Initial database connectors code

Author: basjam

DBAccess.csproj

@@ -6,4 +6,8 @@
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Npgsql" Version="6.0.6" />
+  </ItemGroup>
+
 </Project>

DatabaseConnectors/IDatabaseConnector.cs

@@ -0,0 +1,10 @@
+namespace DBAccess.DatabaseConnectors
+{
+    public interface IDatabaseConnector
+    {
+        public string? GetDatabaseVersion(string? host, string databaseName, string databasePort);
+        public string? ExecuteSQL(string SQLQuery);
+        public string? GetTables();
+
+    }
+}

DatabaseConnectors/PostgresConnector.cs

@@ -0,0 +1,86 @@
+using System.Data.Common;
+using Npgsql;
+
+namespace DBAccess.DatabaseConnectors
+{
+    public class PostgresConnector : IDatabaseConnector
+    {
+        private static string? dbUsername = Environment.GetEnvironmentVariable("DB_USERNAME");
+        private static string? dbPassword = Environment.GetEnvironmentVariable("DB_PASSWORD");
+        private NpgsqlConnection? connection;
+
+        public PostgresConnector(string? host, string? databaseName, string? databasePort)
+        {
+            host = (host == null) ? "localhost" : host;
+            databaseName = (databaseName == null) ? "postgres" : databaseName;
+            databasePort = (databasePort == null) ? "5432" : databasePort;
+
+            var connectionString = buildConnectionString(host, dbUsername, dbPassword, databaseName, databasePort);
+            try
+            {
+                ConnectToDatabase(connectionString);
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine(e.Message);
+            }
+
+        }
+
+        public string GetTables()
+        {
+            var sqlQuerry = "select * from pg_catalog.pg_tables where schemaname != 'pg_catalog' and schemaname != 'information_schema';";
+            return ExecuteSQL(sqlQuerry);
+        }
+        public static string? GetUsername()
+        {
+            return dbUsername;
+        }
+
+        public string? GetDatabaseVersion(string? host, string databaseName, string databasePort)
+        {
+
+            var sqlQuery = "SELECT version()";
+
+            return ExecuteSQL(sqlQuery);
+        }
+
+        public string ExecuteSQL(string SQLQuery)
+        {
+            using var command = new NpgsqlCommand(SQLQuery, connection);
+            string? queryResult = "";
+            try
+            {
+                if (command.ExecuteScalar() != null &&
+                    connection != null)
+                {
+                    queryResult = command.ExecuteScalar().ToString();
+                }
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine(e.Message);
+                return e.Message;
+            }
+
+
+            return queryResult;
+        }
+
+        private void ConnectToDatabase(string connectionString)
+        {
+            connection = new NpgsqlConnection(connectionString);
+            connection.Open();
+        }
+
+        private string buildConnectionString(string host, string? username, string? password, string databaseName, string databasePort)
+        {
+            string usernameConstruct =
+                username == null ? "" : $"Username={username};";
+            string passwordConstruct =
+                password == null ? "" : $"Password={password};";
+            return $"Host={host};{usernameConstruct}{passwordConstruct}Database={databaseName};Port={databasePort}";
+        }
+
+    }
+}

Pages/Databases.razor

@@ -0,0 +1,49 @@
+@page "/databases"
+
+<PageTitle>Databases</PageTitle>
+
+
+<h1>Databases</h1>
+UserName: @username
+
+<p>
+    <label>Host</label><input type="text" name="host" @bind="host">
+</p>
+<p>
+    <label>DB Name</label><input type="text" name="databaseName" @bind="databaseName">
+</p>
+<p>
+    <label>DB Port</label><input type="text" name="databasePort" @bind="databasePort">
+</p>
+<p>
+    <button @onclick="connectToDatabase"> Connect to database</button>
+</p>
+
+<p>
+    <label>Database Version: @dbVersion</label>
+</p>
+<p>
+    <label>Tables: @tables</label>
+</p>
+
+
+
+
+
+@code {
+    private string host = "localhost";
+    private string databaseName = "testdb";
+    private string databasePort = "5000";
+    private PostgresConnector connector;
+    private string? dbVersion;
+    private string? tables;
+    private void connectToDatabase() 
+    {
+        connector = new PostgresConnector(host, databaseName, databasePort);
+        dbVersion = connector.GetDatabaseVersion(host, databaseName, databasePort);
+        tables = connector.GetTables();
+    }
+    private string? username = PostgresConnector.GetUsername();
+
+}
+

Program.cs

@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.Components.Web;
 using DBAccess.Data;
+using DBAccess.DatabaseConnectors;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -29,3 +30,4 @@
 app.MapFallbackToPage("/_Host");
 
 app.Run();
+

Shared/NavMenu.razor

@@ -24,6 +24,11 @@
                 <span class="oi oi-list-rich" aria-hidden="true"></span> Fetch data
             </NavLink>
         </div>
+        <div class="nav-item px-3">
+            <NavLink class="nav-link" href="databases">
+                <span class="oi oi-list-rich" aria-hidden="true"></span> Databases
+            </NavLink>
+        </div>
     </nav>
 </div>
 

_Imports.razor

@@ -8,3 +8,4 @@
 @using Microsoft.JSInterop
 @using DBAccess
 @using DBAccess.Shared
+@using DBAccess.DatabaseConnectors