Crate include_sqlite_sql
source ·Expand description
include-sqlite-sql is an extension of include-sql for using SQLite SQL in Rust. It completes include-sql by providing impl_sql
macro to generate database access methods from the included SQL. include-sqlite-sql uses Rusqlite for database access.
Usage
Add include-sqlite-sql
as a dependency:
[dependencies]
include-sqlite-sql = "0.2"
Write your SQL and save it in a file. For example, let’s say the following is the content of the library.sql
file that is saved in the project’s src
folder:
-- name: get_loaned_books?
-- Returns the list of books loaned to a patron
-- # Parameters
-- param: user_id: &str - user ID
SELECT book_title
FROM library
WHERE loaned_to = :user_id
ORDER BY 1
/
-- name: loan_books!
-- Updates the book records to reflect loan to a patron
-- # Parameters
-- param: book_titles: &str - book titles
-- param: user_id: &str - user ID
UPDATE library
SET loaned_to = :user_id
, loaned_on = current_timestamp
WHERE book_title IN (:book_titles)
/
And then use it in Rust as:
use include_sqlite_sql::{include_sql, impl_sql};
use rusqlite::{Result, Connection};
include_sql!("src/library.sql");
fn main() -> Result<()> {
let db = Connection::open("library.db")?;
db.loan_books(&["War and Peace", "Gone With the Wind"], "Sheldon Cooper")?;
db.get_loaned_books("Sheldon Cooper", |row| {
let book_title : &str = row.get_ref("book_title")?.as_str()?;
println!("{book_title}");
Ok(())
})?;
Ok(())
}
Note that the path to the SQL file must be specified relative to the project root, i.e. relative to
CARGO_MANIFEST_DIR
, even if you keep your SQL file alongside rust module that includes it. Because include-sql targets stable Rust this requirement will persist until SourceFile stabilizes.
Anatomy of the Included SQL File
Please see the Anatomy of the Included SQL File in include-sql documentation for the description of the format that include-sql can parse.
Generated Methods
include-sqlite-sql generates 3 variants of database access methods using the following selectors:
?
- methods that process rows retrieved bySELECT
,!
- methods that execute all other non-SELECT
methods, and&
- methods that execute multiple SQL statements (as a batch), and->
- methods that executeRETURNING
statements and provide access to returned data.
Process Selected Rows
For the SELECT
statement like:
-- name: get_loaned_books?
-- param: user_id: &str
SELECT book_title FROM library WHERE loaned_to = :user_id;
The method with the following signature is generated:
fn get_loaned_books<F>(&self, user_id: &str, row_callback: F) -> rusqlite::Result<()>
where F: Fn(&rusqlite::Row) -> rusqlite::Result<()>;
Where:
user_id
is a parameter that has the same name as the SQL parameter with the declared (in the SQL) type as&str
.F
is a type of a callback (closure) that the method implementation will call to process each row.
Execute Non-Select Statements
For non-select statements - INSERT, UPDATE, DELETE, etc. - like the following:
-- name: loan_books!
-- param: user_id: &str
-- param: book_ids: u32
UPDATE library
SET loaned_to = :user_id
, loaned_on = current_timestamp
WHERE book_id IN (:book_ids);
The method with the following signature is generated:
fn loan_books(&self, user_id: &str, book_ids: &[u32]) -> rusqlite::Result<usize>;
Where:
user_id
is a parameter that has the same name as the SQL parameter with the declared (in the SQL) type as&str
,book_ids
is a parameter for the matching IN-list parameter where each item in a collection has typeu32
.
RETURNING Statements
For DELETE, INSERT, and UPDATE statements that return data via RETURNING
clause like:
-- name: add_new_book->
-- param: isbn: &str
-- param: book_title: &str
INSERT INTO library (isbn, book_title)
VALUES (:isbn, :book_title)
RETURNING book_id;
The method with the following signature is generated:
fn add_new_book<F,R>(&self, isbn: &str, book_title: &str, row_callback: F) -> rusqlite::Result<R>
where F: FnOnce(&rusqlite::Row) -> rusqlite::Result<R>;
Inferred Parameter Types
If a statement parameter type is not explicitly specified via param:
, include-sqlite-sql will use impl rusqlite::ToSql
for the corresponding scalar method parameters. For example, if the SQL from the example above has not provided its parameter type:
-- name: get_loaned_books?
SELECT book_title
FROM library
WHERE loaned_to = :user_id
ORDER BY 1;
Then the signature of the generated method would be:
fn get_loaned_books<F>(&self, user_id: impl rusqlite::ToSql, row_callback: F) -> rusqlite::Result<()>
where F: Fn(&rusqlite::Row) -> rusqlite::Result<()>;
For the “IN list” type of parameters include-sqlite-sql will generate a method parameter as a slice where each element is the same generic type supplied by include-sql:
-- name: loan_books!
UPDATE library
SET loaned_to = :user_id
, loaned_on = current_timestamp
WHERE book_id IN (:book_ids);
The signature of the generated method would be:
fn loan_books<BookIds: rusqlite::ToSql>(&self, user_id: impl rusqlite::ToSql, book_ids: &[BookIds]) -> rusqlite::Result<usize>;
Macros
- Generates Rust code to use included SQL.
- Reads and parses the specified SQL file, and generates
impl_sql
macro call. - Finds the specified item (
ident
) in a list (ofidents
).