rusqlite/src/convenient.rs

use {Error, Result, Row, Statement};
use types::ToSql;

impl<'conn> Statement<'conn> {
    /// Execute an INSERT and return the ROWID.
    ///
    /// # Note
    ///
    /// This function is a convenience wrapper around `execute()` intended for queries that
    /// insert a single item. It is possible to misuse this function in a way that it cannot
    /// detect, such as by calling it on a statement which _updates_ a single item rather than
    /// inserting one. Please don't do that.
    ///
    /// # Failure
    ///
    /// Will return `Err` if no row is inserted or many rows are inserted.
    pub fn insert(&mut self, params: &[&ToSql]) -> Result<i64> {
        let changes = try!(self.execute(params));
        match changes {
            1 => Ok(self.conn.last_insert_rowid()),
            _ => Err(Error::StatementChangedRows(changes)),
        }
    }

    /// Return `true` if a query in the SQL statement it executes returns one or more rows
    /// and `false` if the SQL returns an empty set.
    pub fn exists(&mut self, params: &[&ToSql]) -> Result<bool> {
        let mut rows = try!(self.query(params));
        let exists = {
            match rows.next() {
                Some(_) => true,
                None => false,
            }
        };
        Ok(exists)
    }

    /// Convenience method to execute a query that is expected to return a single row.
    ///
    /// If the query returns more than one row, all rows except the first are ignored.
    ///
    /// # Failure
    ///
    /// Will return `Err` if the underlying SQLite call fails.
    pub fn query_row<T, F>(&mut self, params: &[&ToSql], f: F) -> Result<T>
        where F: FnOnce(&Row) -> T
    {
        let mut rows = try!(self.query(params));

        rows.get_expected_row().map(|r| f(&r))
    }
}

#[cfg(test)]
mod test {
    use {Connection, Error, Result};

    #[test]
    fn test_insert() {
        let db = Connection::open_in_memory().unwrap();
        db.execute_batch("CREATE TABLE foo(x INTEGER UNIQUE)").unwrap();
        let mut stmt = db.prepare("INSERT OR IGNORE INTO foo (x) VALUES (?)").unwrap();
        assert_eq!(stmt.insert(&[&1i32]).unwrap(), 1);
        assert_eq!(stmt.insert(&[&2i32]).unwrap(), 2);
        match stmt.insert(&[&1i32]).unwrap_err() {
            Error::StatementChangedRows(0) => (),
            err => panic!("Unexpected error {}", err),
        }
        let mut multi = db.prepare("INSERT INTO foo (x) SELECT 3 UNION ALL SELECT 4").unwrap();
        match multi.insert(&[]).unwrap_err() {
            Error::StatementChangedRows(2) => (),
            err => panic!("Unexpected error {}", err),
        }
    }

    #[test]
    fn test_insert_different_tables() {
        // Test for https://github.com/jgallagher/rusqlite/issues/171
        let db = Connection::open_in_memory().unwrap();
        db.execute_batch(r"
            CREATE TABLE foo(x INTEGER);
            CREATE TABLE bar(x INTEGER);
        ")
            .unwrap();

        assert_eq!(db.prepare("INSERT INTO foo VALUES (10)").unwrap().insert(&[]).unwrap(),
                   1);
        assert_eq!(db.prepare("INSERT INTO bar VALUES (10)").unwrap().insert(&[]).unwrap(),
                   1);
    }

    #[test]
    fn test_exists() {
        let db = Connection::open_in_memory().unwrap();
        let sql = "BEGIN;
                   CREATE TABLE foo(x INTEGER);
                   INSERT INTO foo VALUES(1);
                   INSERT INTO foo VALUES(2);
                   END;";
        db.execute_batch(sql).unwrap();
        let mut stmt = db.prepare("SELECT 1 FROM foo WHERE x = ?").unwrap();
        assert!(stmt.exists(&[&1i32]).unwrap());
        assert!(stmt.exists(&[&2i32]).unwrap());
        assert!(!stmt.exists(&[&0i32]).unwrap());
    }

    #[test]
    fn test_query_row() {
        let db = Connection::open_in_memory().unwrap();
        let sql = "BEGIN;
                   CREATE TABLE foo(x INTEGER, y INTEGER);
                   INSERT INTO foo VALUES(1, 3);
                   INSERT INTO foo VALUES(2, 4);
                   END;";
        db.execute_batch(sql).unwrap();
        let mut stmt = db.prepare("SELECT y FROM foo WHERE x = ?").unwrap();
        let y: Result<i64> = stmt.query_row(&[&1i32], |r| r.get(0));
        assert_eq!(3i64, y.unwrap());
    }
}