> For the complete documentation index, see [llms.txt](https://docs.flexbase.in/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.flexbase.in/solution-structure/getting-started/features/rest-services/delete-example.md).

# Delete Example

## Overview

This document demonstrates the complete **Delete flow** using the **DeleteShipping** feature from the EBusiness application. The flow starts with a DELETE request to the controller and ends with event publishing and subscriber processing.

## Complete Flow Architecture

```
DELETE Request → Controller → Service → PreBus Plugins → Command Handler → RESTClient → External System
                                                                                    ↓
Response ← Controller ← Service ← Command Handler ← RESTClient ← External System
```

### **Detailed Flow Breakdown**

```
1. DELETE Request
   ↓
2. Controller (API Entry Point)
   ↓
3. Service Layer (Business Orchestration)
   ↓
4. PreBus Processing (Validation Pipeline)
   ├── DeleteShippingSequence (Plugin Registration)
   ├── DeleteShippingDataPacket (Validation Context)
   └── IsValidShipping Plugin (Business Rules)
   ↓
5. Command Handler (RESTClient Integration)
   ├── Internal DTO → Request DTO Mapping
   ├── RESTClient Call to External System
   └── Response DTO Processing
   ↓
6. Event Publishing (Asynchronous Processing)
   ↓
7. Subscribers (Side Effects)
```

## Step-by-Step Implementation

### 1. **API Controller** - The Entry Point

**File**: `ShippingController_DeleteShipping.cs`

```csharp
[HttpDelete()]
[Route("DeleteShipping/{id}")]
public async Task<IActionResult> DeleteShipping(string id)
{
    DeleteShippingDto dto = new DeleteShippingDto();
    dto.Id = id;
    return await RunService(200, dto, _processShippingService.DeleteShipping);
}
```

**What Happens:**

* **HTTP Method**: `DELETE /api/Shipping/DeleteShipping/{id}`
* **Input**: Shipping ID from URL parameter
* **DTO Creation**: Creates `DeleteShippingDto` with the ID
* **Action**: Calls the service layer to process the shipping deletion
* **Response**: HTTP 200 OK with success status

### 2. **Service Layer** - Business Orchestration

**File**: `ProcessShippingService_DeleteShipping.cs`

```csharp
public async Task<CommandResult> DeleteShipping(DeleteShippingDto dto)
{
    var packet = await ProcessBusinessRuleSequence<DeleteShippingDataPacket, DeleteShippingSequence, DeleteShippingDto, FlexAppContextBridge>(dto);

    if (packet.HasError)
    {
        return new CommandResult(Status.Failed, packet.Errors());
    }
    else
    {
        dto.SetGeneratedId(_pkGenerator.GenerateKey());
        DeleteShippingCommand cmd = new DeleteShippingCommand
        {
            Dto = dto,
        };

        await ProcessCommand(cmd);

        CommandResult cmdResult = new CommandResult(Status.Success);

        DeleteShippingResultModel outputResult = new DeleteShippingResultModel();
        cmdResult.result = outputResult;
        return cmdResult;
    }
}
```

**What Happens:**

* **PreBus Processing**: Executes business rule sequences (plugins)
* **Validation**: Processes business rule sequences
* **ID Generation**: Generates unique key for tracking
* **Command Creation**: Creates `DeleteShippingCommand` with DTO
* **Command Processing**: Calls the command handler
* **Result**: Returns success status

### 2.1. **PreBus Business Rule Sequence** - Validation Pipeline

**File**: `DeleteShippingSequence.cs`

```csharp
public class DeleteShippingSequence : FlexiBusinessRuleSequenceBase<DeleteShippingDataPacket>
{
    public DeleteShippingSequence()
    {
        this.Add<IsValidShipping>(); 
    }
}
```

**What Happens:**

* **Plugin Registration**: Registers validation plugins in execution order
* **Sequential Processing**: Executes plugins one by one
* **Error Collection**: Collects validation errors from all plugins
* **Early Exit**: Stops processing if any plugin fails

### 2.2. **PreBus Data Packet** - Validation Context

**File**: `DeleteShippingDataPacket.cs`

```csharp
public partial class DeleteShippingDataPacket : FlexiFlowDataPacketWithDtoBridge<DeleteShippingDto, FlexAppContextBridge>
{
    protected readonly ILogger<DeleteShippingDataPacket> _logger;

    public DeleteShippingDataPacket(ILogger<DeleteShippingDataPacket> logger)
    {
        _logger = logger;
    }

    #region "Properties
    //Models and other properties goes here
    #endregion
}
```

**What Happens:**

* **Context Container**: Holds DTO and application context
* **Error Collection**: Collects validation errors from plugins
* **Data Sharing**: Allows plugins to share data during validation
* **Logging**: Provides logging capabilities for plugins

### 2.3. **PreBus Validation Plugin** - Business Rules

**File**: `IsValidShipping.cs`

```csharp
public partial class IsValidShipping : FlexiBusinessRuleBase, IFlexiBusinessRule<DeleteShippingDataPacket>
{
    public override string Id { get; set; } = "3a1cd5b1fa98b4c63378de9607706082";
    public override string FriendlyName { get; set; } = "IsValidShipping";

    protected readonly ILogger<IsValidShipping> _logger;
    protected readonly RepoFactory _repoFactory;

    public IsValidShipping(ILogger<IsValidShipping> logger, RepoFactory repoFactory)
    {
        _logger = logger;
        _repoFactory = repoFactory;
    }

    public virtual async Task Validate(DeleteShippingDataPacket packet)
    {
        //Uncomment the below line if validating against a db data using your repo
        //_repoFactory.Init(packet.Dto);

        //If any validation fails, uncomment and use the below line of code to add error to the packet
        //packet.AddError("key", "ErrorMessage");

        await Task.CompletedTask; //If you have any await in the validation, remove this line
    }
}
```

**What Happens:**

* **Business Rule Validation**: Implements specific validation logic
* **Database Access**: Can access repository for data validation
* **Error Reporting**: Adds errors to the data packet if validation fails
* **Async Support**: Supports asynchronous validation operations
* **Dependency Injection**: Receives logger and repository factory

### 3. **Command Handler** - RESTClient Integration

**File**: `DeleteShippingHandler.cs`

```csharp
public partial class DeleteShippingHandler : IDeleteShippingHandler
{
    protected string EventCondition = "";
    protected readonly ILogger<DeleteShippingHandler> _logger;
    protected readonly IFlexHost _flexHost;
    protected ShippingRESTClient _restClient;
    protected FlexAppContextBridge? _flexAppContext;

    public DeleteShippingHandler(ILogger<DeleteShippingHandler> logger, IFlexHost flexHost, ShippingRESTClient restClient)
    {
        _logger = logger;
        _flexHost = flexHost;
        _restClient = restClient;
    }

    public virtual async Task Execute(DeleteShippingCommand cmd, IFlexServiceBusContext serviceBusContext)
    {
        // Convert internal DTO to Request DTO
        DeleteShippingRequestDto requestParams = new DeleteShippingRequestDto
        {
            Id = cmd.Dto.Id,
            DeletionReason = cmd.Dto.DeletionReason ?? "User requested deletion"
        };

        // Call external REST service
        var response = await _restClient.DeleteShipping(requestParams);

        // Process response
        if (response.IsSuccessStatusCode)
        {
            var responseContent = await response.Content.ReadAsStringAsync();
            var responseDto = JsonConvert.DeserializeObject<DeleteShippingResponseDto>(responseContent);
            
            _logger.LogDebug("Shipping deleted successfully with external ID: {ExternalId}", responseDto?.Id);
            
            // Set success condition for event firing
            EventCondition = "CONDITION_ONSUCCESS";
        }
        else
        {
            _logger.LogError("Failed to delete shipping. Status: {StatusCode}", response.StatusCode);
            EventCondition = "CONDITION_ONFAILED";
        }

        await this.Fire(EventCondition, serviceBusContext);
    }
}
```

**What Happens:**

* **DTO Mapping**: Converts internal DTO to Request DTO for external system
* **RESTClient Call**: Calls external shipping service via RESTClient
* **Response Processing**: Handles success/failure responses from external system
* **Logging**: Logs success/failure of external service call
* **Event Publishing**: Fires events based on external service result

### 4. **Domain Model** - Business Logic

**File**: `Shipping/DeleteShipping.cs`

```csharp
public virtual Shipping DeleteShipping(DeleteShippingCommand cmd)
{
    Guard.AgainstNull("Shipping model cannot be empty", cmd);

    this.Id = cmd.Dto.Id;
    this.SetDeleted();

    //Set your appropriate SetDeleted for the inner object here

    return this;
}
```

**What Happens:**

* **Validation**: Guards against null commands
* **ID Assignment**: Sets the shipping ID from DTO
* **State Management**: Marks entity as deleted (soft delete)
* **Child Objects**: Processes child object deletions

### 5. **NServiceBus Handler** - Message Processing

**File**: `DeleteShippingNsbHandler.cs`

```csharp
public class DeleteShippingNsbHandler : NsbCommandHandler<DeleteShippingCommand>
{
    readonly ILogger<DeleteShippingNsbHandler> _logger;
    readonly IFlexHost _flexHost;
    readonly IDeleteShippingHandler _handler;

    public DeleteShippingNsbHandler(ILogger<DeleteShippingNsbHandler> logger, IFlexHost flexHost, IDeleteShippingHandler handler)
    {
        _logger = logger;
        _flexHost = flexHost;
        _handler = handler;
    }

    public override async Task Handle(DeleteShippingCommand message, IMessageHandlerContext context)
    {
        _logger.LogTrace($"Executing {nameof(DeleteShippingNsbHandler)}");

        await _handler.Execute(message, new NsbHandlerContextBridge(context));
    }
}
```

**What Happens:**

* **Message Reception**: Receives `DeleteShippingCommand` from message bus
* **Logging**: Logs handler execution
* **Delegation**: Calls the actual command handler
* **Context Bridge**: Converts NServiceBus context to FlexBase context

### 6. **Event Publishing** - Asynchronous Processing

**Event**: `ShippingDeletedEvent` (if implemented)

```csharp
public class ShippingDeletedEvent : FlexEventBridge<FlexAppContextBridge>
{
    // Event data is automatically populated by FlexBase
}
```

**What Happens:**

* **Event Creation**: FlexBase creates event with shipping data
* **Message Bus**: Event is published to message bus
* **Subscriber Notification**: All subscribers are notified

### 7. **Event Subscribers** - Side Effects

**File**: `NotifyLogisticsOnShippingDeleted.cs` (if implemented)

```csharp
public partial class NotifyLogisticsOnShippingDeleted : INotifyLogisticsOnShippingDeleted
{
    protected readonly ILogger<NotifyLogisticsOnShippingDeleted> _logger;
    protected string EventCondition = "";

    public NotifyLogisticsOnShippingDeleted(ILogger<NotifyLogisticsOnShippingDeleted> logger)
    {
        _logger = logger;
    }

    public virtual async Task Execute(ShippingDeletedEvent @event, IFlexServiceBusContext serviceBusContext)
    {
        _flexAppContext = @event.AppContext;

        //TODO: Write your business logic here:
        // - Update logistics systems
        // - Notify carriers
        // - Update analytics
        // - Archive related data

        await this.Fire<NotifyLogisticsOnShippingDeleted>(EventCondition, serviceBusContext);
    }
}
```

**What Happens:**

* **Event Reception**: Receives `ShippingDeletedEvent` from message bus
* **Side Effects**: Executes business logic (logistics updates, notifications, etc.)
* **Additional Events**: Can fire more events if needed

## Data Transfer Objects (DTOs)

### **Input DTO**: `DeleteShippingDto`

```csharp
public partial class DeleteShippingDto : DtoBridge 
{
    public string Id { get; set; }
}
```

### **Command**: `DeleteShippingCommand`

```csharp
public class DeleteShippingCommand : FlexCommandBridge<DeleteShippingDto, FlexAppContextBridge>
{
    // Command data is automatically populated by FlexBase
}
```

## Key Differences from Insert/Update Flow

### **Delete-Specific Characteristics**

1. **URL Parameter**: ID comes from URL path instead of request body
2. **DTO Creation**: Controller creates DTO with ID from URL
3. **Soft Delete**: Uses `SetDeleted()` instead of `SetAdded()` or `SetModified()`
4. **State Management**: Marks entity as deleted (soft delete pattern)
5. **HTTP Method**: Uses `DELETE` instead of `POST` or `PUT`
6. **Minimal Data**: Only requires ID for deletion

### **PreBus Validation Focus**

* **IsValidShipping**: Validates shipping exists and can be deleted
* **Business Rules**: Ensures shipping can be removed (not delivered, not in transit)
* **Data Integrity**: Validates deletion doesn't violate business constraints

### **Soft Delete Pattern**

* **Database**: Entity is marked as deleted, not physically removed
* **Queries**: Soft-deleted entities are filtered out of normal queries
* **Recovery**: Deleted entities can be restored if needed
* **Audit Trail**: Maintains complete history of deletions

## Flow Summary

### **Synchronous Flow (Immediate Response)**

1. **DELETE Request** → Controller receives request with ID
2. **Service Processing** → Business orchestration and PreBus validation
3. **PreBus Plugins** → Sequential validation of business rules
4. **Command Handler** → Data processing and soft delete
5. **Domain Logic** → Business rules and state management
6. **Response** → HTTP 200 OK with success status

### **Asynchronous Flow (Event Processing)**

1. **Event Publishing** → ShippingDeletedEvent published to message bus
2. **Subscriber Processing** → NotifyLogisticsOnShippingDeleted executes
3. **Side Effects** → Logistics updates, carrier notifications, analytics

## Key Benefits

* **Data Safety**: Soft delete preserves data for recovery
* **Business Rules**: Validates deletion is allowed
* **Audit Trail**: Tracks who deleted what and when
* **Event-Driven**: Notifies other systems of deletions
* **Testable**: Each component can be tested independently
* **Maintainable**: Clear separation of concerns

***

**This DeleteShipping example demonstrates how FlexBase enables clean, maintainable, and scalable delete operations with proper validation, soft delete patterns, and event-driven architecture!** 🚀