Method query_row_optional

src/sql.rs:528–547

Execute a query which is expected to return zero or one row.

(
        &self,
        sql: &str,
        params: impl rusqlite::Params + Send,
        f: F,
    )

    /// Execute a query which is expected to return zero or one row.
    pub async fn query_row_optional<T, F>(
        &self,
        sql: &str,
        params: impl rusqlite::Params + Send,
        f: F,
    ) -> Result<Option<T>>
    where
        F: Send + FnOnce(&rusqlite::Row) -> rusqlite::Result<T>,
        T: Send + 'static,
    {
        let query_only = true;
        self.call(query_only, move |conn| {
            match conn.query_row(sql.as_ref(), params, f) {
                Ok(res) => Ok(Some(res)),
                Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
                Err(err) => Err(err.into()),
            }
        })
        .await
    }

    /// Executes a query which is expected to return one row and one
    /// column. If the query does not return any rows, returns `Ok(None)`.