1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157

use crate::backend::Backend;
use crate::deserialize::{self, FromSql, Queryable, QueryableByName};
use crate::expression::bound::Bound;
use crate::expression::*;
use crate::query_builder::QueryId;
use crate::serialize::{self, IsNull, Output, ToSql};
use crate::sql_types::{is_nullable, HasSqlType, Nullable, SingleValue, SqlType};
use crate::NullableExpressionMethods;

impl<T, DB> HasSqlType<Nullable<T>> for DB
where
    DB: Backend + HasSqlType<T>,
    T: SqlType,
{
    fn metadata(lookup: &mut DB::MetadataLookup) -> DB::TypeMetadata {
        <DB as HasSqlType<T>>::metadata(lookup)
    }
}

impl<T> QueryId for Nullable<T>
where
    T: QueryId + SqlType<IsNull = is_nullable::NotNull>,
{
    type QueryId = T::QueryId;

    const 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,
    ST: SqlType<IsNull = is_nullable::NotNull>,
{
    fn from_sql(bytes: DB::RawValue<'_>) -> deserialize::Result<Self> {
        T::from_sql(bytes).map(Some)
    }

    fn from_nullable_sql(bytes: Option<DB::RawValue<'_>>) -> deserialize::Result<Self> {
        match bytes {
            Some(bytes) => T::from_sql(bytes).map(Some),
            None => Ok(None),
        }
    }
}

impl<T, ST, DB> ToSql<Nullable<ST>, DB> for Option<T>
where
    T: ToSql<ST, DB>,
    DB: Backend,
    ST: SqlType<IsNull = is_nullable::NotNull>,
{
    fn to_sql<'b>(&'b self, out: &mut Output<'b, '_, DB>) -> serialize::Result {
        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: SqlType<IsNull = is_nullable::NotNull>,
    Nullable<ST>: TypedExpressionType,
{
    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: SqlType<IsNull = is_nullable::NotNull>,
    Nullable<ST>: TypedExpressionType,
{
    type Expression = Bound<Nullable<ST>, Self>;

    fn as_expression(self) -> Self::Expression {
        Bound::new(self)
    }
}

impl<T, DB> QueryableByName<DB> for Option<T>
where
    DB: Backend,
    T: QueryableByName<DB>,
{
    fn build<'a>(row: &impl crate::row::NamedRow<'a, DB>) -> deserialize::Result<Self> {
        match T::build(row) {
            Ok(v) => Ok(Some(v)),
            Err(e) if e.is::<crate::result::UnexpectedNullError>() => Ok(None),
            Err(e) => Err(e),
        }
    }
}

impl<ST, T, DB> Queryable<ST, DB> for Option<T>
where
    ST: SingleValue<IsNull = is_nullable::IsNullable>,
    DB: Backend,
    Self: FromSql<ST, DB>,
{
    type Row = Self;

    fn build(row: Self::Row) -> deserialize::Result<Self> {
        Ok(row)
    }
}

impl<T, DB> Selectable<DB> for Option<T>
where
    DB: Backend,
    T: Selectable<DB>,
    crate::dsl::Nullable<T::SelectExpression>: Expression,
{
    type SelectExpression = crate::dsl::Nullable<T::SelectExpression>;

    fn construct_selection() -> Self::SelectExpression {
        T::construct_selection().nullable()
    }
}

#[test]
#[cfg(feature = "postgres")]
fn option_to_sql() {
    use crate::pg::Pg;
    use crate::query_builder::bind_collector::ByteWrapper;
    use crate::sql_types;

    type Type = sql_types::Nullable<sql_types::VarChar>;

    let mut buffer = Vec::new();
    let is_null = {
        let mut bytes = Output::test(ByteWrapper(&mut buffer));
        ToSql::<Type, Pg>::to_sql(&None::<String>, &mut bytes).unwrap()
    };
    assert_eq!(IsNull::Yes, is_null);
    assert!(buffer.is_empty());

    let is_null = {
        let mut bytes = Output::test(ByteWrapper(&mut buffer));
        ToSql::<Type, Pg>::to_sql(&Some(""), &mut bytes).unwrap()
    };
    assert_eq!(IsNull::No, is_null);
    assert!(buffer.is_empty());

    let is_null = {
        let mut bytes = Output::test(ByteWrapper(&mut buffer));
        ToSql::<Type, Pg>::to_sql(&Some("Sean"), &mut bytes).unwrap()
    };
    let expected_bytes = b"Sean".to_vec();
    assert_eq!(IsNull::No, is_null);
    assert_eq!(buffer, expected_bytes);
}