Derive Macro DeleteTemplate 

#[derive(DeleteTemplate)]
{
    // Attributes available to this derive:
    #[table]
    #[tp_delete]
    #[tp_delete_builder]
    #[debug_slow]
    #[db]
    #[tp_delete_builder]
}

DeleteTemplate is a derive macro designed to automatically generate record deletion functions based on sqlx. This macro creates delete methods for the struct it is applied to, returning the number of records deleted. It assumes that the columns in the database correspond to the fields in the struct.

Attributes

DeleteTemplate accepts the following attributes:

• table: Specifies the name of the table in the database (mandatory).
• debug_slow: Configures debug logs for the executed query:
  • If set to 0: Only logs the executed query.
  • If set to a value greater than 0: Only logs the query if the execution time exceeds the configured value (in milliseconds).
  • If not configured, no debug logs will be generated.
• tp_delete: The main configuration for generating the delete function, with the following sub-attributes:
  • by: List of columns that will be the delete condition, will be the function’s input (can be empty if where is provided).
  • where: Additional WHERE clause with placeholder support (see Placeholder Mapping in SelectTemplate).
  • fn_name: The name of the generated function. If empty, the library will automatically generate a function name.
  • returning: Can be set to true for returning the full record, or specify specific columns (e.g., returning = "id, email").
  • debug_slow: Configures debug logs for the executed query:
    • If set to 0: Only logs the executed query.
    • If set to a value greater than 0: Only logs the query if the execution time exceeds the configured value (in milliseconds).
    • If not configured, no debug logs will be generated.
• db: Specifies the target database type (e.g., #[db("postgres")]).
• tp_delete_builder: Builder pattern configuration for DELETE operations with custom WHERE conditions.

Builder Pattern Support

The macro supports fluent builder patterns for query construction with custom WHERE conditions.

Builder Attributes

• tp_select_builder: Builder pattern configuration for SELECT operations
• tp_update_builder: Builder pattern configuration for UPDATE operations
• tp_delete_builder: Builder pattern configuration for DELETE operations

Custom Condition Syntax

Custom conditions are defined using the following syntax:

#[tp_select_builder(
    method_name = "SQL_expression_with_placeholders"
)]

Parameter Types

• Auto-mapping: :field_name automatically maps to struct field types
• Explicit types: :param$Type for custom parameter types
• Multiple parameters: Single condition can accept multiple parameters

Examples

#[tp_select_builder(
    with_email_domain = "email LIKE :domain$String",
    with_score_range = "score BETWEEN :min$i32 AND :max$i32",
    with_active_status = "active = :active"  // Auto-mapped to bool
)]

Generated Methods

For each field, the builder generates:

Field-based Methods

• Equality: .field_name(value), .field_name_not(value)
• Comparison: .field_name_gt(value), .field_name_gte(value), .field_name_lt(value), .field_name_lte(value)
• String operations: .field_name_like(pattern), .field_name_start_with(prefix), .field_name_end_with(suffix)
• Ordering: .order_by_field_asc(), .order_by_field_desc()

Builder-specific Methods

SELECT Builder

• Query execution: .find_all(), .find_one(), .count(), .find_page(), .stream()
• SQL generation: .build_sql()

UPDATE Builder

• SET clauses: .on_field_name(value) - specify which fields to update
• WHERE clauses: .by_field_name(value) - specify which records to update
• Execution: .execute() - returns number of affected rows

DELETE Builder

• WHERE clauses: .field_name(value) - specify which records to delete
• Execution: .execute() - returns number of deleted rows

Usage Examples

SELECT Builder

let users = User::builder_select()
    .email("john@example.com")?           // Field-based condition
    .score_gte(&75)?                      // Generated comparison method
    .with_email_domain("%@company.com")?  // Custom condition
    .with_score_range(60, 90)?            // Custom condition with multiple params
    .order_by_score_desc()?               // Generated ORDER BY method
    .find_all(&pool)
    .await?;

UPDATE Builder

let affected = User::builder_update()
    .on_email("newemail@example.com")?    // SET email = ?
    .on_active(&true)?                    // SET active = ?
    .by_id(&user_id)?                     // WHERE id = ?
    .with_high_score(80)?                 // Custom WHERE condition
    .execute(&pool)
    .await?;

DELETE Builder

let deleted = User::builder_delete()
    .active(&false)?                      // WHERE active = false
    .with_old_accounts("2023-01-01")?     // Custom WHERE condition
    .execute(&pool)
    .await?;

Validation

• Table alias validation: Prevents use of table aliases (e.g., u.field) in custom conditions
• Column validation: Ensures referenced columns exist in the struct
• Type safety: Compile-time parameter type checking
• SQL injection protection: Uses parameterized queries

Performance Features

• Compile-time optimization: SQL templates pre-generated at compile time
• Minimal runtime overhead: Reduced format! calls and string allocations
• Efficient parameter binding: Direct parameter binding without intermediate formatting

Document generated by LLMs

Example

use sqlx_template::DeleteTemplate;
use sqlx::Pool;

#[derive(DeleteTemplate, sqlx::FromRow)]
#[table("users")]
#[db("sqlite")]
#[tp_delete(by = "id", fn_name = "delete_user", returning = true)]
#[tp_delete(by = "id")]
#[tp_delete_builder(
    with_old_accounts = "created_at < :cutoff_date$String"
)]
pub struct User {
    pub id: i32,
    pub email: String,
    pub password: String,
    pub created_at: String,
}

let user = User {
    id: 1,
    email: "user@example.com".to_string(),
    password: "password".to_string(),
    created_at: "2024-01-01".to_string()
};

// Traditional delete:
let rows_affected = User::delete_by_id(&user.id, &pool).await?;

// Builder pattern delete:
let deleted = User::builder_delete()
    .with_old_accounts("2023-01-01")?
    .execute(&pool)
    .await?;

Note

This macro relies on sqlx, so you need to add sqlx to your [dependencies] in Cargo.toml and properly configure the database connection before using the generated delete methods.