postgres-from-row

派生FromRow以在结构体和PostgreSQL行之间生成映射。

此crate与postgres和tokio-postgres都兼容。

[dependencies]
postgres_from_row = "0.5.2"

示例

use postgres_from_row::FromRow;

#[derive(FromRow)]
struct Todo {
    todo_id: i32,
    text: String
    author_id: i32,
}

let row = client.query_one("SELECT todo_id, text, author_id FROM todos", &[]).unwrap();

// Pass a row with the correct columns.
let todo = Todo::from_row(&row);

let row = client.query_one("SELECT foo FROM bar", &[]).unwrap();

// Use `try_from_row` if the operation could fail.
let todo = Todo::try_from_row(&row);
assert!(todo.is_err());

每个字段都需要实现postgres::types::FromSql，因为这将用于将单个列转换为指定的类型。如果您想覆盖此行为并将其委托给也实现了FromRow的嵌套结构，请使用#[from_row]

use postgres_from_row::FromRow;

#[derive(FromRow)]
struct Todo {
    todo_id: i32,
    text: String,
    #[from_row(flatten)]
    author: User
}

#[derive(FromRow)]
struct User {
    user_id: i32,
    username: String
}

let row = client.query_one("SELECT todo_id, text, user_id, username FROM todos t, users u WHERE t.author_id = u.user_id", &[]).unwrap();
let todo = Todo::from_row(&row);

struct Todo {
    // If the postgres column is named `todo_id`.
    #[from_row(rename = "todo_id")]
    id: i32,
    // If the postgres column is `VARCHAR`, it will be decoded to `String`,
    // using `FromSql` and then converted to `Vec<u8>` using `std::convert::From`.
    #[from_row(from = "String")]
    todo: Vec<u8>
}