Issue with Diesel and Rust Traits

Question

I'm trying to use the Diesel crate (version 2.1.3; rustc 1.73.0) for an application and have some code that goes like this:

src/models/user.rs

use chrono::NaiveDateTime;
use diesel::prelude::*;
use juniper::GraphQLObject;
use uuid::Uuid;

use crate::{db::get_connection, schema::users};

#[derive(Debug, GraphQLObject, Identifiable, Queryable, AsChangeset, Clone)]
#[diesel(table_name = users)]
#[graphql(description = "A user")]
pub struct UserModel {
    pub id: Uuid,
    pub created_at: NaiveDateTime,
    pub updated_at: NaiveDateTime,
    pub email: String,
}

impl UserModel {
    pub fn get_latest() -> QueryResult<UserModel> {
        let mut con = get_connection();
        use crate::schema::users::dsl::*;

        users
            .order(created_at.desc())
            .limit(1)
            .get_result(&mut *con)
    }
}

src/schema.rs

diesel::table! {
    users (id) {
        id -> Uuid,
        created_at -> Timestamp,
        updated_at -> Timestamp,
        #[max_length = 120]
        email -> Varchar,
    }
}

However, this will not compile. The following errors are thrown when I try:

error[E0277]: the trait bound `(uuid::Uuid, chrono::NaiveDateTime, chrono::NaiveDateTime, std::string::String): diesel::deserialize::FromStaticSqlRow<(diesel::sql_types::Uuid, diesel::sql_types::Timestamp, diesel::sql_types::Timestamp, diesel::sql_types::Text), diesel::pg::Pg>` is not satisfied
    --> src/models/user.rs:26:25
     |
26   |             .get_result(&mut *con)
     |              ---------- ^^^^^^^^^ the trait `diesel::deserialize::FromStaticSqlRow<(diesel::sql_types::Uuid, diesel::sql_types::Timestamp, diesel::sql_types::Timestamp, diesel::sql_types::Text), diesel::pg::Pg>` is not implemented for `(uuid::Uuid, chrono::NaiveDateTime, chrono::NaiveDateTime, std::string::String)`
     |              |
     |              required by a bound introduced by this call
     |
     = help: the following other types implement trait `diesel::deserialize::FromStaticSqlRow<ST, DB>`:
               <(T0,) as diesel::deserialize::FromStaticSqlRow<(ST0,), __DB>>
               <(T1, T0) as diesel::deserialize::FromStaticSqlRow<(ST1, ST0), __DB>>
               <(T1, T2, T0) as diesel::deserialize::FromStaticSqlRow<(ST1, ST2, ST0), __DB>>
               <(T1, T2, T3, T0) as diesel::deserialize::FromStaticSqlRow<(ST1, ST2, ST3, ST0), __DB>>
               <(T1, T2, T3, T4, T0) as diesel::deserialize::FromStaticSqlRow<(ST1, ST2, ST3, ST4, ST0), __DB>>
               <(T1, T2, T3, T4, T5, T0) as diesel::deserialize::FromStaticSqlRow<(ST1, ST2, ST3, ST4, ST5, ST0), __DB>>
               <(T1, T2, T3, T4, T5, T6, T0) as diesel::deserialize::FromStaticSqlRow<(ST1, ST2, ST3, ST4, ST5, ST6, ST0), __DB>>
               <(T1, T2, T3, T4, T5, T6, T7, T0) as diesel::deserialize::FromStaticSqlRow<(ST1, ST2, ST3, ST4, ST5, ST6, ST7, ST0), __DB>>
             and 24 others
note: required for `models::user::UserModel` to implement `diesel::Queryable<(diesel::sql_types::Uuid, diesel::sql_types::Timestamp, diesel::sql_types::Timestamp, diesel::sql_types::Text), diesel::pg::Pg>`
    --> src/models/user.rs:8:46
     |
8    | #[derive(Debug, GraphQLObject, Identifiable, Queryable, AsChangeset, Clone)]
     |                                              ^^^^^^^^^ unsatisfied trait bound introduced in this `derive` macro
...
11   | pub struct UserModel {
     |            ^^^^^^^^^
     = note: required for `models::user::UserModel` to implement `diesel::deserialize::FromSqlRow<(diesel::sql_types::Uuid, diesel::sql_types::Timestamp, diesel::sql_types::Timestamp, diesel::sql_types::Text), diesel::pg::Pg>`
     = note: required for `(diesel::sql_types::Uuid, diesel::sql_types::Timestamp, diesel::sql_types::Timestamp, diesel::sql_types::Text)` to implement `diesel::query_dsl::load_dsl::private::CompatibleType<models::user::UserModel, diesel::pg::Pg>`
     = note: required for `SelectStatement<FromClause<table>, DefaultSelectClause<...>, ..., ..., ..., ...>` to implement `diesel::query_dsl::LoadQuery<'_, diesel::PgConnection, models::user::UserModel>`
     = note: the full type name has been written to '/Users/soroosh/Repos/rust-gql-boilerplate/target/debug/deps/lib-5c9e4d519f3c4369.long-type-12662555877518073690.txt'
note: required by a bound in `diesel::RunQueryDsl::get_result`

dependencies

chrono = { version = "0.4.31", features = ["serde"] }
uuid = { version = "0.8", features = ["serde", "v4"] }
diesel = { version = "2.1.3", features = [
    "postgres",
    "r2d2",
    "chrono",
    "uuid",
    "serde_json",
] }

The error message indicates that the FromSqlRow trait of Diesel is not being implemented. However, attempts to include it in the derive and remove the conflicting Queryable derivation have resulted in another set of similar errors during compilation. Despite a thorough review of Diesel's documentation, it remains unclear as to what is happening or how to resolve this issue, as the standard documentation simply advises to "derive it". Even a search on Google has not generated any useful insights.

Answer 1

I wanted to share a solution I found for an issue I was facing, and I would like to thank kmdreko for their help.

To fix the issue, I ran the command cargo tree -i uuid --depth=1, which helped me identify two versions of uuid in my dependencies as shown below:

[email protected]
[email protected]

Further, I ran the command cargo tree -i [email protected] --depth=1 and discovered that diesel had added [email protected] to my dependencies:

uuid v1.5.0
└── diesel v2.1.3

Finally, I ran the following command to fix the issue:

cargo update -p "uuid:1.5.0" --precise=0.8.2

I hope this helps anyone facing a similar issue.