Determine connection string by current tenant. Resolved #12.

src/Volo.Abp.MultiTenancy/Volo/Abp/Data/MultiTenancy/ITenantConnectionStringStore.cs

@@ -0,0 +1,10 @@
+using JetBrains.Annotations;
+
+namespace Volo.Abp.Data.MultiTenancy
+{
+    public interface ITenantConnectionStringStore
+    {
+        [CanBeNull]
+        string GetConnectionStringOrNull([NotNull] string tenantId, [CanBeNull] string databaseName);
+    }
+}

src/Volo.Abp.MultiTenancy/Volo/Abp/Data/MultiTenancy/MultiTenantConnectionStringResolver.cs

@@ -0,0 +1,43 @@
+using Microsoft.Extensions.Options;
+using Volo.Abp.MultiTenancy;
+using Volo.DependencyInjection;
+
+namespace Volo.Abp.Data.MultiTenancy
+{
+    //TODO: It would be better to use composition over inheritance on connection string resolve progress!
+    //TODO: Create a replace service registration convention, instead of custom registration in AbpMultiTenancyModule?
+
+    [DisableConventionalRegistration]
+    public class MultiTenantConnectionStringResolver : DefaultConnectionStringResolver
+    {
+        private readonly IMultiTenancyManager _multiTenancyManager;
+        private readonly ITenantConnectionStringStore _tenantConnectionStringStore;
+
+        public MultiTenantConnectionStringResolver(
+            IOptions<DbConnectionOptions> options,
+            IMultiTenancyManager multiTenancyManager, 
+            ITenantConnectionStringStore tenantConnectionStringStore)
+            : base(options)
+        {
+            _multiTenancyManager = multiTenancyManager;
+            _tenantConnectionStringStore = tenantConnectionStringStore;
+        }
+
+        public override string Resolve(string databaseName = null)
+        {
+            var tenant = _multiTenancyManager.CurrentTenant;
+            if (tenant == null)
+            {
+                return base.Resolve(databaseName);
+            }
+
+            var connectionString = _tenantConnectionStringStore.GetConnectionStringOrNull(tenant.Id, databaseName);
+            if (connectionString == null)
+            {
+                return base.Resolve(databaseName);
+            }
+
+            return connectionString;
+        }
+    }
+}

src/Volo.Abp.MultiTenancy/Volo/Abp/Data/MultiTenancy/NullTenantConnectionStringStore.cs

@@ -0,0 +1,13 @@
+using Volo.DependencyInjection;
+
+namespace Volo.Abp.Data.MultiTenancy
+{
+    public sealed class NullTenantConnectionStringStore : ITenantConnectionStringStore, ISingletonDependency
+    {
+        public string GetConnectionStringOrNull(string tenantId, string databaseName)
+        {
+            //No tenant specific connection string by default
+            return null;
+        }
+    }
+}

src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/AbpMultiTenancyModule.cs

@@ -1,4 +1,7 @@
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Volo.Abp.Data;
+using Volo.Abp.Data.MultiTenancy;
 using Volo.Abp.Modularity;
 
 namespace Volo.Abp.MultiTenancy
@@ -7,6 +10,7 @@ namespace Volo.Abp.MultiTenancy
     {
         public override void ConfigureServices(IServiceCollection services)
         {
+            services.Replace(ServiceDescriptor.Transient<IConnectionStringResolver, MultiTenantConnectionStringResolver>());
             services.AddAssemblyOf<AbpMultiTenancyModule>();
         }
     }

src/Volo.Abp.TestBase/AbpIntegratedTest.cs

@@ -17,7 +17,7 @@ namespace Volo.Abp.TestBase
         {
             var services = CreateServiceCollection();
 
-            BeforeAppApplication(services);
+            BeforeAddApplication(services);
 
             Application = services.AddApplication<TStartupModule>();
 
@@ -33,7 +33,7 @@ namespace Volo.Abp.TestBase
             return new ServiceCollection();
         }
 
-        protected virtual void BeforeAppApplication(IServiceCollection services)
+        protected virtual void BeforeAddApplication(IServiceCollection services)
         {
 
         }

src/Volo.Abp/Volo/Abp/Data/DefaultConnectionStringResolver.cs

@@ -14,7 +14,7 @@ namespace Volo.Abp.Data
             _options = options.Value;
         }
 
-        public string Resolve(string databaseName = null)
+        public virtual string Resolve(string databaseName = null)
         {
             //TODO: Override by tenant conn string
             //TODO: Override by tenant module specific conn string

test/Volo.Abp.MultiTenancy.Tests/Volo/Abp/Data/MultiTenancy/MultiTenantConnectionStringResolver_Tests.cs

@@ -0,0 +1,95 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Options;
+using Shouldly;
+using Volo.Abp.MultiTenancy;
+using Xunit;
+
+namespace Volo.Abp.Data.MultiTenancy
+{
+    public class MultiTenantConnectionStringResolver_Tests : MultiTenancyTestBase
+    {
+        private readonly IMultiTenancyManager _multiTenancyManager;
+        private readonly IConnectionStringResolver _connectionResolver;
+
+        public MultiTenantConnectionStringResolver_Tests()
+        {
+            _multiTenancyManager = ServiceProvider.GetRequiredService<IMultiTenancyManager>();
+
+            _connectionResolver = ServiceProvider.GetRequiredService<IConnectionStringResolver>();
+            _connectionResolver.ShouldBeOfType<MultiTenantConnectionStringResolver>();
+        }
+
+        protected override void BeforeAddApplication(IServiceCollection services)
+        {
+            services.Configure<DbConnectionOptions>(options =>
+            {
+                options.ConnectionStrings.Default = "default-value";
+                options.ConnectionStrings["db1"] = "db1-default-value";
+                options.ConnectionStrings["tenant1#Default"] = "tenant1-default-value";
+                options.ConnectionStrings["tenant1#db1"] = "tenant1-db1-value";
+            });
+        }
+
+        protected override void AfterAddApplication(IServiceCollection services)
+        {
+            services.Replace(ServiceDescriptor.Transient<ITenantConnectionStringStore, MyTenantConnectionStringStore>());
+        }
+
+        [Fact]
+        public void All_Tests()
+        {
+            //No tenant in current context
+            _connectionResolver.Resolve().ShouldBe("default-value");
+            _connectionResolver.Resolve("db1").ShouldBe("db1-default-value");
+
+            //Overrided connection strings for tenant1
+            using (_multiTenancyManager.ChangeTenant(new TenantInfo("tenant1")))
+            {
+                _connectionResolver.Resolve().ShouldBe("tenant1-default-value");
+                _connectionResolver.Resolve("db1").ShouldBe("tenant1-db1-value");
+            }
+
+            //No tenant in current context
+            _connectionResolver.Resolve().ShouldBe("default-value");
+            _connectionResolver.Resolve("db1").ShouldBe("db1-default-value");
+
+            //Undefined connection strings for tenant2
+            using (_multiTenancyManager.ChangeTenant(new TenantInfo("tenant2")))
+            {
+                _connectionResolver.Resolve().ShouldBe("default-value");
+                _connectionResolver.Resolve("db1").ShouldBe("db1-default-value");
+            }
+        }
+
+        public class MyTenantConnectionStringStore : ITenantConnectionStringStore
+        {
+            private readonly IOptions<DbConnectionOptions> _options;
+
+            public MyTenantConnectionStringStore(IOptions<DbConnectionOptions> options)
+            {
+                _options = options;
+            }
+
+            public string GetConnectionStringOrNull(string tenantId, string databaseName)
+            {
+                if (databaseName != null)
+                {
+                    if (_options.Value.ConnectionStrings.ContainsKey(tenantId + "#" + databaseName))
+                    {
+                        return _options.Value.ConnectionStrings[tenantId + "#" + databaseName];
+                    }
+                }
+                else
+                {
+                    if (_options.Value.ConnectionStrings.ContainsKey(tenantId + "#Default"))
+                    {
+                        return _options.Value.ConnectionStrings[tenantId + "#Default"];
+                    }
+                }
+
+                return null;
+            }
+        }
+    }
+}