Calling `PgConnectOptions.options` with >1 elements results in invalid arguments.

[kevincox]

	let mut connect_options = url.parse::<sqlx::postgres::PgConnectOptions>().unwrap()
		.options([
			("default_transaction_isolation", "serializable"),
			("idle_in_transaction_session_timeout", "5min"),
		]);

thread 'main' panicked at 'Couldn't connect to database.: Database(PgDatabaseError { severity: Fatal, code: "22023", message: "invalid value for parameter \"default_transaction_isolation\": \"serializable-c\"", detail: None, hint: Some("Available values: serializable, repeatable read, read committed, read uncommitted."), position: None, where: None, schema: None, table: None, column: None, data_type: None, constraint: None, file: Some("guc.c"), line: Some(6873), routine: Some("parse_and_validate_value") })', src/db.rs:23:14

This bug appears to have existed forever: #1539 (comment)

[kevincox]

The workaround is to make multiple calls:

	let mut connect_options = url.parse::<sqlx::postgres::PgConnectOptions>().unwrap()
		.options([("default_transaction_isolation", "serializable")])
		.options([("idle_in_transaction_session_timeout", "5min")]);

[abonander]

This bug appears to have existed forever:

The options() method has only existed since November. However, the fix should be pretty easy, and would simplify the method quite a bit.

I'd replace the following lines: https://github.com/launchbadge/sqlx/blob/master/sqlx-core/src/postgres/options/mod.rs#L354-L363

With this:

use std::fmt::Write;

for (k, v) in options {
    // Do this in here so `options_str` is only set if we have an option to insert
    let mut options_str = self.options.get_or_insert_with(String::new);

    if !options_str.is_empty() {
        options_str.push(' ');
    }

    write!(options_str, "-c {}={}", k, v).expect("failed to write an option to the string");
}

[kevincox]

I meant since the introduction of the feature, so relatively low priority as it wasn't something newly broken.

I agree, that would clean up the code a lot.

[liushuyu]

A fix is proposed in #1731.