# sqlx-record Soft Delete Skill

Guide to soft delete functionality with #[soft_delete] attribute.

## Triggers
- "soft delete", "soft-delete"
- "is_deleted", "deleted"
- "restore", "undelete"
- "hard delete", "permanent delete"

## Overview

Soft delete allows marking records as deleted without removing them from the database. This enables:
- Recovery of accidentally deleted data
- Audit trails of deletions
- Referential integrity preservation

## Enabling Soft Delete

Add `#[soft_delete]` to a boolean field:

```rust
use sqlx_record::prelude::*;

#[derive(Entity, FromRow)]
#[table_name = "users"]
struct User {
    #[primary_key]
    id: Uuid,
    name: String,

    #[soft_delete]
    is_deleted: bool,  // Must be bool type
}
```

Auto-detection: Fields named `is_deleted` or `deleted` with `bool` type are automatically treated as soft delete fields even without the attribute.

## Generated Methods

### delete() / delete_by_{pk}()
Sets the soft delete field to `true`:

```rust
// Instance method
user.delete(&pool).await?;

// Static method by primary key
User::delete_by_id(&pool, &user_id).await?;
```

**SQL generated:**
```sql
UPDATE users SET is_deleted = TRUE WHERE id = ?
```

### hard_delete() / hard_delete_by_{pk}()
Permanently removes the row:

```rust
// Instance method
user.hard_delete(&pool).await?;

// Static method by primary key
User::hard_delete_by_id(&pool, &user_id).await?;
```

**SQL generated:**
```sql
DELETE FROM users WHERE id = ?
```

### restore() / restore_by_{pk}()
Sets the soft delete field to `false`:

```rust
// Instance method
user.restore(&pool).await?;

// Static method by primary key
User::restore_by_id(&pool, &user_id).await?;
```

**SQL generated:**
```sql
UPDATE users SET is_deleted = FALSE WHERE id = ?
```

### soft_delete_field()
Returns the field name:

```rust
let field = User::soft_delete_field();  // "is_deleted"
```

## Filtering Deleted Records

Soft delete does **NOT** automatically filter `find()` queries. You must add the filter manually:

```rust
// Include only non-deleted
let users = User::find(&pool, filters![("is_deleted", false)], None).await?;

// Include only deleted (trash view)
let deleted = User::find(&pool, filters![("is_deleted", true)], None).await?;

// Include all records
let all = User::find(&pool, filters![], None).await?;
```

### Helper Pattern

Create a helper function for consistent filtering:

```rust
impl User {
    pub async fn find_active(
        pool: &Pool,
        mut filters: Vec<Filter<'_>>,
        index: Option<&str>
    ) -> Result<Vec<Self>, sqlx::Error> {
        filters.push(Filter::Equal("is_deleted", false.into()));
        Self::find(pool, filters, index).await
    }
}

// Usage
let users = User::find_active(&pool, filters![("role", "admin")], None).await?;
```

## Usage Examples

### Basic Soft Delete Flow

```rust
// Create user
let user = User {
    id: new_uuid(),
    name: "Alice".into(),
    is_deleted: false,
};
user.insert(&pool).await?;

// Soft delete
user.delete(&pool).await?;
// user still exists in DB with is_deleted = true

// Find won't return deleted users (with proper filter)
let users = User::find(&pool, filters![("is_deleted", false)], None).await?;
// Alice not in results

// Restore
User::restore_by_id(&pool, &user.id).await?;
// user.is_deleted = false again

// Hard delete (permanent)
User::hard_delete_by_id(&pool, &user.id).await?;
// Row completely removed from database
```

### With Audit Trail

```rust
use sqlx_record::{transaction, prelude::*};

async fn soft_delete_with_audit(
    pool: &Pool,
    user_id: &Uuid,
    actor_id: &Uuid
) -> Result<(), sqlx::Error> {
    transaction!(&pool, |tx| {
        // Soft delete the user
        User::delete_by_id(&mut *tx, user_id).await?;

        // Record the deletion
        let change = EntityChange {
            id: new_uuid(),
            entity_id: *user_id,
            action: "delete".into(),
            changed_at: chrono::Utc::now().timestamp_millis(),
            actor_id: *actor_id,
            session_id: Uuid::nil(),
            change_set_id: Uuid::nil(),
            new_value: None,
        };
        create_entity_change(&mut *tx, "entity_changes_users", &change).await?;

        Ok::<_, sqlx::Error>(())
    }).await
}
```

### Cascade Soft Delete

```rust
async fn delete_user_cascade(pool: &Pool, user_id: &Uuid) -> Result<(), sqlx::Error> {
    transaction!(&pool, |tx| {
        // Soft delete user's orders
        let orders = Order::find(&mut *tx, filters![("user_id", user_id)], None).await?;
        for order in orders {
            order.delete(&mut *tx).await?;
        }

        // Soft delete user
        User::delete_by_id(&mut *tx, user_id).await?;

        Ok::<_, sqlx::Error>(())
    }).await
}
```

## Database Schema

Recommended column definition:

```sql
-- MySQL
is_deleted BOOLEAN NOT NULL DEFAULT FALSE

-- PostgreSQL
is_deleted BOOLEAN NOT NULL DEFAULT FALSE

-- SQLite
is_deleted INTEGER NOT NULL DEFAULT 0  -- 0=false, 1=true
```

Add an index for efficient filtering:

```sql
CREATE INDEX idx_users_is_deleted ON users (is_deleted);

-- Or composite index for common queries
CREATE INDEX idx_users_active_name ON users (is_deleted, name);
```

## Notes

- Soft delete field must be `bool` type
- The field is included in UpdateForm (can be manually toggled)
- Consider adding `deleted_at: Option<i64>` for deletion timestamps
- For complex filtering, consider database views