native_db 0.8.2

Drop-in embedded database
Documentation 
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

use crate::db_type::{KeyOptions, Result, ToInput, ToKeyDefinition};
use crate::transaction::internal::private_readable_transaction::PrivateReadableTransaction;
use crate::transaction::internal::r_transaction::InternalRTransaction;
use crate::transaction::internal::rw_transaction::InternalRwTransaction;

/// Get the number of values in the database.
pub struct RLen<'db, 'txn> {
    pub(crate) internal: &'txn InternalRTransaction<'db>,
}

impl RLen<'_, '_> {
    /// Get the number of values.
    ///
    /// # Example
    /// ```rust
    /// use native_db::*;
    /// use native_model::{native_model, Model};
    /// use serde::{Deserialize, Serialize};
    ///
    /// #[derive(Serialize, Deserialize)]
    /// #[native_model(id=1, version=1)]
    /// #[native_db]
    /// struct Data {
    ///     #[primary_key]
    ///     id: u64,
    /// }
    ///
    /// fn main() -> Result<(), db_type::Error> {
    ///     let mut models = Models::new();
    ///     models.define::<Data>()?;
    ///     let db = Builder::new().create_in_memory(&models)?;
    ///     
    ///     // Open a read transaction
    ///     let r = db.r_transaction()?;
    ///     
    ///     // Get all values
    ///     let _number:u64 = r.len().primary::<Data>()?;
    ///     Ok(())
    /// }
    /// ```
    pub fn primary<T: ToInput>(&self) -> Result<u64> {
        let model = T::native_db_model();
        let result = self.internal.primary_len(model)?;
        Ok(result)
    }

    /// Get the number of values by secondary key.
    ///
    /// Anatomy of a secondary key it is a `enum` with the following structure: `<table_name>Key::<name>`.
    ///
    /// If the secondary key is [`optional`](struct.Builder.html#optional) you will
    /// get all values that have the secondary key set.
    ///
    /// # Example
    /// ```rust
    /// use native_db::*;
    /// use native_model::{native_model, Model};
    /// use serde::{Deserialize, Serialize};
    ///
    /// #[derive(Serialize, Deserialize)]
    /// #[native_model(id=1, version=1)]
    /// #[native_db]
    /// struct Data {
    ///    #[primary_key]
    ///    id: u64,
    ///    #[secondary_key(optional)]
    ///    name: Option<String>,
    /// }
    ///
    ///
    /// fn main() -> Result<(), db_type::Error> {
    ///    let mut models = Models::new();
    ///     models.define::<Data>()?;
    ///     let db = Builder::new().create_in_memory(&models)?;
    ///     
    ///     // Open a read transaction
    ///     let r = db.r_transaction()?;
    ///     
    ///     // Get the number of values with the secondary key set
    ///     let _number:u64 = r.len().secondary::<Data>(DataKey::name)?;
    ///     Ok(())
    /// }
    /// ```
    pub fn secondary<T: ToInput>(&self, key_def: impl ToKeyDefinition<KeyOptions>) -> Result<u64> {
        let model = T::native_db_model();
        let result = self.internal.secondary_len(model, key_def)?;
        Ok(result)
    }
}

pub struct RwLen<'db, 'txn> {
    pub(crate) internal: &'txn InternalRwTransaction<'db>,
}

impl RwLen<'_, '_> {
    /// Get the number of values.
    ///
    /// Same as [`RLen::primary()`](struct.RLen.html#method.primary).
    pub fn primary<T: ToInput>(&self) -> Result<u64> {
        let model = T::native_db_model();
        let result = self.internal.primary_len(model)?;
        Ok(result)
    }

    /// Get the number of values by secondary key.
    ///
    /// Same as [`RLen::secondary()`](struct.RLen.html#method.secondary).
    pub fn secondary<T: ToInput>(&self, key_def: impl ToKeyDefinition<KeyOptions>) -> Result<u64> {
        let model = T::native_db_model();
        let result = self.internal.secondary_len(model, key_def)?;
        Ok(result)
    }
}