Implement casting for Vector to HalfVec

Author: A2va

src/diesel_ext/halfvec.rs

@@ -1,11 +1,13 @@
 use diesel::deserialize::{self, FromSql};
+use diesel::expression::{CastsTo, FallibleCastsTo, KnownCastSqlTypeName};
 use diesel::pg::{Pg, PgValue};
 use diesel::query_builder::QueryId;
 use diesel::serialize::{self, IsNull, Output, ToSql};
 use diesel::sql_types::SqlType;
 use std::convert::TryFrom;
 use std::io::Write;
 
+use crate::sql_types::Vector;
 use crate::HalfVector;
 
 #[derive(SqlType, QueryId)]
@@ -32,6 +34,13 @@ impl FromSql<HalfVectorType, Pg> for HalfVector {
     }
 }
 
+impl KnownCastSqlTypeName<Pg> for HalfVectorType {
+    const SQL_TYPE_NAME: &'static str = "halfvec";
+}
+
+impl FallibleCastsTo<HalfVectorType> for Vector {}
+impl CastsTo<HalfVectorType> for Vector {}
+
 #[cfg(test)]
 mod tests {
     use crate::{HalfVector, VectorExpressionMethods};