porm 0.1.0

SQL first ORM for PostgreSQL
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
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134

//! Migration management.
pub use self::logger::*;

use std::fmt::{Display, Formatter};
use tokio_postgres::Client;
use tokio_postgres::error::SqlState;

mod logger;

/// Migrate database to latest version.
///
/// `history_table` is the name of table to store migrations history so it should be hard-coded.
/// This table will be created automatically if not exists.
///
/// `migrations` can be obtained from the code that was generated with
/// [porm-parser](https://crates.io/crates/porm-parser).
///
/// # Warning
/// All queries on `history_table` will be construct with [format] macro. That mean `history_table`
/// should not come from untrusted source.
pub async fn migrate(
    client: &Client,
    mut logger: impl Logger,
    history_table: &str,
    migrations: &[Migration],
) -> Result<(), Error> {
    // Get current version.
    let mut sql = format!("SELECT version FROM {history_table} ORDER BY version DESC LIMIT 1");
    let current: Option<i32> = match client.query_opt_scalar(&sql, &[]).await {
        Ok(v) => v,
        Err(e) if e.code() == Some(&SqlState::UNDEFINED_TABLE) => {
            logger.create_history_table(history_table);

            sql = format!(
                "CREATE TABLE {history_table} (version integer NOT NULL, name text, applied_time timestamp with time zone NOT NULL, PRIMARY KEY (version))"
            );

            client
                .batch_execute(&sql)
                .await
                .map_err(Error::CreateHistoryTable)?;

            None
        }
        Err(e) => return Err(Error::QueryVersion(e)),
    };

    // Apply migrations.
    let current = current
        .map(usize::try_from)
        .transpose()
        .map_err(|_| Error::InvalidVersion)?;
    let next = current.map(|v| v + 1).unwrap_or(0);
    let sql =
        format!("INSERT INTO {history_table} (version, name, applied_time) VALUES ($1, $2, now())");

    logger.start(current);

    for next in next.. {
        let m = match migrations.get(next) {
            Some(v) => v,
            None => break,
        };

        logger.run(m.name, next);

        client
            .batch_execute(m.script)
            .await
            .map_err(|e| Error::ExecuteMigration(m.name, next, e))?;

        // Update version.
        let version = i32::try_from(next).unwrap();

        client
            .execute(&sql, &[&version, &m.name])
            .await
            .map_err(|e| Error::UpdateVersion(m.name, next, e))?;
    }

    Ok(())
}

/// Contains information for a migration.
pub struct Migration {
    /// Name of migration.
    pub name: Option<&'static str>,
    /// SQL statements for the migration.
    pub script: &'static str,
}

/// Reason when failed to apply SQL migrations.
#[derive(Debug)]
pub enum Error {
    /// Couldn't create table for migrations history.
    CreateHistoryTable(tokio_postgres::Error),
    /// Couldn't query database version.
    QueryVersion(tokio_postgres::Error),
    /// Current database version is invalid.
    InvalidVersion,
    /// Couldn't execute migration.
    ExecuteMigration(Option<&'static str>, usize, tokio_postgres::Error),
    /// Couldn't update database version.
    UpdateVersion(Option<&'static str>, usize, tokio_postgres::Error),
}

impl std::error::Error for Error {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            Self::CreateHistoryTable(e) => Some(e),
            Self::QueryVersion(e) => Some(e),
            Self::InvalidVersion => None,
            Self::ExecuteMigration(_, _, e) => Some(e),
            Self::UpdateVersion(_, _, e) => Some(e),
        }
    }
}

impl Display for Error {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::CreateHistoryTable(_) => {
                write!(f, "couldn't create table for migrations history")
            }
            Self::QueryVersion(_) => f.write_str("couldn't query database version"),
            Self::InvalidVersion => f.write_str("current database version is invalid"),
            Self::ExecuteMigration(n, v, _) => match n {
                Some(n) => write!(f, "couldn't execute migration {n}"),
                None => write!(f, "couldn't execute migration for version {v}"),
            },
            Self::UpdateVersion(_, v, _) => write!(f, "couldn't update database version to {v}"),
        }
    }
}