PostgreSQL query fails with `no binary input function available for type semver`

[xanderio]

As discussed in #1269 sqlx always sends it's query in binary mode.
The semver type however doesn't have binary input/output function. This make interacting with this extension quite cumbersome.

Link to extension: https://github.com/theory/pg-semver

[abonander]

I think we might be able to work this in to the Type derive, maybe something like:

#[derive(sqlx::Type)]
#[sqlx(transparent, type_name = "semver", pg_format = "text")]
pub struct Semver(pub semver::Version);

So specifying #[sqlx(pg_format = "text")] would tell the derived Encode impl to use Display and the derived Decode impl to use FromStr for the wrapped type, and then tell Postgres that we want to send/receive the type in text format. That would even let you use String as the inner type if you didn't really care otherwise.

On the output side, when we resolve a PgType::DeclareWithName() to PgType::CustomType(), we can also check if the type has a typsend of 0 (which means there's no function to generate the wire encoding) and store that as a flag like text_only. And then when we create a portal with the Bind message, we set the format to be text for any column with a text_only type.

[anna-is-cute]

Have there been any developments on this issue? I would love a way to use the semver extension with sqlx.