Fix ConnectionString forwarded improperly

src/Moryx.CommandCenter.Web/src/databases/container/DatabaseModel.tsx

@@ -377,7 +377,7 @@ class DatabaseModel extends React.Component<DatabaseModelPropsModel & DatabaseMo
                                 </Stack>
                             </GridLegacy>
                             <GridLegacy item={true} md={12}>
-                                <Button color="primary" onClick={() => this.onSave()}>Save</Button>
+                                <Button color="primary" variant="outlined" onClick={() => this.onSave()}>Save</Button>
                             </GridLegacy>
                         </DatabaseSection>
                         <DatabaseSection title="Backup &amp; Restore">

src/Moryx.Model.PostgreSQL/NpgsqlModelConfigurator.cs

@@ -6,6 +6,7 @@
 using System.Data.Common;
 using System.Diagnostics;
 using System.IO;
+using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
@@ -94,6 +95,41 @@ private static NpgsqlConnectionStringBuilder CreateConnectionStringBuilder(IData
             return builder;
         }
 
+        /// <summary>
+        /// Replaces given config's database with "postgres".
+        /// This config can be used to check availability of
+        /// the database server.
+        /// </summary>
+        /// <param name="config"></param>
+        /// <returns>Modified copy of given config</returns>
+        private static IDatabaseConfig CreateTestDatabaseConfig(IDatabaseConfig config)
+        {
+            var testConfig = new DatabaseConfig<DatabaseConnectionSettings>
+            {
+                ConfiguratorTypename = config.ConfiguratorTypename,
+                ConnectionSettings = config.ConnectionSettings,
+                ConfigState = config.ConfigState,
+                LoadError = config.LoadError
+            };
+
+            var builder = new NpgsqlConnectionStringBuilder(testConfig.ConnectionSettings.ConnectionString)
+            {
+                Database = "postgres"
+            };
+
+            testConfig.ConnectionSettings.ConnectionString = builder.ConnectionString;
+
+            return testConfig;
+        }
+
+        /// <inheritdoc/>
+        public override Task<TestConnectionResult> TestConnection(IDatabaseConfig config)
+        {
+            // Using the "postgres" database to check the server's availability.
+            // might lead to edge-case when "postgres" database has been deleted.
+            return base.TestConnection(CreateTestDatabaseConfig(config));
+        }
+
         /// <inheritdoc />
         public override Task RestoreDatabase(IDatabaseConfig config, string filePath)
         {