include-postgres-sql is an extension of include-sql for using Postgres SQL in Rust. It completes include-sql by providing impl_sql macro to generate database access methods from the included SQL. include-postgres-sql uses Rust-Postgres for database access.

Usage

Include include-postgres-sql as a dependency:

toml [dependencies] include-postgres-sql = "0.1"

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:

```sql -- name: getloanedbooks? -- Returns the list of books loaned to a patron -- # Parameters -- param: userid: &str - user ID SELECT booktitle FROM library WHERE loanedto = :userid ORDER BY 1;

-- name: loanbooks! -- Updates the book records to reflect loan to a patron -- # Parameters -- param: userid: &str - user ID -- param: bookids: i32 - book IDs UPDATE library SET loanedto = :userid , loanedon = currenttimestamp WHERE bookid IN (:book_ids); ```

And then use it in Rust as:

```rust , ignore use includepostgressql::{includesql, implsql}; use postgres::{Config, NoTls, Error};

include_sql!("src/library.sql");

fn main() -> Result<(),Error> { let args : Vec = std::env::args().collect(); let user_id = &args[1];

let mut db = Config::new().host("localhost").connect(NoTls)?;

db.get_loaned_books(user_id, |row| {
    let book_title : &str = row.try_get("book_title")?;
    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-postgres-sql generates 3 variants of database access methods using the following selectors: * ? - methods that process rows retrieved by SELECT, * ! - methods that execute all other non-SELECT methods, and * -> - methods that execute RETURNING statements and provide access to returned data.

Process Selected Rows

For the SELECT statement like:

sql -- 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:

rust , ignore fn get_loaned_books<F>(&self, user_id: &str, row_callback: F) -> Result<(),postgres::Error> where F: Fn(postgres::Row) -> Result<(),postgres::Error>;

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:

sql -- name: loan_books! -- param: user_id: &str -- param: book_ids: i32 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:

rust , ignore fn loan_books(&self, user_id: &str, book_ids: &[i32]) -> Result<u64,postgres::Error>;

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 type u32.

RETURNING Statements

For DELETE, INSERT, and UPDATE statements that return data via RETURNING clause like:

sql -- 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:

rust , ignore fn add_new_book(&self, isbn: &str, book_title: &str) -> Result<postgres::Row,postgres::Error>;

Inferred Parameter Types

If a statement parameter type is not explicitly specified via param:, include-postgres-sql will use impl postgres::types::ToSql for the corresponding method parameters. For example, if the SQL from the example above has not provided its parameter type:

sql -- name: get_loaned_books? -- Returns the list of books loaned to a patron SELECT book_title FROM library WHERE loaned_to = :user_id ORDER BY 1;

Then the signature of the generated method would be:

rust , ignore /// Returns the list of books loaned to a patron fn get_loaned_books<F>(&self, user_id: impl postgres::types::ToSql, row_callback: F) -> Result<(),postgres::Error> where F: Fn(postgres::Row) -> Result<(),postgres::Error>;