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
use super::{
data_type::DataType,
sql_char::{DecodingError, SqlChar, slice_to_utf8},
};
/// Indication of whether a column is nullable or not.
#[derive(Clone, Copy, Hash, Debug, Eq, PartialEq, Default)]
pub enum Nullability {
/// Indicates that we do not know whether the column is Nullable or not.
#[default]
Unknown,
/// The column may hold NULL values.
Nullable,
/// The column can not hold NULL values.
NoNulls,
}
impl Nullability {
/// Construct a new instance from a `Nullability` new type constant.
///
/// ```
/// use odbc_api::Nullability;
///
/// assert_eq!(Nullability::Unknown, Nullability::new(odbc_sys::Nullability::UNKNOWN));
/// assert_eq!(Nullability::NoNulls, Nullability::new(odbc_sys::Nullability::NO_NULLS));
/// assert_eq!(Nullability::Nullable, Nullability::new(odbc_sys::Nullability::NULLABLE));
/// ```
pub fn new(nullability: odbc_sys::Nullability) -> Self {
match nullability {
odbc_sys::Nullability::UNKNOWN => Nullability::Unknown,
odbc_sys::Nullability::NO_NULLS => Nullability::NoNulls,
odbc_sys::Nullability::NULLABLE => Nullability::Nullable,
other => panic!("ODBC returned invalid value for Nullable: {}", other.0),
}
}
/// `true` if the column is `Nullable` or it is not know whether the column is nullable. `false`
/// if and only if the column is `NoNulls`.
pub fn could_be_nullable(&self) -> bool {
match self {
Nullability::Nullable | Nullability::Unknown => true,
Nullability::NoNulls => false,
}
}
}
/// Describes the type and attributes of a column.
#[derive(Clone, Debug, Eq, PartialEq, Default)]
pub struct ColumnDescription {
/// Column name. May be empty if unavailable.
pub name: Vec<SqlChar>,
/// Type of the column
pub data_type: DataType,
/// Indicates whether the column is nullable or not.
pub nullability: Nullability,
}
impl ColumnDescription {
/// In production, an 'empty' [`ColumnDescription`] is expected to be constructed via the
/// [`Default`] trait. It is then filled using [`crate::ResultSetMetadata::describe_col`]. When
/// writing test cases however it might be desirable to directly instantiate a
/// [`ColumnDescription`]. This constructor enables you to do that, without caring which type
/// `SqlChar` resolves to.
pub fn new(name: &str, data_type: DataType, nullability: Nullability) -> Self {
#[cfg(not(any(feature = "wide", all(not(feature = "narrow"), target_os = "windows"))))]
pub fn utf8_to_vec_char(text: &str) -> Vec<u8> {
text.to_owned().into_bytes()
}
#[cfg(any(feature = "wide", all(not(feature = "narrow"), target_os = "windows")))]
pub fn utf8_to_vec_char(text: &str) -> Vec<u16> {
use widestring::U16String;
U16String::from_str(text).into_vec()
}
Self {
name: utf8_to_vec_char(name),
data_type,
nullability,
}
}
/// Converts the internal UTF16 representation of the column name into UTF8 and returns the
/// result as a `String`.
pub fn name_to_string(&self) -> Result<String, DecodingError> {
slice_to_utf8(&self.name)
}
/// `true` if the column is `Nullable` or it is not know whether the column is nullable. `false`
/// if and only if the column is `NoNulls`.
pub fn could_be_nullable(&self) -> bool {
self.nullability.could_be_nullable()
}
}
#[cfg(test)]
mod tests {
use crate::Nullability;
/// Application should panic if ODBC driver returns unsupported value for nullable
#[test]
#[should_panic(expected = "ODBC returned invalid value for Nullable: 5")]
fn invalid_nullable_representation() {
Nullability::new(odbc_sys::Nullability(5));
}
}