问题
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"]
回答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,
}
来源:https://stackoverflow.com/questions/53326887/rust-diesel-how-to-query-and-insert-into-postgres-tables-which-have-uuid