afonsoft/abp-multi-tenancy

ABP Multi-Tenancy

Docs: https://abp.io/docs/latest/framework/architecture/multi-tenancy

Making Entities Multi-Tenant

Implement IMultiTenant interface to make entities tenant-aware:

public class Product : AggregateRoot<Guid>, IMultiTenant
{
    public Guid? TenantId { get; set; } // Required by IMultiTenant

    public string Name { get; private set; }
    public decimal Price { get; private set; }

    protected Product() { }

    public Product(Guid id, string name, decimal price) : base(id)
    {
        Name = name;
        Price = price;
        // TenantId is automatically set from CurrentTenant.Id
    }
}

Key points:

• TenantId is nullable - null means entity belongs to Host
• ABP automatically filters queries by current tenant
• ABP automatically sets TenantId when creating entities

Accessing Current Tenant

Use CurrentTenant property (available in base classes) or inject ICurrentTenant:

public class ProductAppService : ApplicationService
{
    public async Task DoSomethingAsync()
    {
        // Available from base class
        var tenantId = CurrentTenant.Id;        // Guid? - null for host
        var tenantName = CurrentTenant.Name;    // string?
        var isAvailable = CurrentTenant.IsAvailable; // true if Id is not null
    }
}

// In other services
public class MyService : ITransientDependency
{
    private readonly ICurrentTenant _currentTenant;
    public MyService(ICurrentTenant currentTenant) => _currentTenant = currentTenant;
}

Switching Tenant Context

Use CurrentTenant.Change() to temporarily switch tenant (useful in host context):

public class ProductManager : DomainService
{
    private readonly IRepository<Product, Guid> _productRepository;

    public async Task<long> GetProductCountAsync(Guid? tenantId)
    {
        // Switch to specific tenant
        using (CurrentTenant.Change(tenantId))
        {
            return await _productRepository.GetCountAsync();
        }
        // Automatically restored to previous tenant after using block
    }

    public async Task DoHostOperationAsync()
    {
        // Switch to host context
        using (CurrentTenant.Change(null))
        {
            // Operations here are in host context
        }
    }
}

Important: Always use Change() with a using statement.

Disabling Multi-Tenant Filter

To query all tenants' data (only works with single database):

public class ProductManager : DomainService
{
    public async Task<long> GetAllProductCountAsync()
    {
        // DataFilter is available from base class
        using (DataFilter.Disable<IMultiTenant>())
        {
            return await _productRepository.GetCountAsync();
            // Returns count from ALL tenants
        }
    }
}

Note: This doesn't work with separate databases per tenant.

Database Architecture Options

| Approach | Description | Use Case | |----------|-------------|----------| | Single Database | All tenants share one database | Simple, cost-effective | | Database per Tenant | Each tenant has dedicated database | Data isolation, compliance | | Hybrid | Mix of shared and dedicated | Flexible, premium tenants |

Connection strings are configured per tenant in Tenant Management module.

Best Practices

1. Always implement IMultiTenant for tenant-specific entities
2. Never manually filter by TenantId - ABP does it automatically
3. Don't change TenantId after creation - it moves entity between tenants
4. Use Change() scope carefully - nested scopes are supported
5. Test both host and tenant contexts - ensure proper data isolation
6. Consider nullable TenantId - entity may be host-only or shared

Enabling Multi-Tenancy

Configure<AbpMultiTenancyOptions>(options =>
{
    options.IsEnabled = true; // Enabled by default in ABP templates
});

Check MultiTenancyConsts.IsEnabled in your solution for centralized control.

Tenant Resolution

ABP resolves current tenant from (in order):

1. Current user's claims
2. Query string (?__tenant=...)
3. Route (/{__tenant}/...)
4. HTTP header (__tenant)
5. Cookie (__tenant)
6. Domain/subdomain (if configured)

For subdomain-based resolution:

Configure<AbpTenantResolveOptions>(options =>
{
    options.AddDomainTenantResolver("{0}.mydomain.com");
});