Added example that uses a different database per tenant

JsonApiDotNetCore.sln

@@ -52,6 +52,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SourceGeneratorTests", "tes
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "JsonApiDotNetCore.Annotations", "src\JsonApiDotNetCore.Annotations\JsonApiDotNetCore.Annotations.csproj", "{83FF097C-C8C6-477B-9FAB-DF99B84978B5}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DatabasePerTenantExample", "src\Examples\DatabasePerTenantExample\DatabasePerTenantExample.csproj", "{60334658-BE51-43B3-9C4D-F2BBF56C89CE}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -266,6 +268,18 @@ Global
 		{83FF097C-C8C6-477B-9FAB-DF99B84978B5}.Release|x64.Build.0 = Release|Any CPU
 		{83FF097C-C8C6-477B-9FAB-DF99B84978B5}.Release|x86.ActiveCfg = Release|Any CPU
 		{83FF097C-C8C6-477B-9FAB-DF99B84978B5}.Release|x86.Build.0 = Release|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Debug|x64.Build.0 = Debug|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Debug|x86.Build.0 = Debug|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Release|Any CPU.Build.0 = Release|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Release|x64.ActiveCfg = Release|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Release|x64.Build.0 = Release|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Release|x86.ActiveCfg = Release|Any CPU
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -288,6 +302,7 @@ Global
 		{87D066F9-3540-4AC7-A748-134900969EE5} = {24B15015-62E5-42E1-9BA0-ECE6BE7AA15F}
 		{0E0B5C51-F7E2-4F40-A4E4-DED0E9731DC9} = {24B15015-62E5-42E1-9BA0-ECE6BE7AA15F}
 		{83FF097C-C8C6-477B-9FAB-DF99B84978B5} = {7A2B7ADD-ECB5-4D00-AA6A-D45BD11C97CF}
+		{60334658-BE51-43B3-9C4D-F2BBF56C89CE} = {026FBC6C-AF76-4568-9B87-EC73457899FD}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {A2421882-8F0A-4905-928F-B550B192F9A4}

JsonApiDotNetCore.sln.DotSettings

@@ -631,6 +631,7 @@ $left$ = $right$;</s:String>
 	<s:String x:Key="/Default/PatternsAndTemplates/StructuralSearch/Pattern/=B3D9EE6B4EC62A4F961EB15F9ADEC2C6/Severity/@EntryValue">WARNING</s:String>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=appsettings/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Assignee/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Contoso/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Injectables/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=jsonapi/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=linebreaks/@EntryIndexedValue">True</s:Boolean>

src/Examples/DatabasePerTenantExample/Controllers/EmployeesController.cs

@@ -0,0 +1,15 @@
+using JsonApiDotNetCore.Controllers.Annotations;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DatabasePerTenantExample.Controllers;
+
+// Workaround for https://youtrack.jetbrains.com/issue/RSRP-487028
+public partial class EmployeesController
+{
+}
+
+[DisableRoutingConvention]
+[Route("api/{tenantName}/employees")]
+partial class EmployeesController
+{
+}

src/Examples/DatabasePerTenantExample/Data/AppDbContext.cs

@@ -0,0 +1,80 @@
+using System.Net;
+using DatabasePerTenantExample.Models;
+using JetBrains.Annotations;
+using JsonApiDotNetCore.Errors;
+using JsonApiDotNetCore.Serialization.Objects;
+using Microsoft.EntityFrameworkCore;
+
+namespace DatabasePerTenantExample.Data;
+
+[UsedImplicitly(ImplicitUseTargetFlags.Members)]
+public sealed class AppDbContext : DbContext
+{
+    private readonly IHttpContextAccessor _httpContextAccessor;
+    private readonly IConfiguration _configuration;
+    private string? _forcedTenantName;
+
+    public DbSet<Employee> Employees => Set<Employee>();
+
+    public AppDbContext(IHttpContextAccessor httpContextAccessor, IConfiguration configuration)
+    {
+        _httpContextAccessor = httpContextAccessor;
+        _configuration = configuration;
+    }
+
+    public void SetTenantName(string tenantName)
+    {
+        _forcedTenantName = tenantName;
+    }
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+        string connectionString = GetConnectionString();
+        optionsBuilder.UseNpgsql(connectionString);
+    }
+
+    private string GetConnectionString()
+    {
+        string? tenantName = GetTenantName();
+        string connectionString = _configuration[$"Data:{tenantName ?? "Default"}Connection"];
+
+        if (connectionString == null)
+        {
+            throw GetErrorForInvalidTenant(tenantName);
+        }
+
+        string postgresPassword = Environment.GetEnvironmentVariable("PGPASSWORD") ?? "postgres";
+        return connectionString.Replace("###", postgresPassword);
+    }
+
+    private string? GetTenantName()
+    {
+        if (_forcedTenantName != null)
+        {
+            return _forcedTenantName;
+        }
+
+        if (_httpContextAccessor.HttpContext != null)
+        {
+            string? tenantName = (string?)_httpContextAccessor.HttpContext.Request.RouteValues["tenantName"];
+
+            if (tenantName == null)
+            {
+                throw GetErrorForInvalidTenant(null);
+            }
+
+            return tenantName;
+        }
+
+        return null;
+    }
+
+    private static JsonApiException GetErrorForInvalidTenant(string? tenantName)
+    {
+        return new JsonApiException(new ErrorObject(HttpStatusCode.BadRequest)
+        {
+            Title = "Missing or invalid tenant in URL.",
+            Detail = $"Tenant '{tenantName}' does not exist."
+        });
+    }
+}

src/Examples/DatabasePerTenantExample/DatabasePerTenantExample.csproj

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+  <PropertyGroup>
+    <TargetFramework>$(TargetFrameworkName)</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\JsonApiDotNetCore\JsonApiDotNetCore.csproj" />
+    <ProjectReference Include="..\..\JsonApiDotNetCore.SourceGenerators\JsonApiDotNetCore.SourceGenerators.csproj" OutputItemType="Analyzer"
+      ReferenceOutputAssembly="false" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="$(EFCoreVersion)" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="$(EFCorePostgresVersion)" />
+  </ItemGroup>
+</Project>

src/Examples/DatabasePerTenantExample/Models/Employee.cs

@@ -0,0 +1,19 @@
+using JetBrains.Annotations;
+using JsonApiDotNetCore.Resources;
+using JsonApiDotNetCore.Resources.Annotations;
+
+namespace DatabasePerTenantExample.Models;
+
+[UsedImplicitly(ImplicitUseTargetFlags.Members)]
+[Resource]
+public sealed class Employee : Identifiable<Guid>
+{
+    [Attr]
+    public string FirstName { get; set; } = null!;
+
+    [Attr]
+    public string LastName { get; set; } = null!;
+
+    [Attr]
+    public string CompanyName { get; set; } = null!;
+}

src/Examples/DatabasePerTenantExample/Program.cs

@@ -0,0 +1,58 @@
+using DatabasePerTenantExample.Data;
+using DatabasePerTenantExample.Models;
+using JsonApiDotNetCore.Configuration;
+using Microsoft.EntityFrameworkCore;
+
+WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
+
+// Add services to the container.
+
+builder.Services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
+builder.Services.AddDbContext<AppDbContext>(options => options.UseNpgsql());
+
+builder.Services.AddJsonApi<AppDbContext>(options =>
+{
+    options.Namespace = "api";
+    options.UseRelativeLinks = true;
+    options.SerializerOptions.WriteIndented = true;
+});
+
+WebApplication app = builder.Build();
+
+// Configure the HTTP request pipeline.
+
+app.UseRouting();
+app.UseJsonApi();
+app.MapControllers();
+
+await CreateDatabaseAsync(null, app.Services);
+await CreateDatabaseAsync("AdventureWorks", app.Services);
+await CreateDatabaseAsync("Contoso", app.Services);
+
+app.Run();
+
+static async Task CreateDatabaseAsync(string? tenantName, IServiceProvider serviceProvider)
+{
+    await using AsyncServiceScope scope = serviceProvider.CreateAsyncScope();
+    var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
+
+    if (tenantName != null)
+    {
+        dbContext.SetTenantName(tenantName);
+    }
+
+    await dbContext.Database.EnsureDeletedAsync();
+    await dbContext.Database.EnsureCreatedAsync();
+
+    if (tenantName != null)
+    {
+        dbContext.Employees.Add(new Employee
+        {
+            FirstName = "John",
+            LastName = "Doe",
+            CompanyName = tenantName
+        });
+
+        await dbContext.SaveChangesAsync();
+    }
+}

src/Examples/DatabasePerTenantExample/Properties/launchSettings.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "http://json.schemastore.org/launchsettings.json",
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:14147",
+      "sslPort": 44340
+    }
+  },
+  "profiles": {
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "launchUrl": "api/AdventureWorks/employees",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "Kestrel": {
+      "commandName": "Project",
+      "launchBrowser": true,
+      "launchUrl": "api/AdventureWorks/employees",
+      "applicationUrl": "https://localhost:44347;http://localhost:14147",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

src/Examples/DatabasePerTenantExample/appsettings.json

@@ -0,0 +1,15 @@
+{
+  "Data": {
+    "DefaultConnection": "Host=localhost;Port=5432;Database=DefaultTenantDb;User ID=postgres;Password=###",
+    "AdventureWorksConnection": "Host=localhost;Port=5432;Database=AdventureWorks;User ID=postgres;Password=###",
+    "ContosoConnection": "Host=localhost;Port=5432;Database=Contoso;User ID=postgres;Password=###"
+  },
+  "Logging": {
+    "LogLevel": {
+      "Default": "Warning",
+      "Microsoft.Hosting.Lifetime": "Information",
+      "Microsoft.EntityFrameworkCore.Database.Command": "Information"
+    }
+  },
+  "AllowedHosts": "*"
+}