Rust/Diesel：如何查询并插入具有 uuid 的 postgres 表

Question

I have the following schema generated by Diesel:

table! {
user (id) {
    id -> Uuid,
    name -> Text
}

and the associated model

use diesel::{
    self,
    Queryable,
    Insertable,
};
use diesel::prelude::*;
use diesel::sql_types::Uuid;
use super::schema::user;

#[derive(Queryable)]
pub struct User {
    pub id: Uuid,
    pub name: String,
}

impl User {

    pub fn get(id: i32, connection: &PgConnection) -> Vec<User> {
        user::table.load::<User>(connection).unwrap()
    }
}

I get an error when I try to compile this which says:

21 |         user::table.load::<User>(connection).unwrap()                                                                                                                              
   |                         ^^^^ the trait `diesel::Queryable<diesel::sql_types::Uuid, diesel::pg::Pg>` is not implemented for `diesel::sql_types::Uuid` 

If I try to insert I get a similar error saying that Expression is not implemented.

Could this be a problem with my dependencies or something I may have forgotten to add to the model?

[dependencies]
rocket = "0.4.0-rc.1"
serde = "1.0"
serde_derive = "1.0"
serde_json = "1.0"
diesel = { version = "1.0.0", features = ["postgres", "uuid"] }
r2d2 = "*"
r2d2-diesel = "*"

[dependencies.rocket_contrib]
version = "0.4.0-rc.1"
default-features = false
features = ["json", "diesel_postgres_pool", "uuid"]

Answer 1

The type in the struct needs to be a Rust type rather than a SQL type, specifically Uuid from the uuid crate (in Diesel 1.3, only version 0.6 is supported by Diesel). In the code from the question, the Uuid is expanded to a diesel::sql_types::Uuid

#[derive(Queryable)]
pub struct User {
    pub id: uuid::Uuid,
    pub name: String,
}

Answer 2

Just spent a lot of time with this problem as well. It looks like as of Diesel 1.4.5, you can add the latest version of uuid , but you have to specify the uuidv07 feature on Diesel.

Your Cargo.toml should look something like this:

uuid = { version = "0.8.2", features = ["serde", "v4"] }
diesel = { version = "1.4.5", features = ["chrono", "postgres", "r2d2", "uuidv07"] }

Source: https://github.com/diesel-rs/diesel/issues/2348

Note: Also, like @canab said, the Uuid type on the struct should be from the uuid library, not the Diesel SQL type.