Dotnet Oracle Wpf Integration

Add Oracle Database Connection to WPF Applications

End-to-end workflow for adding Oracle Database connection to existing .NET WPF applications: OracleConfigModel with DPAPI encryption, MVVM settings dialog with connection test, repository pattern for data access, and SQL execution with ORA-* error handling.

When to Use This Skill

Use this skill when:

• Adding Oracle Database connection to an existing WPF application
• Creating MVVM settings dialog for Oracle connection with connection test
• Implementing repository pattern (ISofRepository + SofDatabaseOracle) for Oracle
• Executing validated Oracle SQL from dotnet-access-to-oracle-migration
• Building data access layer with parameterized queries and connection pooling

Prerequisites:

• dotnet-wpf-secure-config must be applied first (DPAPI encryption foundation)
• Oracle SQL should be prepared using dotnet-access-to-oracle-migration (Access → Oracle conversion)

Related Skills

• dotnet-wpf-secure-config — Required: DPAPI encryption foundation (apply first)
• dotnet-access-to-oracle-migration — Convert Access SQL to Oracle SQL for use in Step 5
• dotnet-wpf-dify-api-integration — Shares SecureConfigService when used in the same app
• tdd-standard-practice — Test generated code with Red-Green-Refactor
• git-commit-practices — Commit each step as an atomic change

Core Principles

1. Layered Architecture — Separate Domain (ISofRepository), Infrastructure (SofDatabaseOracle), and Presentation (ViewModel) (基礎と型)
2. Security by Default — Passwords encrypted via DPAPI; connection strings built at runtime, never stored (ニュートラル)
3. Progressive Integration — Config → UI → Repository → SQL, one layer at a time (継続は力)
4. MVVM Discipline — ViewModel drives all UI logic; minimal code-behind (基礎と型)
5. Reusable Components — Repository and config patterns work across WPF projects (成長の複利)

Workflow: Integrate Oracle DB into WPF

Step 1 — Set Up Project Structure

Use when initializing the folder structure and NuGet dependencies for Oracle integration.

Add Oracle-specific folders to the existing project structure from dotnet-wpf-secure-config:

• Infrastructure/Configuration/OracleConfigModel.cs — Oracle config model
• Infrastructure/Repositories/ISofRepository.cs + SofDatabaseOracle.cs — Data access
• Presentation/ViewModels/OracleConfigViewModel.cs — Settings ViewModel
• Presentation/Views/OracleConfigDialog.xaml — Settings dialog

# Oracle data access provider
Install-Package Oracle.ManagedDataAccess.Core
# MVVM framework (skip if already installed from dotnet-wpf-secure-config)
Install-Package CommunityToolkit.Mvvm

Values: 基礎と型 / 成長の複利

Step 2 — Add Oracle Config Model

Use when defining the Oracle connection configuration with DPAPI-encrypted password.

Create OracleConfigModel and integrate it into the existing AppConfigModel from dotnet-wpf-secure-config.

OracleConfigModel.cs:

namespace YourApp.Infrastructure.Configuration
{
    public class OracleConfigModel
    {
        public string UserId { get; set; } = string.Empty;
        public string PasswordEncrypted { get; set; } = string.Empty;
        // EZ Connect format required: "host:port/service". Run tnsping to resolve TNS names.
        public string DataSource { get; set; } = string.Empty;

        public string GetDecryptedPassword()
            => DpapiEncryptor.Decrypt(PasswordEncrypted);
        public void SetPassword(string plainPassword)
            => PasswordEncrypted = DpapiEncryptor.Encrypt(plainPassword);
        public bool IsValid()
            => !string.IsNullOrWhiteSpace(UserId)
            && !string.IsNullOrWhiteSpace(PasswordEncrypted)
            && !string.IsNullOrWhiteSpace(DataSource);
    }
}

Update AppConfigModel (add Oracle property):

public class AppConfigModel
{
    public OracleConfigModel OracleDb { get; set; } = new();  // 🆕 Add this
    // public DifyConfigModel DifyApi { get; set; } = new();  // Added by Dify skill
    public string Version { get; set; } = "1.0";
}

Update ISecureConfigService and SecureConfigService (add Oracle methods):

// ISecureConfigService — add:
Task<OracleConfigModel> LoadOracleConfigAsync();
Task SaveOracleConfigAsync(OracleConfigModel config);

// SecureConfigService — implement:
public async Task<OracleConfigModel> LoadOracleConfigAsync()
{
    var appConfig = await LoadAppConfigAsync();
    return appConfig.OracleDb;
}
public async Task SaveOracleConfigAsync(OracleConfigModel config)
{
    var appConfig = await LoadAppConfigAsync();
    appConfig.OracleDb = config;
    await SaveAppConfigAsync(appConfig);
}

Values: 基礎と型 / ニュートラル

Step 3 — Create Settings UI

Use when building the Oracle connection settings dialog with connection test.

Create ViewModel and XAML dialog following MVVM pattern.

Key implementation points (full code → references/detailed-patterns.md):

• [ObservableProperty] for UserId, Password, DataSource, StatusMessage, IsSaving
• [RelayCommand] for SaveAsync and TestConnectionAsync
• Handle DPAPI decryption failure gracefully (password re-entry prompt)
• Connection test: SELECT SYSDATE FROM DUAL with 10-second timeout
• PasswordBox bridging in code-behind (WPF does not support binding natively)

Values: 基礎と型 / 成長の複利

Step 4 — Build Data Access Layer

Use when implementing the repository pattern for Oracle data access.

Create ISofRepository interface in the Domain layer and SofDatabaseOracle implementation in Infrastructure.

ISofRepository.cs — Domain interface (no Oracle dependency):

namespace YourApp.Infrastructure.Repositories
{
    public interface ISofRepository
    {
        // Returns rows as List<Dictionary<column_name, value>>
        Task<List<Dictionary<string, object?>>> QueryAsync(
            string sql, Dictionary<string, object>? parameters = null);
        // Returns affected row count
        Task<int> ExecuteAsync(
            string sql, Dictionary<string, object>? parameters = null);
    }
}

SofDatabaseOracle.cs — Infrastructure implementation:

using Oracle.ManagedDataAccess.Client;

namespace YourApp.Infrastructure.Repositories
{
    public class SofDatabaseOracle : ISofRepository
    {
        private readonly ISecureConfigService _configService;
        public SofDatabaseOracle(ISecureConfigService configService)
            => _configService = configService;

        public async Task<List<Dictionary<string, object?>>> QueryAsync(
            string sql, Dictionary<string, object>? parameters = null)
        {
            var results = new List<Dictionary<string, object?>>();
            await using var conn = await CreateConnectionAsync();
            await using var cmd = conn.CreateCommand();
            cmd.CommandText = sql;
            BindParameters(cmd, parameters);
            await using var reader = await cmd.ExecuteReaderAsync();
            while (await reader.ReadAsync())
            {
                var row = new Dictionary<string, object?>();
                for (int i = 0; i < reader.FieldCount; i++)
                    row[reader.GetName(i)] = reader.IsDBNull(i) ? null : reader.GetValue(i);
                results.Add(row);
            }
            return results;
        }

        public async Task<int> ExecuteAsync(
            string sql, Dictionary<string, object>? parameters = null)
        {
            await using var conn = await CreateConnectionAsync();
            await using var cmd = conn.CreateCommand();
            cmd.CommandText = sql;
            BindParameters(cmd, parameters);
            return await cmd.ExecuteNonQueryAsync();
        }

        private async Task<OracleConnection> CreateConnectionAsync()
        {
            var config = await _configService.LoadOracleConfigAsync();
            if (!config.IsValid())
                throw new InvalidOperationException(
                    "Oracle connection is not configured. Open Settings to enter credentials.");
            string password = config.GetDecryptedPassword();
            var conn = new OracleConnection(
                $"User Id={config.UserId};Password={password};Data Source={config.DataSource};");
            await conn.OpenAsync();
            return conn;
        }

        private static void BindParameters(
            OracleCommand cmd, Dictionary<string, object>? parameters)
        {
            if (parameters == null) return;
            // ✅ Always use parameterized queries — prevents SQL injection
            foreach (var (key, value) in parameters)
                cmd.Parameters.Add(new OracleParameter(key, value ?? DBNull.Value));
        }
    }
}

Why repository pattern: The domain layer depends on ISofRepository (an interface), not on OracleConnection (infrastructure). This allows testing with mock repositories and switching databases without changing business logic.

Values: 基礎と型 / 成長の複利

Step 5 — Implement SQL Execution

Use when executing validated Oracle SQL for CRUD operations.

Use ISofRepository methods with SQL from dotnet-access-to-oracle-migration.

SELECT query (read data):

// SQL validated by dotnet-access-to-oracle-migration
string sql = @"
SELECT s.""ship_date"", s.""prod_number"", s.""quantity""
FROM SCHEMA_A.""production_info"" s
WHERE s.""ship_date"" >= :shipDate";

var results = await _repository.QueryAsync(sql,
    new Dictionary<string, object> { { ":shipDate", "202601" } });

foreach (var row in results)
{
    string shipDate = row["ship_date"]?.ToString() ?? "";
    string prodNumber = row["prod_number"]?.ToString() ?? "";
}

INSERT/UPDATE/DELETE (write data with transaction):

await using var conn = new OracleConnection(connectionString);
await conn.OpenAsync();
await using var transaction = conn.BeginTransaction();
try
{
    await using var cmd = conn.CreateCommand();
    cmd.Transaction = transaction;
    cmd.CommandText = @"UPDATE SCHEMA_A.""production_info""
        SET ""status"" = :status WHERE ""prod_number"" = :prodNo";
    cmd.Parameters.Add(new OracleParameter(":status", "SHIPPED"));
    cmd.Parameters.Add(new OracleParameter(":prodNo", "P-001"));
    await cmd.ExecuteNonQueryAsync();
    await transaction.CommitAsync();
}
catch { await transaction.RollbackAsync(); throw; }

Oracle quoting rules (from dotnet-access-to-oracle-migration):

• Table names: SCHEMA_A."production_info" (schema + double-quoted lowercase)
• Column names: "ship_date" (double-quoted lowercase)
• String literals: '202601' (single quotes, not double)
• C# verbatim strings: @"s.""ship_date""" (double the double-quotes)

Values: 基礎と型 / 継続は力

Step 6 — Error Handling

Use when handling Oracle-specific errors from connection or query execution.

Map ORA-* error codes to actionable solutions. See Quick Reference for the full error code table.

catch (OracleException ex)
{
    string message = ex.Number switch
    {
        1017 => "Authentication failed. Check User ID and Password.",
        12154 => "TNS name not found. Use EZ Connect format (host:port/service).",
        12545 => "Network error. Check host, port, and firewall.",
        50201 => "Invalid Data Source format. Run tnsping to get EZ Connect string.",
        12170 => "Connection timeout. Check network or increase timeout.",
        _ => $"Oracle error ORA-{ex.Number:D5}: {ex.Message}"
    };
    throw new InvalidOperationException(message, ex);
}

TNS vs EZ Connect: Oracle.ManagedDataAccess.Core NuGet package cannot resolve ODBC DSN or TNS names. Run tnsping DSN_NAME to extract EZ Connect format (host:port/service_name).

Values: 温故知新 / 基礎と型

Step 7 — Register DI and Test End-to-End

Use when wiring Oracle services into DI and verifying the complete integration.

Add Oracle services to the existing DI setup from dotnet-wpf-secure-config.

// App.xaml.cs — Add to existing OnStartup
protected override void OnStartup(StartupEventArgs e)
{
    base.OnStartup(e);
    var services = new ServiceCollection();
    // ✅ From dotnet-wpf-secure-config (already registered)
    services.AddSingleton<ISecureConfigService, SecureConfigService>();
    // 🆕 Oracle integration (Transient: fresh connection per operation)
    services.AddTransient<ISofRepository, SofDatabaseOracle>();
    services.AddTransient<OracleConfigViewModel>();
    _serviceProvider = services.BuildServiceProvider();
}

// Launch settings dialog
var vm = _serviceProvider.GetRequiredService<OracleConfigViewModel>();
new OracleConfigDialog(vm).ShowDialog();

// Smoke test: connection + parameterized query
var repo = _serviceProvider.GetRequiredService<ISofRepository>();
var sysdate = await repo.QueryAsync("SELECT SYSDATE FROM DUAL");
Debug.Assert(sysdate.Count == 1, "SYSDATE query should return 1 row");

Test sequence: Settings dialog (save/reload/decrypt) → Connection test (SELECT SYSDATE FROM DUAL) → Query with SQL from dotnet-access-to-oracle-migration → Error handling (wrong credentials → ORA-01017).

Values: 成長の複利 / 継続は力

Common Pitfalls

1. Using TNS Names with Oracle.ManagedDataAccess.Core

Problem: Data Source=PROD_DSN fails with ORA-50201 because the NuGet package cannot resolve ODBC DSN or TNS names. Solution: Run tnsping PROD_DSN to get EZ Connect format, then use Data Source=192.0.2.10:1521/prod_service.

2. Connection Pool Leaks

Problem: Forgetting using / Dispose() on OracleConnection exhausts the connection pool. Solution: Always use await using var conn = ... to ensure connections return to the pool.

// ❌ WRONG — Connection leaks if exception occurs
var conn = new OracleConnection(connStr);
conn.Open();

// ✅ CORRECT — Connection always returned to pool
await using var conn = new OracleConnection(connStr);
await conn.OpenAsync();

3. Oracle Double-Quote Escaping in C#

Problem: C# verbatim strings require doubling ", making Oracle quoted identifiers hard to read. Solution: Use @"" syntax consistently and comment the intended Oracle SQL.

// Oracle SQL: SELECT s."ship_date" FROM SCHEMA_A."production_info" s
string sql = @"SELECT s.""ship_date"" FROM SCHEMA_A.""production_info"" s";

4. Hardcoding Connection Strings

Problem: Embedding User Id=SCOTT;Password=tiger directly in C# code. Solution: Always read from ISecureConfigService and build connection strings at runtime.

Anti-Patterns

SQL in ViewModel

What: Writing Oracle queries directly in the ViewModel or code-behind. Why It's Wrong: Mixes presentation concerns with data access; untestable without a database. Better Approach: All SQL goes through ISofRepository in the Infrastructure layer.

Ignoring Parameterized Queries

What: String-concatenating user input into SQL queries. Why It's Wrong: SQL injection vulnerability. Better Approach: Always use OracleParameter for dynamic values.

// ❌ WRONG — SQL injection risk
cmd.CommandText = $"SELECT * FROM users WHERE name = '{userInput}'";
// ✅ CORRECT — Parameterized query
cmd.CommandText = "SELECT * FROM users WHERE name = :name";
cmd.Parameters.Add(new OracleParameter(":name", userInput));

Skipping DPAPI for Oracle Passwords

What: Storing Oracle passwords in plaintext config files or environment variables. Why It's Wrong: Anyone with file system access can read the password. Better Approach: Use OracleConfigModel.SetPassword() which encrypts via DpapiEncryptor.

Quick Reference

ORA-* Error Code Quick Reference

TNS vs EZ Connect Decision

Implementation Checklist

• Install NuGet: Oracle.ManagedDataAccess.Core, CommunityToolkit.Mvvm
• Create OracleConfigModel.cs and update AppConfigModel (Step 2)
• Add Oracle methods to ISecureConfigService and SecureConfigService (Step 2)
• Create OracleConfigViewModel.cs with connection test (Step 3)
• Create OracleConfigDialog.xaml + .xaml.cs (Step 3)
• Create ISofRepository + SofDatabaseOracle (Step 4)
• Add ORA-* error handling (Step 6)
• Register services and test end-to-end (Step 7)
• Replace all YourApp namespace placeholders

Resources

• dotnet-access-to-oracle-migration — SQL conversion workflow for preparing Oracle queries
• Oracle.ManagedDataAccess.Core NuGet