Squiller

Squiller generates boilerplate code from annotated SQL queries.

Working with SQL is often tedious, especially in statically typed settings. You need to explicitly bind values to parameters, and extract the resulting values for every column with the right type. Squiller can generate this boilerplate code from a SQL file, based on annotations in comments.

Status

Squiller is a work in progress, beta quality at best. Basic code generation for the rust-sqlite target works, other targets are experimental and incomplete.

Example

Given the following input:

-- Look up a user by username.
-- @query get_user_by_name(name: str) ->? User
select
  id    /* :i64 */,
  name  /* :str */,
  email /* :str */
from
  users
where
  name = :name;

When targeting Rust and the sqlite crate, Squiller would generate roughly1:

struct User {
    id: i64,
    name: String,
    email: String,
}

/// Look up a user by username.
pub fn get_user_by_name(
    tx: &mut Transaction,
    name: &str
) -> Result<Option<User>> {
    let mut statement = tx.prepare(
        r#"
        select
          id,
          name,
          email
        from
          users
        where
          name = :name;
        "#
    )?;
    statement.bind(1, name)?;
    match statement.next()? {
        State::Done => Ok(None),
        State::Row => {
            let result = User {
                id: statement.read(0)?,
                name: statement.read(1)?,
                email: statement.read(2)?,
            };
            Ok(Some(result))
        }
    }
}

  1. In reality the generated code is a bit more verbose for several reasons. There are more intermediate variables to make the code easier to generate. There is an additional call to next to avoid leaving statements in progress. And finally, we cache the prepared statement in a hash table, instead of preparing it every call. ↩