Integrating Mellon.MultiTenant with Hangfire in ASP.NET Core

[ShahramNo]

Hi,
I'm trying to integrate Mellon.MultiTenant into my existing multi-tenant setup with Hangfire. Could you provide guidance or examples on how to properly configure Mellon.MultiTenant with Hangfire? Specifically, I'm looking for help on how to ensure that Hangfire uses the correct connection string for each tenant.
I have 2 connection strings, Web is my default connection string when a tenant is not available, and Tenant stores all connection strings for every tenant, and i store all tenant in database,

Thank you in advance for your assistance!

appsetting:

{ "ConnectionStrings": { "Web": "Server=xxxx", "Tenant": "Server=xxx" } }

TenantModel:

`
```
public class Tenant : BaseEntity
{
public Guid Id { get; set; }
public string Name { get; set; }
public string? Host { get; set; }
public string SubDomain { get; set; } = null!;
public string ConnectionString { get; set; }
}

`

ITenantService:

` ```
 public interface ITenantService
   {
    Task IdentifyTenant(HttpContext context);
    Task<IEnumerable<Entities.Tenant.Tenant>> GetAllTenantsAsync();
    IEnumerable<Entities.Tenant.Tenant> GetAllTenants();
    Guid? GetTenantId(HttpContext context);
    string? GetTenantIdString(HttpContext context);
    Task<Entities.Tenant.Tenant> CreateTenantAsync(Entities.Tenant.Tenant tenant);
    Task<Entities.Tenant.Tenant> GetTenantByIdAsync(Guid id);
    string GetTenantConnectionString(HttpContext context);
    Task<Entities.Tenant.Tenant> GetCurrentTenantAsync(HttpContext context);
    void SetTenant(Entities.Tenant.Tenant tenant);
    string GetCurrentTenantConnectionString();
    Guid GetCurrentTenantId();
    string GetCurrentTenantIdString();
    Entities.Tenant.Tenant GetCurrentTenant();
    Task<Entities.Tenant.Tenant> GetCurrentTenantAsyncCaching(HttpContext context);
    string GetConnectionStringByTenantId(Guid tenantId);
    string GetDatabaseProvider();
    }

TenantResolutionMiddleware:

app.UseMiddleware<TenantResolutionMiddleware>();

` public class TenantResolutionMiddleware
{
private readonly RequestDelegate _next;

public TenantResolutionMiddleware(RequestDelegate next)
{
    _next = next;
}

public async Task InvokeAsync(HttpContext context, ITenantService tenantService)
{
    try
    {
        await tenantService.IdentifyTenant(context);
        var tenant = await tenantService.GetCurrentTenantAsync(context);
        if (tenant != null)
        {
            context.Items["ConnectionString"] = tenant.ConnectionString;
            context.Items["TenantConnectionString"] = tenant.ConnectionString;
            context.Items["TenantId"] = tenant.Id;
        }
        else
        {
            var defaultConnectionString = context.RequestServices.GetRequiredService<IConfiguration> 
                    ().GetConnectionString("Web");
            context.Items["ConnectionString"] = defaultConnectionString;
            context.Items["TenantConnectionString"] = defaultConnectionString;
        }
    }
    catch (Exception ex)
    {
        context.Response.StatusCode = 500; // Internal Server Error
        await context.Response.WriteAsync("An error occurred while identifying the tenant.");
        return;
    }
    await _next(context);
}

}`

InitializeTenantDatabases Middleware:

app.InitializeTenantDatabase(); app.InitializeTenantDatabases();

`public static class TenantDatabaseInitializer
{
public static void InitializeTenantDatabases(this WebApplication app)
{
using var scope = app.Services.CreateScope();
var tenantService = scope.ServiceProvider.GetRequiredService();

    var tenants = tenantService.GetAllTenants();

    foreach (var tenant in tenants)
    {
        using var tenantScope = app.Services.CreateScope();
        var dbContext = tenantScope.ServiceProvider.GetRequiredService<ApplicationDbContext>();

        dbContext.Database.SetConnectionString(tenant.ConnectionString);
        dbContext.Database.Migrate();

        var dataInitializers = tenantScope.ServiceProvider.GetServices<IDataInitializer>();
        foreach (var dataInitializer in dataInitializers)
            dataInitializer.InitializeData();
    }
}

public static IApplicationBuilder InitializeTenantDatabase(this IApplicationBuilder app)
{
    using var scope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope();
    var dbContext = scope.ServiceProvider.GetService<TenantDbContext>(); // Service locator
    dbContext.Database.Migrate();
    return app;
}

}
`
Tenant Services:

builder.Services.AddTenantServices(builder.Configuration); builder.Services.AddDynamicDbContexts(builder.Configuration);

`public static class ServiceCollectionExtensions
{
public static IServiceCollection AddTenantServices(this IServiceCollection services, IConfiguration configuration)
{
services.AddDbContext(options =>
options.UseSqlServer(configuration.GetConnectionString("Tenant")));

    services.AddScoped<ITenantService, TenantService>();
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
    services.AddMemoryCache();
    services.AddLogging();

    return services;
}

public static IServiceCollection AddDynamicDbContexts(this IServiceCollection services, IConfiguration configuration)
{
    services.AddHttpContextAccessor();
    services.AddDbContext<ApplicationDbContext>((serviceProvider, options) =>
    {
        var httpContextAccessor = serviceProvider.GetRequiredService<IHttpContextAccessor>();
        var connectionString = httpContextAccessor.HttpContext?.Items["ConnectionString"] as string
                              ?? configuration.GetConnectionString("Web");
        options.UseSqlServer(connectionString);
    });

    return services;
}

}`

[1bberto]

Currently, there is no way to load the tenants from a database, I was thinking about adding this feature, might be a good time to do so...😍

To use Hangfire with Mellon, you need only to do a few things

during the services configuration

builder.Services
        .AddMultiTenant()
        .AddMultiTenantHangfire();

builder.Services.AddHangfire((serviceProvider, config) =>
{
    // some code
    config.UseMultiTenant(serviceProvider);
    // some code
});

and you will have two options
have one queue per tenant, or not

if you want to have one queue per tenant you will need to create a Job interface like this

[Queue("tenant-name")]
public interface IMySuperNiceJob
{

}

this will move the job when is about to be executed to a queue with the tenant name

if not, once the job is created, the library will add a property to the job indicating the tenant for that particular job execution and all services will respect that accordingly

PS: sorry for the delay @ShahramNo...

[1bberto]

I created this issue here to address your request @ShahramNo
#30

[ShahramNo]

Hi,

Thank you for the detailed explanation. I have a follow-up question regarding loading tenants from a database. Given my current setup where I store all tenant information in a database, how can I configure Mellon.MultiTenant to dynamically load and manage tenants with Hangfire, ensuring that each tenant's specific connection string is used?

Here's a brief overview of my setup:

Connection Strings:

{ "ConnectionStrings": { "Web": "Server=xxxx", "Tenant": "Server=xxx" } }

Tenant Model:

`
public class Tenant : BaseEntity
{

    public Guid Id { get; set; }
    public string Name { get; set; }
    public string? Host { get; set; }
    public string SubDomain { get; set; } = null!;
    public string ConnectionString { get; set; }
}

`
Tenant Service Interface:

`

 public interface ITenantService
{
    Task IdentifyTenant(HttpContext context);

Task<IEnumerable<Entities.Tenant.Tenant>> GetAllTenantsAsync();
IEnumerable<Entities.Tenant.Tenant> GetAllTenants();
Guid? GetTenantId(HttpContext context);
string? GetTenantIdString(HttpContext context);
Task<Entities.Tenant.Tenant> CreateTenantAsync(Entities.Tenant.Tenant tenant);
Task<Entities.Tenant.Tenant> GetTenantByIdAsync(Guid id);
string GetTenantConnectionString(HttpContext context);
Task<Entities.Tenant.Tenant> GetCurrentTenantAsync(HttpContext context);
void SetTenant(Entities.Tenant.Tenant tenant);
string GetCurrentTenantConnectionString();
Guid GetCurrentTenantId();
string GetCurrentTenantIdString();
Entities.Tenant.Tenant GetCurrentTenant();
Task<Entities.Tenant.Tenant> GetCurrentTenantAsyncCaching(HttpContext context);
string GetConnectionStringByTenantId(Guid tenantId);
string GetDatabaseProvider();

}
`

Tenant Resolution Middleware:
`
app.UseMiddleware();

public class TenantResolutionMiddleware
{
private readonly RequestDelegate _next;

public TenantResolutionMiddleware(RequestDelegate next)
{
    _next = next;
}

public async Task InvokeAsync(HttpContext context, ITenantService tenantService)
{
    try
    {
        await tenantService.IdentifyTenant(context);
        var tenant = await tenantService.GetCurrentTenantAsync(context);
        if (tenant != null)
        {
            context.Items["ConnectionString"] = tenant.ConnectionString;
            context.Items["TenantConnectionString"] = tenant.ConnectionString;
            context.Items["TenantId"] = tenant.Id;
        }
        else
        {
            var defaultConnectionString = context.RequestServices.GetRequiredService<IConfiguration>().GetConnectionString("Web");
            context.Items["ConnectionString"] = defaultConnectionString;
            context.Items["TenantConnectionString"] = defaultConnectionString;
        }
    }
    catch (Exception ex)
    {
        context.Response.StatusCode = 500; // Internal Server Error
        await context.Response.WriteAsync("An error occurred while identifying the tenant.");
        return;
    }
    await _next(context);
}

}

`

Tenant Database Initializer:

`
app.InitializeTenantDatabase();
app.InitializeTenantDatabases();

public static class TenantDatabaseInitializer
{
public static void InitializeTenantDatabases(this WebApplication app)
{
using var scope = app.Services.CreateScope();
var tenantService = scope.ServiceProvider.GetRequiredService();

    var tenants = tenantService.GetAllTenants();

    foreach (var tenant in tenants)
    {
        using var tenantScope = app.Services.CreateScope();
        var dbContext = tenantScope.ServiceProvider.GetRequiredService<ApplicationDbContext>();

        dbContext.Database.SetConnectionString(tenant.ConnectionString);
        dbContext.Database.Migrate();

        var dataInitializers = tenantScope.ServiceProvider.GetServices<IDataInitializer>();
        foreach (var dataInitializer in dataInitializers)
            dataInitializer.InitializeData();
    }
}

public static IApplicationBuilder InitializeTenantDatabase(this IApplicationBuilder app)
{
    using var scope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope();
    var dbContext = scope.ServiceProvider.GetService<TenantDbContext>(); // Service locator
    dbContext.Database.Migrate();
    return app;
}

}

`

Service Configuration:

`
builder.Services.AddTenantServices(builder.Configuration);
builder.Services.AddDynamicDbContexts(builder.Configuration);

public static class ServiceCollectionExtensions
{
public static IServiceCollection AddTenantServices(this IServiceCollection services, IConfiguration configuration)
{
services.AddDbContext(options =>
options.UseSqlServer(configuration.GetConnectionString("Tenant")));

    services.AddScoped<ITenantService, TenantService>();
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
    services.AddMemoryCache();
    services.AddLogging();

    return services;
}

public static IServiceCollection AddDynamicDbContexts(this IServiceCollection services, IConfiguration configuration)
{
    services.AddHttpContextAccessor();
    services.AddDbContext<ApplicationDbContext>((serviceProvider, options) =>
    {
        var httpContextAccessor = serviceProvider.GetRequiredService<IHttpContextAccessor>();
        var connectionString = httpContextAccessor.HttpContext?.Items["ConnectionString"] as string
                              ?? configuration.GetConnectionString("Web");
        options.UseSqlServer(connectionString);
    });

    return services;
}

}

`

Given this setup, how can I implement Mellon.MultiTenant to dynamically load tenants from the database and ensure that Hangfire uses the correct connection string for each tenant? Is this currently possible with Mellon.MultiTenant, and if so, could you provide an example or additional guidance?

Thank you in advance for your assistance!