2 releases
0.0.1-beta | Sep 2, 2024 |
---|---|
0.0.1-alpha | Aug 25, 2024 |
#614 in Rust patterns
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14KB
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sqler - beta
A procedural macro that helps with writing SQL queries using some of Rust syntax
Usage
First, in your Cargo.toml file add the following:
[dependencies]
sqler = "0.0.1-beta"
Example 1
To just embedding a value of a varible you can just do the following:
use sqler::sql;
fn main() {
let first_name = String::from("Ali");
let age = 24;
let query = sql!(
SELECT * FROM users
WHERE first_name = {first_name}
OR age = {age}
);
assert_eq!(
query,
"SELECT * FROM users WHERE first_name='Ali' OR age=24"
);
}
This macro will handle the process of embedding value of any variable (only built-in types) in addition to converting the Rust syntax to string that contains SQL statement.
Example 2
Also you can write the value directly:
use sqler::sql;
fn main() {
let query = sql!(
SELECT * FROM users
WHERE first_name = "Ali"
OR age = 24
);
assert_eq!(
query,
"SELECT * FROM users WHERE first_name='Ali' OR age=24"
);
}
Example 3
You can also use hexadecimal, octal, or binary number format and the macro will handle it by converting the value back to decimal.
use sqler::sql;
fn main() {
let query = sql!(
UPDATE employees
SET
age=0x1f,
salery=0o5776
WHERE
emp_id=0b101
);
assert_eq!(
query,
"UPDATE employees SET age=31,salery=3070 WHERE emp_id=5"
);
}
Example 4
What about variable of a custom type? variable of a custom type can be embedded by first implementing the "VarToSql" trait (which tells the macro how to embed the value of that type) as follows:
use sqler::{sql, VarToSql};
struct IntArr(Vec<i32>);
impl VarToSql for IntArr {
#[inline]
fn sql(&self) -> String {
let mut sql = String::from("ARRAY[");
for i in 0..self.0.len() - 1 {
sql.push_str(&self.0[i].to_string());
sql.push_str(", ");
}
sql.push_str(&self.0[self.0.len() - 1].to_string());
sql.push_str("]::INT[]");
sql
}
}
fn main() {
let permissions = IntArr(vec![1, 2, 3]);
let query = sql!(
INSERT INTO user_permissions
(user_id, permissions)
VALUES
(1, {permissions})
);
assert_eq!(
query,
"INSERT INTO user_permissions(user_id,permissions) VALUES (1,ARRAY[1, 2, 3]::INT[])"
);
}
Notes
There are a few points you should consider when using this crate:
-
Delimited Identifier - or quoted identifier is not supported. For example:
SELECT "first_name"
the column namefirst_name
will be converted to a string (string is wrapped with single quote) as follows:SELECT 'first_name'
. -
Variables Of Custom Type - to use variables of a custom type the
VarToSql
trait should be implemented for this type.