connect.rs

use crate::connection::ConnectOptions;
use crate::error::Error;
use crate::executor::Executor;
use crate::{MySqlConnectOptions, MySqlConnection};
use log::LevelFilter;
use sqlx_core::sql_str::AssertSqlSafe;
use sqlx_core::Url;
use std::time::Duration;

impl ConnectOptions for MySqlConnectOptions {
    type Connection = MySqlConnection;

    fn from_url(url: &Url) -> Result<Self, Error> {
        Self::parse_from_url(url)
    }

    fn to_url_lossy(&self) -> Url {
        self.build_url()
    }

    async fn connect(&self) -> Result<Self::Connection, Error>
    where
        Self::Connection: Sized,
    {
        let mut conn = MySqlConnection::establish(self).await?;

        self.configure_session(&mut conn).await?;

        Ok(conn)
    }

    fn log_statements(mut self, level: LevelFilter) -> Self {
        self.log_settings.log_statements(level);
        self
    }

    fn log_slow_statements(mut self, level: LevelFilter, duration: Duration) -> Self {
        self.log_settings.log_slow_statements(level, duration);
        self
    }
}

impl MySqlConnectOptions {
    /// After the connection is established, initialize by configuring
    /// connection parameters (sql_mode, time_zone, charset).
    pub(crate) async fn configure_session(&self, conn: &mut MySqlConnection) -> Result<(), Error> {
        // https://mariadb.com/kb/en/sql-mode/

        // PIPES_AS_CONCAT - Allows using the pipe character (ASCII 124) as string concatenation operator.
        //                   This means that "A" || "B" can be used in place of CONCAT("A", "B").

        // NO_ENGINE_SUBSTITUTION - If not set, if the available storage engine specified by a CREATE TABLE is
        //                          not available, a warning is given and the default storage
        //                          engine is used instead.

        // NO_ZERO_DATE - Don't allow '0000-00-00'. This is invalid in Rust.

        // NO_ZERO_IN_DATE - Don't allow 'YYYY-00-00'. This is invalid in Rust.

        // --

        // Setting the time zone allows us to assume that the output
        // from a TIMESTAMP field is UTC

        // --

        // https://mathiasbynens.be/notes/mysql-utf8mb4

        let mut sql_mode = Vec::new();
        if self.pipes_as_concat {
            sql_mode.push(r#"PIPES_AS_CONCAT"#);
        }
        if self.no_engine_substitution {
            sql_mode.push(r#"NO_ENGINE_SUBSTITUTION"#);
        }

        let mut options = Vec::new();
        if !sql_mode.is_empty() {
            options.push(format!(
                r#"sql_mode=(SELECT CONCAT(@@sql_mode, ',{}'))"#,
                sql_mode.join(",")
            ));
        }

        if let Some(timezone) = &self.timezone {
            options.push(format!(r#"time_zone='{}'"#, timezone));
        }

        if self.set_names {
            // As it turns out, we don't _have_ to set a collation if we don't want to.
            // We can let the server choose the default collation for the charset.
            let set_names = if let Some(collation) = &self.collation {
                format!(r#"NAMES {} COLLATE {collation}"#, self.charset,)
            } else {
                // Leaves the default collation up to the server,
                // but ensures statements and results are encoded using the proper charset.
                format!("NAMES {}", self.charset)
            };

            options.push(set_names);
        }

        if !options.is_empty() {
            conn.execute(AssertSqlSafe(format!(r#"SET {};"#, options.join(","))))
                .await?;
        }

        Ok(())
    }
}