.Net Core 动态 dbContext

Question

I has two DbContext sharing the same repository. The following is my existing codes:

Startup.cs

        services.AddDbContext<SgAesMasterContext>(options =>  options.UseSqlServer(Configuration.GetConnectionString("SgAesMasterContext"),
            b => b.UseRowNumberForPaging()), ServiceLifetime.Scoped);

        services.AddDbContext<MyAesMasterContext>(options => options.UseSqlServer(Configuration.GetConnectionString("MyAesMasterContext"),
            b => b.UseRowNumberForPaging()), ServiceLifetime.Scoped);

DbContext.cs

public class SgAesMasterContext : DbContext
{
    public DbSet<Company> Companies { get; set; }

    public SgAesMasterContext(DbContextOptions<SgAesMasterContext> options) : base(options) { }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
    }
}

public class MyAesMasterContext : DbContext
{
    public DbSet<Company> Companies { get; set; }

    public MyAesMasterContext(DbContextOptions<MyAesMasterContext> options) : base(options) { }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
    }
}

UnitOfWork.cs

public class AesMasterUnitOfWork: IAesMasterUnitOfWork
{
    private readonly SgAesMasterContext sgAesMasterContext;
    private readonly MyAesMasterContext myAesMasterContext;

    public AesMasterUnitOfWork(SgAesMasterContext sgAesMasterContext, MyAesMasterContext myAesMasterContext)
    {
        this.sgAesMasterContext = sgAesMasterContext;
        this.myAesMasterContext = myAesMasterContext;
    }

    public SgAesMasterContext SgAesMasterContext { get { return sgAesMasterContext; } }
    public MyAesMasterContext MyAesMasterContext { get { return myAesMasterContext; } }
    public CompanyRepository CompanyRepo { get { return new CompanyRepository(sgAesMasterContext, myAesMasterContext); } }

    public void Dispose()
    {
        sgAesMasterContext.Dispose();
        myAesMasterContext.Dispose();
    }
}

CompanyRepository.cs

public class CompanyRepository
{
    protected readonly SgAesMasterContext sgAesMasterContext;
    protected readonly MyAesMasterContext myAesMasterContext;

    public CompanyRepository(SgAesMasterContext sgAesMasterContext, MyAesMasterContext myAesMasterContext)
    {
        this.sgAesMasterContext = sgAesMasterContext;
        this.myAesMasterContext = myAesMasterContext;
    }

    public async Task<List<Company>> GetCompanies(string country)
    {
        List<Company> companies = new List<Company>();

        switch (country)
        {
            case "SG":
                companies = await sgAesMasterContext.Companies.Where(x => x.Company_Status == "A" && x.Status == "0").ToListAsync();
                break;
            case "MY":
                companies = await myAesMasterContext.Companies.Where(x => x.Company_Status == "A" && x.Status == "0").ToListAsync();
                break;
        }

        return companies;
    }
}

Is there any solution that I can make my repository to call a dynamic DbContext instead of using switch case? This is because if I using switch case for every function in my repository, it will become redundant and difficult to maintain.

Answer 1

This solution is good for multi-tenant types of scenarios, where you have same schema and need to run same query but on different databases based on the tenant.

You can have a single DbContext but pass ConnectionString dynamically to connect to different databases.

Since you have only one DbContext all your repository will depend on that DbContext. Though you need to pass the correct connection string to DbContext based on tenant.

you can create and implement ITenantDbContextFactory which will look into request to identify which ConnectionString to use and create DbContext based on that

setup ITenantDbContextFactory in depedency injection

public class TenantDbContextFactory : ITenantDbContextFactory 
{
       public TenantDbContext GetDbContext()
       {
             string country;
               // Read Request to identify correct tenant
             switch (country)
             {
                 case "SG":
                      return new TenantDbContext("connectionstring for Sg")
                break;
                 case "MY":
                      return new TenantDbContext("connectionstring for my")
                break;
             }
       }
}

public class TenantDbContext: DbContext
{
    public DbSet<Company> Companies { get; set; }

    public TenantDbContext(DbContextOptions<TenantDbContext> options) : base(options) { }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
    }
}

public class TenantUnitOfWork: ITenantUnitOfWork
{
    private readonly TenantDbContext tenantDbContext;

    public TenantUnitOfWork(ITenantDbContextFactory tenantDbContextFactory)
    {
        this.tenantDbContext= tenantDbContextFactory.GetDbContext();
    }

    public TenantDbContext  TenantDbContext  { get { return tenantDbContext; } }
    public CompanyRepository CompanyRepo { get { return new CompanyRepository(tenantDbContext); } }

    public void Dispose()
    {
        tenantDbContext.Dispose();
    }
}

public class CompanyRepository
{
    protected readonly TenantDbContext tenantDbContext ;

    public CompanyRepository(TenantDbContext tenantDbContext)
    {
        this.tenantDbContext = tenantDbContext ;
    }

    public async Task<List<Company>> GetCompanies()
    {
        List<Company> companies = new List<Company>();

        companies = await tenantDbContext.Companies.Where(x => x.Company_Status == "A" && x.Status == "0").ToListAsync();

        return companies;
    }
}