AJBurgess.MultiTenancy 1.0.0

Switching tenants

To change the current tenant, just call ChangeTenant(tenantId) on your DbContext. This has two effects:

1. All database queries are automatically filtered to include only data belonging to that tenant
2. Any new entities added, automatically belong to that tenant

using (MyDbContext context = new MyDbContext())
{
    // Create two tenants
    context.Tenants.Add(new Tenant { Id = "ACL", Name = "Acme Components Ltd" });
    context.Tenants.Add(new Tenant { Id = "RRS", Name = "Road Runner Supplies" });
    context.SaveChanges();

    // Switch to first tenant
    context.ChangeTenant("ACL");

    // Add some account entities, specific to the current tenant
    context.Accounts.Add(new Account { Name = "Dan's Dynamite" });
    context.Accounts.Add(new Account { Name = "Weighty Weights" });
    context.SaveChanges();

    // Switch to second tenant
    context.ChangeTenant("RRS");

    // Add some account entities, specific to the current tenant
    context.Accounts.Add(new Account { Name = "Fake Holes R Us" });
    context.SaveChanges();

    // The data is now stored like this:
    //
    // ACL
    //   |-> Dan's Dynamite
    //   |-> Weighty Weights
    //
    // RRS
    //   |-> Fake Holes R Us

    // Switch back to first tenant
    context.ChangeTenant("ACL");

    // Read the accounts (specific to the current tenant)
    List<Account> accounts = context.Accounts.ToList(); // 2 x accounts only

    // Switch back to second tenant
    context.ChangeTenant("RRS");

    // Read the accounts (specific to the current tenant)
    accounts = context.Accounts.ToList(); // 1 x account only
}

How does it work?

To enable this capability, you need to do several things:

1. Derive your DbContext class from EntityFramework.MultiTenantDbContext<TId>, where TId is the data type of the primary key of your tenant entity.
2. In your data model, have an entity that represents your concept of a tenant.
3. In every entity that is tenant-specific, have two properties: the foreign key ID of the parent tenant, and a navigation property for the tenant entity itself.

For example:

public class MyDbContext : MultiTenantDbContext<string>
{
    public DbSet<Tenant> Tenants { get; set; }
    public DbSet<Account> Accounts { get; set; }
    public DbSet<Transaction> Transactions { get; set; }

    public MyDbContext() : base("MultiTenancy.SampleApp")
    {
    }
}

public class Tenant
{
    [Key]
    [MaxLength(10)]
    [Required(AllowEmptyStrings = false)]
    public string Id { get; set; }

    [MaxLength(50)]
    public string Name { get; set; }
}

public class Account
{
    [Key]
    public int Id { get; private set; }

    [Required]
    public string TenantId { get; private set; }

    public virtual Tenant Tenant { get; set; }

    [MaxLength(50)]
    public string Name { get; set; }

    public virtual ICollection<Transaction> Transactions { get; set; }
}

public class Transaction
{
    [Key]
    public int Id { get; private set; }

    public int AccountId { get; set; }

    [Required]
    public virtual Account Account { get; set; }

    [Required]
    public string TenantId { get; private set; }

    public virtual Tenant Tenant { get; set; }

    [MaxLength(50)]
    public string Description { get; set; }
}

Further information

For further information, see the project wiki