realm_db_reader/value/
mod.rs

1use chrono::{DateTime, Utc};
2
3use crate::table::Row;
4
5mod from;
6mod into;
7
8pub(crate) const ARRAY_VALUE_KEY: &str = "!ARRAY_VALUE";
9
10// Should match [`crate::spec::ColumnType`]
11/// A single value from a Realm database. Represents one row in one column.
12#[derive(Debug, Clone)]
13pub enum Value {
14    /// A signed integer value. Integers may be nullable in Realm, in which case
15    /// they are represented as [`None`].
16    Int(i64),
17    /// A boolean value. Booleans may be nullable in Realm, in which case
18    /// they are represented as [`None`].
19    Bool(bool),
20    /// A string value. Strings may be nullable in Realm, in which case
21    /// they are represented as [`None`].
22    String(String),
23    /// Currently unsupported.
24    #[doc(hidden)]
25    OldStringEnum(String),
26    /// A binary blob value. Binary blobs may be nullable in Realm, in which case
27    /// they are represented as [`None`].
28    Binary(Vec<u8>),
29    /// A subtable value. Tables in Realm may have a column that contains an
30    /// entire table. In that case, upon loading the row, the subtable and all
31    /// its rows are loaded.
32    Table(Vec<Row<'static>>),
33    /// Currently unsupported.
34    #[doc(hidden)]
35    OldMixed,
36    /// Currently unsupported.
37    #[doc(hidden)]
38    OldDateTime,
39    /// A timestamp value, represented using the `chrono` crate. Timestamps may
40    /// be nullable in Realm, in which case they are represented as [`None`].
41    Timestamp(DateTime<Utc>),
42    /// A floating-point value.
43    Float(f32),
44    /// A double-precision floating-point value.
45    Double(f64),
46    /// Currently unsupported.
47    #[doc(hidden)]
48    Reserved4,
49    /// A link to a row in a given table. If the link is null, it is represented
50    /// as [`None`].
51    Link(Link),
52    /// A list of links to rows in a given table. If a row has no links, this
53    /// will be an empty list.
54    LinkList(Vec<Link>),
55    /// A backlink. In cases where table A maintains a link (see [`Link`] or
56    /// [`LinkList`](`Self::LinkList`)), table B maintains a backlink to table
57    /// A. You can use this to navigate back to the parent row in a has-one
58    /// relationship.
59    ///
60    /// Backlinks may be nullable in Realm, in which case they are represented
61    /// as [`None`].
62    ///
63    /// Backlinks are special, as their containing columns are unnamed, and thus
64    /// cannot be retrieved using [`Row::get`](`crate::Row::get`). Instead, you
65    /// can use [`Row::backlinks`](`crate::Row::backlinks`) to retrieve the
66    /// backlinks. See the documentation for
67    /// [`realm_model!`](`crate::realm_model`) for how to incorporate backlinks
68    /// into your model classes.
69    BackLink(Backlink),
70
71    /// A null value.
72    None,
73}
74
75impl Value {
76    /// Returns true if the value is [`None`].
77    pub fn is_none(&self) -> bool {
78        matches!(self, Value::None)
79    }
80}
81
82/// A link to a single row in a given table.
83#[derive(Debug, Clone, Hash, Eq, PartialEq)]
84pub struct Link {
85    /// The table number of the target table, in the Realm
86    /// [`Group`](`crate::Group`).
87    pub target_table_number: usize,
88    /// The row number this link points to.
89    pub row_number: usize,
90}
91
92impl Link {
93    /// Create a new link to a row in a table.
94    pub fn new(target_table_number: usize, row_number: usize) -> Self {
95        Self {
96            target_table_number,
97            row_number,
98        }
99    }
100}
101
102/// A backlink to one or more rows in a given table. This is the opposite end of
103/// a [`Link`]. Note that [`row_numbers`](`Self::row_numbers`) is guaranteed to
104/// be non-empty. An empty backlink would be represented as [`Value::None`].
105#[derive(Debug, Clone, Hash, Eq, PartialEq)]
106pub struct Backlink {
107    /// The table number of the origin table, in the Realm
108    /// [`Group`](`crate::Group`).
109    pub origin_table_number: usize,
110    /// The column number of the origin column, in the
111    /// [`Table`](`crate::Table`).
112    pub origin_column_number: usize,
113    /// The row numbers this backlink points to, i.e. the rows in the origin
114    /// table that have [`Link`]s to this row.
115    pub row_numbers: Vec<usize>,
116}
117
118impl Backlink {
119    pub fn new(
120        origin_table_number: usize,
121        origin_column_number: usize,
122        row_numbers: Vec<usize>,
123    ) -> Self {
124        Self {
125            origin_table_number,
126            origin_column_number,
127            row_numbers,
128        }
129    }
130}
realm_db_reader/value/mod.rs

realm_db_reader/value/
mod.rs
