Cannot use UUID as a primary key: Uuid: diesel::Expression is not satisfied

Question

I want to have a UUID field as the primary field in a Postgres table, but I get the following error:

error[E0277]: the trait bound `uuid::Uuid: diesel::Expression` is not satisfied
 --> database/src/models.rs:3:35
  |
3 | #[derive(Debug, Clone, Queryable, Insertable)]
  |                                   ^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `uuid::Uuid`
  |
  = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::sql_types::Uuid>` for `uuid::Uuid`

Some older questions are there about UUID with diesel but none of them are insertable and I am getting the error specifically in that. I am using diesel with actix web.

Here is my model:

use crate::schema::users;

#[derive(Debug, Clone, Queryable, Insertable)]
#[table_name="users"]
pub struct User {
    pub id: uuid::Uuid,
    pub phone: String,
    pub name: String,
    pub password: String,
}

And my table schema

table! {
    users (id) {
        id -> Uuid,
        name -> Text,
        phone -> Text,
        password -> Text,
    }
}

I found some old post that suggested that the field might be nullable but id is the PRIMARY KEY in my table up.sql, so it is not nullable.

The table is generated from diesel-cli, do there doesn't seem to be any problem there.

Here is my Cargo.toml

diesel = { version = "1.0.0", features = ["postgres", "r2d2", "uuid"] }
uuid = { version = "0.8", features = ["v4"] }
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"

Could you add some more information about which version of `diesel` and `uuid ` you use? Also which feature flags are enabled for `diesel`? This is very likely either a missing feature flag or a version mismatch between the `uuid` version `diesel` uses internally and your `uuid` version. — weiznich, Feb 28 '20 at 10:01
Diesel does currently not support `uuid` version 0.8 in it's latest released version, only version 0.7 and below are supported. Additionally you need to use the `uuidv07` feature for support for version 0.7. This will change with the next diesel release. — weiznich, Mar 02 '20 at 22:28

score 7 · Accepted Answer · answered Mar 25 '20 at 12:00

It's always good to see what's in your Cargo.lock file and look are pointing for package dependencies.

[[package]]
name = "diesel"
version = "1.4.4"
...
 "uuid 0.6.5", <-- It was older version even I've installed newest version of uuid
]

as soon as change features to uuidv07 and run cargo update Cargo.lock file also changes. If you want to check which Uuid is applied by diesel. It's possible checking it by looking to the source of the diesel::sql_types::Uuid to be sure they are using the same versions as uuid::Uuid.

P.S: Answer was commented by @weiznich in the question post, just adding little bit detailed information and as an answer post whom, who not read comments and look for answer only

I am a beginner, uuid inside diesel is a peer-dependency I guess, but why it cause this since it is different from the main cargo.toml — Ping Woo, Jan 20 '21 at 05:06

Cannot use UUID as a primary key: Uuid: diesel::Expression is not satisfied

1 Answers1