插入Postgres时，无法转换为类型为“uuid”的Postgres值

Question

下面是我用来在Postgres数据库中使用postgres crate插入数据的代码（不幸的是不存在于Rust Playground中）：

使用以下Cargo.toml：

[package]
name = "suff-import"
version = "0.1.0"
authors = ["greg"]

[dependencies]
csv = "1"
postgres = "0.15"
uuid = "0.7"

文件main.rs：

extern crate csv;
extern crate postgres;
extern crate uuid;

use uuid::Uuid;
use postgres::{Connection, TlsMode};
use std::error::Error;
use std::io;
use csv::StringRecord;

struct Stuff {
    stuff_id: Uuid,
    created_at: String,
    description: String,
    is_something: bool,
}

impl Stuff {
    fn from_string_record(record: StringRecord) -> Stuff {
        Stuff {
            stuff_id: Uuid::parse_str(record.get(0).unwrap()).unwrap(),
            created_at: record.get(1).unwrap().to_string(),
            description: record.get(2).unwrap().to_string(),
            is_something: record.get(3).unwrap().to_string().parse::<i32>().unwrap() == 2,
        }
    }
}

fn save_row(dbcon: &Connection, stuff: Stuff) -> Result<(), Box<Error>> {
    dbcon.execute(
        "insert into public.stuff (stuff_id, created_at, description, is_something) values ($1::uuid, $2, $3, $4)",
        &[&format!("{}", &stuff.stuff_id).as_str(), &stuff.created_at, &stuff.description, &stuff.is_something]
    )?;
    Ok(())
}


fn import() -> Result<(), Box<Error>> {
    let mut reader = csv::Reader::from_reader(io::stdin());
    let dbcon = Connection::connect("postgres://[email protected]/gregoire", TlsMode::None).unwrap();

    for result in reader.records() {
        let record = result?;
        println!(".");
        save_row(&dbcon, Stuff::from_string_record(record))?;
    }

    Ok(())
}

fn main() {
    if let Err(error) = import() {
        println!("There were some errors: {}", error);
        std::process::exit(1);
    }
}

程序编译，但在运行时出现错误消息：

./target/debug/suff-import <<EOF
stuff_id,created_at,description,is_something
5252fff5-d04f-4e0f-8d3e-27da489cf40c,"2019-03-15 16:39:32","This is a description",1
EOF
.
There were some errors: type conversion error: cannot convert to or from a Postgres value of type `uuid`

我测试了使用&str宏将UUID转换为format!，因为Postgres应该隐式地转换为UUID，但它不起作用（相同的错误消息）。然后我在Postgres查询中添加了一个显式的$1::uuid，但问题仍然存在。

Answer 1

crate page说：

可选功能

UUID type

Qazxswpoi功能可选择提供UUID支持，为with-uuid的ToSql类型添加FromSql和uuid实现。需要Uuid版本0.5。

您尚未指定该功能，并且您使用的是不兼容的uuid版本。

Cargo.toml

uuid

数据库设置

[package]
name = "repro"
version = "0.1.0"
edition = "2018"

[dependencies]
postgres = { version = "0.15.2", features = ["with-uuid"] }
uuid = "0.5"

码

CREATE TABLE junk (id uuid);

也可以看看：

• use postgres::{Connection, TlsMode};
  use std::error::Error;
  use uuid::Uuid;
  
  fn main() -> Result<(), Box<Error>> {
      let conn = Connection::connect(
          "postgresql://shep@localhost:5432/stackoverflow",
          TlsMode::None,
      )
      .unwrap();
  
      let stuff_id = Uuid::default();
  
      conn.execute(
          "insert into public.junk (id) values ($1)",
          &[&stuff_id],
      )?;
  
      Ok(())
  }