# SQLx Askama Template
[](https://crates.io/crates/sqlx-askama-template)
[](https://docs.rs/sqlx-askama-template)
[](https://github.com/gouhengheng/sqlx-askama-template)
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[](https://github.com/gouhengheng/sqlx-askama-template/issues)
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A SQLx query builder based on the Askama template engine, providing type-safe SQL templates and parameter binding.
## Features
- 🚀 **Zero-Cost Abstraction** - Compile-time optimized SQL generation
- 🔒 **Type Safety** - Automatic validation of SQL parameter types
- 📦 **Multi-Database Support** - PostgreSQL/MySQL/SQLite/Any
- 💡 **Smart Parameter Binding** - Auto-expansion for list parameters
- 🎨 **Template Syntax** - Full Askama templating capabilities
## Installation
Add to `Cargo.toml`:
```toml
[dependencies]
sqlx-askama-template = "0.3.1"
sqlx = { version = "0.8", features = ["all-databases", "runtime-tokio"] }
tokio = { version = "1.0", features = ["full"] }
```
## Quick Start
### Basic Usage
```rust
use sqlx::{AnyPool, Error, any::install_default_drivers};
use sqlx_askama_template::{BackendDB, DBType, SqlTemplate};
#[derive(sqlx::prelude::FromRow, PartialEq, Eq, Debug)]
struct User {
id: i64,
name: String,
}
#[derive(SqlTemplate)]
#[template(source = r#"
select {{e(user_id)}} as id,{{e(user_name)}} as name
union all
{%- let id=99999_i64 %}
{%- let name="super man" %}
select {{et(id)}} as id,{{et(name)}} as name
"#)]
#[add_type(&'q str)]
pub struct UserQuery {
pub user_id: i64,
pub user_name: String,
}
async fn simple_query(urls: Vec<(DBType, &str)>) -> Result<(), Error> {
let users = [
User {
id: 1,
name: "admin".to_string(),
},
User {
id: 99999_i64,
name: "super man".to_string(),
},
];
let user_query = UserQuery {
user_id: 1,
user_name: "admin".to_string(),
};
for (db_type, url) in urls {
let pool = AnyPool::connect(url).await?;
// pool
let user: Option<User> = user_query
.adapter_render()
.set_page(1, 1)
.fetch_optional_as(&pool)
.await?;
assert_eq!(user.as_ref(), users.first());
// connection
let mut conn = pool.acquire().await?;
let users1: Vec<User> = user_query
.adapter_render()
.set_page(1, 2)
.fetch_all_as(&mut *conn)
.await?;
assert_eq!(users1, users[1..]);
// tx
let mut conn = pool.begin().await?;
let (get_db_type, _get_conn) = conn.backend_db().await?;
assert_eq!(db_type, get_db_type);
let page_info = user_query
.adapter_render()
.count_page(1, &mut *conn)
.await?;
assert_eq!(page_info.total, 2);
assert_eq!(page_info.page_count, 2);
}
Ok(())
}
#[tokio::main]
async fn main() -> Result<(), Error> {
unsafe {
std::env::set_var("RUST_LOG", "sqlx_askama_template=DEBUG");
}
env_logger::init();
install_default_drivers();
let urls = vec![
(
DBType::PostgreSQL,
"postgres://postgres:postgres@localhost/postgres",
),
(DBType::SQLite, "sqlite://db.file?mode=memory"),
// (DBType::MySQL, "mysql://root:root@localhost/mysql"),
];
simple_query(urls).await?;
Ok(())
}
```
## Core Features
### Template Syntax
| Single Parameter | `{{e(user_id)}}` | Binds a single parameter |
| List Expansion | `{{el(ids)}}` | Expands to `IN (?, ?)` |
| Temporary Variables | `{% let limit = 100 %}` | Defines template-local variables |
| Conditional Logic | `{% if active %}...{% endif %}` | Dynamic SQL conditions |
### Parameter Encoding Methods
| `e()` | Encodes a single value | `{{e(user_id)}}` |
| `el()` | Encodes a list (`$1, $2...`) | `{{el(ids)}}` |
| `et()` | Encodes a template-local value | `{{et(limit)}}` |
| `etl()` | Encodes a template-local list | `{{etl(filters)}}` |
## Multi-Database Support
| PostgreSQL | `$1, $2` | `WHERE id = $1` |
| MySQL | `?` | `WHERE id = ?` |
| SQLite | `?` | `WHERE id = ?` |
## Macro Attributes
### `#[template]` - Core Template Attribute
```rust
#[derive(SqlTemplate)]
#[template(
source = "SQL template content", // Required
ext = "txt", // Askama file extension
print = "all", // Optional debug output (none, ast, code, all)
config = "path" // Optional custom Askama config path
)]
```
**Parameters**:
- `source`: Inline SQL template content (supports Askama syntax)
- `ext`: Askama file extension
- `print`: Debug mode for Askama
- `config`: Path to a custom Askama configuration file
### `#[add_type]` - Add Additional Type Constraints
Used to add `Encode + Type` constraints for non-field types in templates (e.g., `Vec<T>`, `HashMap<K, V>`).
```rust
#[derive(SqlTemplate)]
#[add_type(chrono::NaiveDate, Option<&'a str>)] // Add extra type support
```
**Features**:
- Adds type constraints for template-local variables
- Supports comma-separated types
### `#[ignore_type]` - Skip Field Type Constraints
```rust
#[derive(SqlTemplate)]
struct Query {
#[ignore_type] // Skip type checks for this field
metadata: JsonValue
}
```
**Use Cases**:
- Skip fields that do not require SQLx parameter binding
- Avoid unnecessary trait constraints for complex types
## Full Example
```rust
use std::collections::HashMap;
use sqlx_askama_template::SqlTemplate;
#[derive(SqlTemplate)]
#[template(
source = r#"
{% let status_list = ["active", "pending"] %}
SELECT
u.id,
u.name,
COUNT(o.id) AS order_count
FROM users u
LEFT JOIN orders o ON u.id = o.user_id
WHERE 1=1
{% if let Some(min_age) = min_age %}
AND age >= {{et(min_age)}}
{% endif %}
{% if filter_names.len()>0 %}
AND name IN {{el(filter_names)}}
{% endif %}
AND status IN {{etl(*status_list)}}
GROUP BY u.id
ORDER BY {{order_field}}
LIMIT {{e(limit)}}
"#,
ext = "txt"
)]
#[add_type(i32)]
pub struct ComplexQuery<'a> {
min_age: Option<i32>,
#[ignore_type]
filter_names: Vec<&'a str>,
order_field: &'a str,
limit: i64,
}
#[test]
fn render_complex_sql() {
let data = ComplexQuery {
filter_names: vec!["name1", "name2"],
limit: 10,
min_age: Some(18),
order_field: "id",
};
let (sql, arg) =
<&ComplexQuery<'_> as SqlTemplate<'_, sqlx::Postgres>>::render_sql(&data).unwrap();
use sqlx::Arguments;
assert_eq!(arg.unwrap().len(), 6);
println!("----{sql}----");
}
#[derive(SqlTemplate)]
#[add_type(Option<&'a i64>, bool)]
#[template(
ext = "txt",
source = r#"
{% let v="abc".to_string() %}
SELECT {{et(v)}} as v,t.* FROM table t
WHERE arg1 = {{e(arg1)}}
AND arg2 = {{e(arg2)}}
AND arg3 = {{e(arg3)}}
AND arg4 = {{e(arg4.first())}}
AND arg5 = {{e(arg5.get(&0))}}
{% let v2=3_i64 %}
AND arg6 = {{et(v2)}}
{% let v3="abc".to_string() %}
AND arg7 = {{et(v3)}}
AND arg_list1 in {{el(arg4)}}
{% let list=["abc".to_string()] %}
AND arg_temp_list1 in {{etl(*list)}}
AND arg_list2 in {{el(arg5.values())}}
{% if let Some(first) = arg4.first() %}
AND arg_option = {{et(**first)}}
{% endif %}
{% if let Some(first) = arg5.get(&0) %}
AND arg_option1 = {{et(**first)}}
{% endif %}
"#,
print = "all"
)]
pub struct QueryData<'a, T>
where
T: Sized,
{
arg1: i64,
_arg1: i64, // Same type
arg2: String,
arg3: &'a str,
#[ignore_type]
arg4: Vec<i64>,
#[ignore_type]
arg5: HashMap<i32, i64>,
#[ignore_type]
#[allow(unused)]
arg6: T,
}
#[test]
fn render_query_data_sql() {
let data = QueryData {
arg1: 42,
_arg1: 123,
arg2: "value".to_string(),
arg3: "reference",
arg4: vec![12, 12, 55, 66],
arg5: HashMap::from_iter([(0, 2), (1, 2), (2, 3)]),
arg6: 1,
};
let (sql, arg) =
<&QueryData<'_, i32> as SqlTemplate<'_, sqlx::Postgres>>::render_sql(&data).unwrap();
use sqlx::Arguments;
assert_eq!(arg.unwrap().len(), 18);
println!("----{sql}----");
}
```
## Best Practices
```markdown
1. Use `{% if %}` blocks for dynamic SQL
2. Use `add_type` to add type constraints for template-local variables
3. Use `ignore_type` to skip serialization for specific fields
4. Set `print = "none"` in production
```
## License
This project is licensed under the [Apache License 2.0](LICENSE).
Copyright © 2025 gouhengheng
> **Important Notice**:
> Under the Apache 2.0 License, you may not use this file except in compliance with the License.
> You may obtain a copy of the License at:
> <http://www.apache.org/licenses/LICENSE-2.0>
>
> Unless required by applicable law or agreed to in writing, software
> distributed under the License is distributed on an "AS IS" BASIS,
> WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
> See the License for specific governing permissions and limitations.