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:

csharp

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:

csharp

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):

csharp

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):

csharp

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

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

Enabling Multi-Tenancy

csharp

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):

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

For subdomain-based resolution:

csharp

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