public static void Explicit_temporary_values_can_be_stored_in_entity_instance_2()
{
Console.WriteLine($">>>> Sample: {nameof(Explicit_temporary_values_can_be_stored_in_entity_instance_2)}");
Console.WriteLine(">>>> Shows taking generated temporary values and setting them into entity instances.");
Console.WriteLine();
Helpers.RecreateCleanDatabase();
using var context = new SomeDbContext();
#region AddBlog
var blog = new Blog();
context.Add(blog);
#endregion
#region ShowValues
Console.WriteLine($"Blog.Id value on entity instance = {blog.Id}");
Console.WriteLine($"Blog.Id value tracked by EF = {context.Entry(blog).Property(e => e.Id).CurrentValue}");
#endregion
Console.WriteLine();
#region ExplicitManipulation
var post1 = new Post();
var post2 = new Post();
var blogIdEntry = context.Entry(blog).Property(e => e.Id);
blog.Id = blogIdEntry.CurrentValue;
blogIdEntry.IsTemporary = true;
var post1IdEntry = context.Add(post1).Property(e => e.Id);
post1.Id = post1IdEntry.CurrentValue;
post1IdEntry.IsTemporary = true;
post1.BlogId = blog.Id;
var post2IdEntry = context.Add(post2).Property(e => e.Id);
post2.Id = post2IdEntry.CurrentValue;
post2IdEntry.IsTemporary = true;
post2.BlogId = blog.Id;
Console.WriteLine($"Blog has generated temporary ID = {blog.Id}");
Console.WriteLine($"Post 1 has generated temporary ID = {post1.Id} and FK to Blog = {post1.BlogId}");
Console.WriteLine($"Post 2 has generated temporary ID = {post2.Id} and FK to Blog = {post2.BlogId}");
#endregion
Console.WriteLine();
Console.WriteLine("SavingChanges...");
context.SaveChanges();
Console.WriteLine();
Console.WriteLine($"Blog has ID = {blog.Id}");
Console.WriteLine($"Post 1 has ID = {post1.Id} and FK to Blog = {post1.BlogId}");
Console.WriteLine($"Post 2 has ID = {post2.Id} and FK to Blog = {post2.BlogId}");
Console.WriteLine();
}
public async Task Counts_when_DbUpdateConcurrencyException_is_thrown(bool async)
{
TotalOptimisticConcurrencyFailures = 0;
for (var i = 1; i <= 3; i++)
{
using var context = new SomeDbContext();
var entity = new Foo();
context.Add(entity);
context.SaveChanges();
using (var innerContext = new SomeDbContext())
{
innerContext.Foos.Find(entity.Id).Token = 1;
innerContext.SaveChanges();
}
entity.Token = 2;
if (async)
{
await Assert.ThrowsAsync <DbUpdateConcurrencyException>(async() => await context.SaveChangesAsync());
}
else
{
Assert.Throws <DbUpdateConcurrencyException>(() => context.SaveChanges());
}
Assert.Equal(i, TotalOptimisticConcurrencyFailures);
}
}
public static void Handling_optional_dependents_sharing_table_with_principal_1()
{
Console.WriteLine($">>>> Sample: {nameof(Handling_optional_dependents_sharing_table_with_principal_1)}");
Console.WriteLine();
Helpers.RecreateCleanDatabase();
using (var context = new SomeDbContext())
{
var principal = new PrincipalWithOptionalDependents();
context.Add(principal);
Console.WriteLine("Saving principal with all null dependent objects:");
Console.WriteLine($" Dependent with only optional properties is {(principal.DependentWithOnlyOptionalProperties != null ? "not " : "")}null.");
Console.WriteLine($" Dependent with only required properties is {(principal.DependentWithOnlyRequiredProperties != null ? "not " : "")}null.");
Console.WriteLine($" Dependent with both optional and required properties is {(principal.DependentWithOptionalAndRequiredProperties != null ? "not " : "")}null.");
context.SaveChanges();
}
using (var context = new SomeDbContext())
{
var principal = context.PrincipalsWithOptionalDependents.Single();
Console.WriteLine("After querying back principal and dependents saved above:");
Console.WriteLine($" Dependent with only optional properties is {(principal.DependentWithOnlyOptionalProperties != null ? "not " : "")}null.");
Console.WriteLine($" Dependent with only required properties is {(principal.DependentWithOnlyRequiredProperties != null ? "not " : "")}null.");
Console.WriteLine($" Dependent with both optional and required properties is {(principal.DependentWithOptionalAndRequiredProperties != null ? "not " : "")}null.");
}
Console.WriteLine();
}
public static void Explicit_temporary_values_can_be_stored_in_entity_instance_1()
{
Console.WriteLine($">>>> Sample: {nameof(Explicit_temporary_values_can_be_stored_in_entity_instance_1)}");
Console.WriteLine(">>>> Shows using explicit temporary values with FK values to relate posts to a blog.");
Console.WriteLine();
Helpers.RecreateCleanDatabase();
using var context = new SomeDbContext();
#region MarkTemporary
var blog = new Blog {
Id = -1
};
var post1 = new Post {
Id = -1, BlogId = -1
};
var post2 = new Post {
Id = -2, BlogId = -1
};
context.Add(blog).Property(e => e.Id).IsTemporary = true;
context.Add(post1).Property(e => e.Id).IsTemporary = true;
context.Add(post2).Property(e => e.Id).IsTemporary = true;
Console.WriteLine($"Blog has explicit temporary ID = {blog.Id}");
Console.WriteLine($"Post 1 has explicit temporary ID = {post1.Id} and FK to Blog = {post1.BlogId}");
Console.WriteLine($"Post 2 has explicit temporary ID = {post2.Id} and FK to Blog = {post2.BlogId}");
#endregion
Console.WriteLine();
Console.WriteLine("SavingChanges...");
context.SaveChanges();
Console.WriteLine();
Console.WriteLine($"Blog has ID = {blog.Id}");
Console.WriteLine($"Post 1 has ID = {post1.Id} and FK to Blog = {post1.BlogId}");
Console.WriteLine($"Post 2 has ID = {post2.Id} and FK to Blog = {post2.BlogId}");
Console.WriteLine();
}
public async Task Counts_when_SaveChanges_is_called(bool async)
{
TotalSaveChanges = 0;
for (var i = 1; i <= 3; i++)
{
using var context = new SomeDbContext();
context.Add(new Foo());
_ = async ? await context.SaveChangesAsync() : context.SaveChanges();
Assert.Equal(i, TotalSaveChanges);
}
}
public static void Handling_nested_optional_dependents_sharing_table_with_principal()
{
Console.WriteLine($">>>> Sample: {nameof(Handling_nested_optional_dependents_sharing_table_with_principal)}");
Console.WriteLine();
Helpers.RecreateCleanDatabase();
using (var context = new SomeDbContext())
{
var principal = new PrincipalWithNestedOptionalDependents()
{
DependentWithOptionalNestedDependents = new()
{
Nested = new()
}
};
context.Add(principal);
Console.WriteLine("Saving principal with all non-null required dependent objects:");
Console.WriteLine($" Dependent with only optional properties is {(principal.DependentWithOptionalNestedDependents != null ? "not " : "")}null.");
Console.WriteLine($" Nested dependent with only optional properties is {(principal.DependentWithOptionalNestedDependents?.Nested != null ? "not " : "")}null.");
Console.WriteLine();
Console.WriteLine("SaveChanges will warn:");
Console.WriteLine();
context.SaveChanges();
Console.WriteLine();
}
using (var context = new SomeDbContext())
{
var principal = context.PrincipalsWithNestedOptionalDependents.Single();
Console.WriteLine("After querying back principal and dependents saved above:");
Console.WriteLine($" Dependent with only optional properties is {(principal.DependentWithOptionalNestedDependents != null ? "not " : "")}null.");
Console.WriteLine($" Nested dependent with only optional properties is {(principal.DependentWithOptionalNestedDependents?.Nested != null ? "not " : "")}null. <-- Note nested dependent is null here.");
}
Console.WriteLine();
}
