✨ 69 hierarchy ids (#77)

* Implemented hierarchy IDs

* Added readme

EfCoreSamples.sln

@@ -64,6 +64,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EnhancedJsonColumns", "Enha
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EnhancedBulkUpdateAndDelete", "EnhancedBulkUpdateAndDelete\EnhancedBulkUpdateAndDelete.csproj", "{89031EE1-2782-404B-B06E-FCFEE98BAC1F}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HierarchyIds", "HierarchyIds\HierarchyIds.csproj", "{B18EB327-BF8D-4D61-B9F1-8392A9678F55}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -182,6 +184,10 @@ Global
 		{89031EE1-2782-404B-B06E-FCFEE98BAC1F}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{89031EE1-2782-404B-B06E-FCFEE98BAC1F}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{89031EE1-2782-404B-B06E-FCFEE98BAC1F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B18EB327-BF8D-4D61-B9F1-8392A9678F55}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B18EB327-BF8D-4D61-B9F1-8392A9678F55}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B18EB327-BF8D-4D61-B9F1-8392A9678F55}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B18EB327-BF8D-4D61-B9F1-8392A9678F55}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

HierarchyIds/ApplicationDbContext.cs

@@ -0,0 +1,19 @@
+using Common;
+using Microsoft.EntityFrameworkCore;
+
+namespace HierarchyIds;
+
+public class ApplicationDbContext : DbContext
+{
+    public DbSet<Employee> Employees => Set<Employee>();
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+        optionsBuilder
+            .UseSqlServer(DbConnectionFactory.Create("HierarchyIds"), builder => builder.UseHierarchyId());
+    }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+    }
+}

HierarchyIds/Employee.cs

@@ -0,0 +1,15 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace HierarchyIds;
+
+public class Employee
+{
+    public int Id { get; private set; }
+    public required HierarchyId Path { get; init; }
+    public required string Name { get; init; }
+
+    public override string ToString()
+    {
+        return $"Id: {Id}, Name: {Name}, Path: {Path}";
+    }
+}

HierarchyIds/HierarchyIds.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer.HierarchyId" Version="8.0.0" />
+    </ItemGroup>
+
+</Project>

HierarchyIds/Program.cs

@@ -0,0 +1,54 @@
+using HierarchyIds;
+using Microsoft.EntityFrameworkCore;
+
+Console.WriteLine("Hierarchy IDs Sample");
+
+using var db = new ApplicationDbContext();
+db.Database.EnsureDeleted();
+db.Database.EnsureCreated();
+
+var employees = new List<Employee>
+{
+    new() { Name = "CEO", Path = HierarchyId.Parse("/")},
+    new() { Name = "Product Manager", Path = HierarchyId.Parse("/1/")},
+    new() { Name = "Tech Lead", Path = HierarchyId.Parse("/1/1/")},
+    new() { Name = "Senior Dev", Path = HierarchyId.Parse("/1/1/1/")},
+    new() { Name = "Junior Dev", Path = HierarchyId.Parse("/1/1/2/")},
+    new() { Name = "Intern", Path = HierarchyId.Parse("/1/1/3/")},
+};
+
+db.Employees.AddRange(employees);
+db.SaveChanges();
+
+var techLead = db.Employees.First(e => e.Path == HierarchyId.Parse("/1/1/"));
+
+// Get tech lead subordinates
+var techLeadSubordinates = db.Employees
+    .AsNoTracking()
+    .Where(e => e.Path.IsDescendantOf(techLead.Path))
+    .ToList();
+
+Console.WriteLine("Tech Lead Team");
+techLeadSubordinates.ForEach(Console.WriteLine);
+
+// Get tech lead parents
+var techLeadManagers = FindAllAncestors("Tech Lead").ToList();
+Console.WriteLine("Tech Lead Managers");
+techLeadManagers.ForEach(Console.WriteLine);
+
+var ceo = db.Employees.First(e => e.Path == HierarchyId.Parse("/"));
+
+Console.WriteLine($"Is Tech Lead a descendant of CEO? {techLead.Path.IsDescendantOf(ceo.Path)}");
+Console.WriteLine($"Is CEO a descendant of Tech Lead? {ceo.Path.IsDescendantOf(techLead.Path)}");
+
+Console.ReadLine();
+
+IQueryable<Employee> FindAllAncestors(string name)
+    => db.Employees.Where(
+            ancestor => db.Employees
+                .Single(
+                    descendent =>
+                        descendent.Name == name
+                        && ancestor.Id != descendent.Id)
+                .Path.IsDescendantOf(ancestor.Path))
+        .OrderByDescending(ancestor => ancestor.Path.GetLevel());

HierarchyIds/readme.md

@@ -0,0 +1,16 @@
+# Hierarchy IDs
+
+Hierarchy IDs are a special data type in SQL Server that allow you to store and query hierarchical data.  This is a great way to store data that has a parent-child relationship, such as a file system, organizational chart, or product categories.
+
+The DB is then able to run queries such as finding all descendants of a node, or finding the common ancestor of two nodes.
+
+NOTE: You will need the CLR enabled on your SQL Server instance for this to work.  The Azure SQL Edge Docker image does not support this.
+
+
+## Use Cases
+
+- Store and query hierarchical (i.e. tree-like) data
+
+## Resources
+
+- [EF Core Docs | Hierarchy IDs](https://learn.microsoft.com/en-us/ef/core/what-is-new/ef-core-8.0/whatsnew#hierarchyid-in-net-and-ef-core)

docker-compose.yml

@@ -5,11 +5,9 @@ services:
     environment:
       ACCEPT_EULA: "Y"
       SA_PASSWORD: "yourStrong(!)Password"
-    # mssql server image isn't available for arm64 architecture, so we use azure-sql instead
-    image: mcr.microsoft.com/azure-sql-edge:latest
     #container_name: "ef-core-samples"
-    # If you really want to use MS SQL Server, uncomment the following line
-    #image: mcr.microsoft.com/mssql/server
+    # NOTE: can't use azure-sql-edge as it doesn't support .NET CLR.
+    image: mcr.microsoft.com/mssql/server
     ports:
       # {{exposed}}:{{internal}} - you'll need to contain the exposed ports if you have more than one DB server running at a time
       - 1433:1433