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use std::error::Error; use std::fmt; use std::io::Write; use backend::Backend; use expression::*; use expression::bound::Bound; use query_builder::QueryId; use query_source::Queryable; use types::{HasSqlType, FromSql, FromSqlRow, Nullable, ToSql, ToSqlOutput, IsNull, NotNull}; impl<T, DB> HasSqlType<Nullable<T>> for DB where DB: Backend + HasSqlType<T>, T: NotNull, { fn metadata(lookup: &DB::MetadataLookup) -> DB::TypeMetadata { <DB as HasSqlType<T>>::metadata(lookup) } fn row_metadata(out: &mut Vec<DB::TypeMetadata>, lookup: &DB::MetadataLookup) { <DB as HasSqlType<T>>::row_metadata(out, lookup) } } impl<T> QueryId for Nullable<T> where T: QueryId + NotNull, { type QueryId = T::QueryId; fn has_static_query_id() -> bool { T::has_static_query_id() } } impl<T, ST, DB> FromSql<Nullable<ST>, DB> for Option<T> where T: FromSql<ST, DB>, DB: Backend + HasSqlType<ST>, ST: NotNull, { fn from_sql(bytes: Option<&DB::RawValue>) -> Result<Self, Box<Error+Send+Sync>> { match bytes { Some(_) => T::from_sql(bytes).map(Some), None => Ok(None) } } } impl<T, ST, DB> Queryable<Nullable<ST>, DB> for Option<T> where T: Queryable<ST, DB>, DB: Backend + HasSqlType<ST>, Option<T::Row>: FromSqlRow<Nullable<ST>, DB>, ST: NotNull, { type Row = Option<T::Row>; fn build(row: Self::Row) -> Self { row.map(T::build) } } impl<T, ST, DB> FromSqlRow<Nullable<ST>, DB> for Option<T> where T: FromSqlRow<ST, DB>, DB: Backend + HasSqlType<ST>, ST: NotNull, { fn build_from_row<R: ::row::Row<DB>>(row: &mut R) -> Result<Self, Box<Error+Send+Sync>> { let fields_needed = Self::fields_needed(); if row.next_is_null(fields_needed) { row.advance(fields_needed); Ok(None) } else { T::build_from_row(row).map(Some) } } fn fields_needed() -> usize { T::fields_needed() } } impl<T, ST, DB> ToSql<Nullable<ST>, DB> for Option<T> where T: ToSql<ST, DB>, DB: Backend + HasSqlType<ST>, ST: NotNull, { fn to_sql<W: Write>(&self, out: &mut ToSqlOutput<W, DB>) -> Result<IsNull, Box<Error+Send+Sync>> { if let Some(ref value) = *self { value.to_sql(out) } else { Ok(IsNull::Yes) } } } impl<T, ST> AsExpression<Nullable<ST>> for Option<T> where ST: NotNull, { type Expression = Bound<Nullable<ST>, Self>; fn as_expression(self) -> Self::Expression { Bound::new(self) } } impl<'a, T, ST> AsExpression<Nullable<ST>> for &'a Option<T> where ST: NotNull, { type Expression = Bound<Nullable<ST>, Self>; fn as_expression(self) -> Self::Expression { Bound::new(self) } } #[derive(Debug)] pub struct UnexpectedNullError { pub msg: String, } impl fmt::Display for UnexpectedNullError { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "{}", self.msg) } } impl Error for UnexpectedNullError { fn description(&self) -> &str { &self.msg } } #[cfg(all(test, feature = "postgres"))] use types; #[cfg(all(test, feature = "postgres"))] use pg::Pg; #[test] #[cfg(feature = "postgres")] fn option_to_sql() { type Type = types::Nullable<types::VarChar>; let mut bytes = ToSqlOutput::test(); let is_null = ToSql::<Type, Pg>::to_sql(&None::<String>, &mut bytes).unwrap(); assert_eq!(IsNull::Yes, is_null); assert!(bytes.is_empty()); let is_null = ToSql::<Type, Pg>::to_sql(&Some(""), &mut bytes).unwrap(); assert_eq!(IsNull::No, is_null); assert!(bytes.is_empty()); let is_null = ToSql::<Type, Pg>::to_sql(&Some("Sean"), &mut bytes).unwrap(); let expectd_bytes = b"Sean".to_vec(); assert_eq!(IsNull::No, is_null); assert_eq!(bytes, expectd_bytes); }