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public static class IntroOptionalSamples
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{
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public static void Deleting_principal_parent_1b()
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{
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Console.WriteLine($">>>> Sample: {nameof(Deleting_principal_parent_1b)}");
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Console.WriteLine();
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Helpers.RecreateCleanDatabase();
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Helpers.PopulateDatabase();
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#region Deleting_principal_parent_1b()
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using var context = new BlogsContext();
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var blog = context.Blogs.OrderBy(e => e.Name).Include(e => e.Posts).First();
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context.Remove(blog);
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context.SaveChanges();
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#endregion
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Console.WriteLine();
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}
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public static void Severing_a_relationship_1b()
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{
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Console.WriteLine($">>>> Sample: {nameof(Severing_a_relationship_1b)}");
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Console.WriteLine();
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Helpers.RecreateCleanDatabase();
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Helpers.PopulateDatabase();
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#region Severing_a_relationship_1b()
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using var context = new BlogsContext();
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var blog = context.Blogs.OrderBy(e => e.Name).Include(e => e.Posts).First();
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foreach (var post in blog.Posts)
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{
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post.Blog = null;
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}
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context.SaveChanges();
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#endregion
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Console.WriteLine();
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}
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public static void Severing_a_relationship_2b()
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{
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Console.WriteLine($">>>> Sample: {nameof(Severing_a_relationship_2b)}");
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Console.WriteLine();
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Helpers.RecreateCleanDatabase();
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Helpers.PopulateDatabase();
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#region Severing_a_relationship_1b()
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using var context = new BlogsContext();
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var blog = context.Blogs.OrderBy(e => e.Name).Include(e => e.Posts).First();
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blog.Posts.Clear();
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context.SaveChanges();
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#endregion
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Console.WriteLine();
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}
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}
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public static class Helpers
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{
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public static void RecreateCleanDatabase()
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{
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using var context = new BlogsContext(quiet: true);
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context.Database.EnsureDeleted();
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context.Database.EnsureCreated();
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}
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public static void PopulateDatabase()
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{
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using var context = new BlogsContext(quiet: true);
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context.Add(
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new Blog
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{
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Name = ".NET Blog",
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Posts =
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{
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new Post
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{
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Title = "Announcing the Release of EF Core 5.0",
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Content = "Announcing the release of EF Core 5.0, a full featured cross-platform..."
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},
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new Post
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{
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Title = "Announcing F# 5",
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Content = "F# 5 is the latest version of F#, the functional programming language..."
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},
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}
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});
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context.SaveChanges();
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}
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}
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#region Model
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public class Blog
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{
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public int Id { get; set; }
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public string Name { get; set; }
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public IList<Post> Posts { get; } = new List<Post>();
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}
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public class Post
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{
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public int Id { get; set; }
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public string Title { get; set; }
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public string Content { get; set; }
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public int? BlogId { get; set; }
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public Blog Blog { get; set; }
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}
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#endregion
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public class BlogsContext : DbContext
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{
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private readonly bool _quiet;
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public BlogsContext(bool quiet = false)
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{
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_quiet = quiet;
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}
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public DbSet<Blog> Blogs { get; set; }
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public DbSet<Post> Posts { get; set; }
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protected override void OnModelCreating(ModelBuilder modelBuilder)
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{
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modelBuilder
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.Entity<Blog>()
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.HasMany(e => e.Posts)
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.WithOne(e => e.Blog)
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.OnDelete(DeleteBehavior.ClientSetNull);
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}
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protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
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{
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optionsBuilder
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.EnableSensitiveDataLogging()
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.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Scratch;ConnectRetryCount=0");
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//.UseSqlite("DataSource=test.db");
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if (!_quiet)
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{
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optionsBuilder.LogTo(Console.WriteLine, new[] { RelationalEventId.CommandExecuted });
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}
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}
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}
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}

‎samples/core/CascadeDeletes/IntroRequiredSamples.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using Microsoft.EntityFrameworkCore;
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using Microsoft.EntityFrameworkCore.Diagnostics;
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namespace IntroRequired
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{
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public static class IntroRequiredSamples
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{
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public static void Deleting_principal_parent_1()
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{
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Console.WriteLine($">>>> Sample: {nameof(Deleting_principal_parent_1)}");
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Console.WriteLine();
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Helpers.RecreateCleanDatabase();
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Helpers.PopulateDatabase();
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#region Deleting_principal_parent_1
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using var context = new BlogsContext();
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var blog = context.Blogs.OrderBy(e => e.Name).Include(e => e.Posts).First();
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context.Remove(blog);
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context.SaveChanges();
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#endregion
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Console.WriteLine();
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}
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public static void Severing_a_relationship_1()
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{
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Console.WriteLine($">>>> Sample: {nameof(Severing_a_relationship_1)}");
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Console.WriteLine();
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Helpers.RecreateCleanDatabase();
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Helpers.PopulateDatabase();
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#region Severing_a_relationship_1
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using var context = new BlogsContext();
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var blog = context.Blogs.OrderBy(e => e.Name).Include(e => e.Posts).First();
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foreach (var post in blog.Posts)
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{
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post.Blog = null;
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}
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context.SaveChanges();
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#endregion
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Console.WriteLine();
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}
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public static void Severing_a_relationship_2()
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{
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Console.WriteLine($">>>> Sample: {nameof(Severing_a_relationship_2)}");
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Console.WriteLine();
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Helpers.RecreateCleanDatabase();
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Helpers.PopulateDatabase();
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#region Severing_a_relationship_2
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using var context = new BlogsContext();
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var blog = context.Blogs.OrderBy(e => e.Name).Include(e => e.Posts).First();
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blog.Posts.Clear();
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context.SaveChanges();
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#endregion
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Console.WriteLine();
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}
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public static void Where_cascading_behaviors_happen_1()
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{
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Console.WriteLine($">>>> Sample: {nameof(Where_cascading_behaviors_happen_1)}");
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Console.WriteLine();
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Helpers.RecreateCleanDatabase();
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Helpers.PopulateDatabase();
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#region Where_cascading_behaviors_happen_1
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using var context = new BlogsContext();
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var blog = context.Blogs.OrderBy(e => e.Name).First();
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context.Remove(blog);
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context.SaveChanges();
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#endregion
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Console.WriteLine();
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}
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}
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public static class Helpers
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{
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public static void RecreateCleanDatabase()
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{
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using var context = new BlogsContext(quiet: true);
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context.Database.EnsureDeleted();
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context.Database.EnsureCreated();
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}
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public static void PopulateDatabase()
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{
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using var context = new BlogsContext(quiet: true);
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context.Add(
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new Blog
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{
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Name = ".NET Blog",
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Posts =
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{
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new Post
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{
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Title = "Announcing the Release of EF Core 5.0",
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Content = "Announcing the release of EF Core 5.0, a full featured cross-platform..."
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},
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new Post
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{
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Title = "Announcing F# 5",
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Content = "F# 5 is the latest version of F#, the functional programming language..."
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},
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}
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});
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context.SaveChanges();
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}
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}
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#region Model
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public class Blog
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{
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public int Id { get; set; }
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public string Name { get; set; }
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public IList<Post> Posts { get; } = new List<Post>();
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}
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public class Post
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{
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public int Id { get; set; }
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public string Title { get; set; }
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public string Content { get; set; }
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public int BlogId { get; set; }
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public Blog Blog { get; set; }
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}
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#endregion
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public class BlogsContext : DbContext
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{
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private readonly bool _quiet;
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public BlogsContext(bool quiet = false)
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{
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_quiet = quiet;
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}
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public DbSet<Blog> Blogs { get; set; }
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public DbSet<Post> Posts { get; set; }
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protected override void OnModelCreating(ModelBuilder modelBuilder)
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{
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modelBuilder.Entity<Blog>().HasMany(e => e.Posts).WithOne(e => e.Blog); //.OnDelete(DeleteBehavior.ClientSetNull);
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}
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protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
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{
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optionsBuilder
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.EnableSensitiveDataLogging()
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.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Scratch;ConnectRetryCount=0");
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//.UseSqlite("DataSource=test.db");
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if (!_quiet)
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{
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optionsBuilder.LogTo(Console.WriteLine, new[] { RelationalEventId.CommandExecuted });
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}
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}
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}
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}

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