Table of Contents

BytLabs.Multitenancy

Tenant resolution primitives. Resolves a TenantId from the current request through a chain of pluggable resolvers; the data-access layer uses it to select a per-tenant database (database-per-tenant isolation).

Install

<PackageReference Include="BytLabs.Multitenancy" />

What's inside

Type Purpose
TenantId Immutable tenant identifier (string Value)
ITenantIdProvider TenantId GetTenantId() — the resolved current tenant
ITenantIdResolver bool TryGetCurrent(out TenantId?) — one resolution strategy
MultitenancyBuilder Fluent registration of resolvers (AddResolver<T>(), instance, or factory)
ValueTenantIdResolver Returns a fixed tenant (testing / fallback)
AddMultitenancy() Registers the provider and returns the builder
FailedToResolveTenantIdException Thrown when no resolver can identify the tenant

How it works

TenantIdProvider tries each registered ITenantIdResolver in order and returns the first TenantId found; if none succeed it throws FailedToResolveTenantIdException. Resolver exceptions are logged and skipped.

Usage

Registered for you by BytLabs.Api's WithMultiTenantContext:

.WithMultiTenantContext(mt => mt.AddResolver<FromHeaderTenantIdResolver>())

Or directly on a service collection:

services.AddMultitenancy()
    .AddResolver<FromHeaderTenantIdResolver>()              // from BytLabs.Api: reads a request header
    .AddResolver(sp => new ValueTenantIdResolver(new TenantId("bytlabs"))); // fallback

Consume the resolved tenant:

public class Foo(ITenantIdProvider tenants)
{
    public void Bar() { TenantId tenant = tenants.GetTenantId(); /* ... */ }
}

Custom resolver

public class FromClaimTenantIdResolver(IHttpContextAccessor http) : ITenantIdResolver
{
    public bool TryGetCurrent([NotNullWhen(true)] out TenantId? tenantId)
    {
        var value = http.HttpContext?.User.FindFirst("tenant")?.Value;
        tenantId = string.IsNullOrEmpty(value) ? null : new TenantId(value);
        return tenantId is not null;
    }
}

Where the tenant is used

BytLabs.DataAccess.MongoDB resolves IMongoDatabase per request as "{DatabaseName}-{tenantId}", so tenant isolation is physical and transparent — no tenant field on entities, no per-query filter. Tests/clients select the tenant by sending the resolver's header (e.g. Tenant: Test).

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