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