Quick Fix: Postgres decoding for ActiveEnum rs_type Text

[sinder38]

PR Info

• Closes Returning model with enum field with find_by_statement #2423

[sinder38]

@Huliiiiii,
After looking through it I think this should still be part of your #2955 and what I am doing here is more of "quick fix" instead of a real one.

Why:

The rs_type = "String" is the core issue as sea-orm forces all string enums through string at the sqlx layer, losing the type name information at compile time.
sea-orm's DeriveActiveEnum generates:

  impl TryGetable for Tea {
      fn try_get_by(res, idx) {
          let value = String::try_get_by(res, idx)?;  //forces through String
          Tea::try_from_value(&value)
      }
  }

String::type_info() returns PgTypeInfo::TEXT, not PgTypeInfo::with_name("tea"). So compatible() sees "TEXT" != "tea" and so fails.
This fix detects PgTypeKind::Enum at runtime and calls try_get_unchecked to bypass that check.

The proper compile-time fix would be:

The DeriveActiveEnum macro should generate an additional impl when db_type = "Enum" (it's a native PG enum, not a String enum):

  // So, for sqlx-postgres only, when db_type = "Enum":
  #[cfg(feature = "sqlx-postgres")]
  impl sqlx::Type<sqlx::Postgres> for Tea {
      fn type_info() -> sqlx::postgres::PgTypeInfo {
          sqlx::postgres::PgTypeInfo::with_name("tea") 
      }
  }

  #[cfg(feature = "sqlx-postgres")]
  impl<'r> sqlx::Decode<'r, sqlx::Postgres> for Tea {
      fn decode(value: sqlx::postgres::PgValueRef<'r>) -> Result<Self, ...> {
          let s = <&str as sqlx::Decode<sqlx::Postgres>>::decode(value)?;
          Tea::try_from_value(&s.to_owned()).map_err(|e| e.to_string().into())
      }
  }

And then TryGetable for Tea on postgres would call row.try_get::() directly without string intermediate. No runtime check, no try_get_unchecked.

[Huliiiiii]

Yes, I’m trying this solution.

[Huliiiiii]

The fix has been added in #2955.