the trait bound NaiveDateTime: FromSql<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg> is not satisfied

[tuanhuu162]

Setup

Versions

• Rust: rustc 1.51.0 (2fd73fabe 2021-03-23)
• Diesel: 1.4.6
• Database: postgresql
• Operating System: Unbuntu 18.04

Feature Flags

• diesel:

Problem Description

I am trying to write a module that can query and insert into tables in PostgreSQL. But when I use a nullable timestamp field, the compiler panic with an error:

error[E0277]: the trait bound `NaiveDateTime: FromSql<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` is not satisfied
  --> src/database/user.rs:66:18
   |
66 |                 .get_result(&connection.get().unwrap())?;
   |                  ^^^^^^^^^^ the trait `FromSql<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` is not implemented for `NaiveDateTime`
   |
   = help: the following implementations were found:
             <NaiveDateTime as FromSql<diesel::sql_types::Timestamp, Pg>>
             <NaiveDateTime as FromSql<diesel::sql_types::Timestamptz, Pg>>
   = note: required because of the requirements on the impl of `Queryable<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` for `NaiveDateTime`
   = note: 2 redundant requirements hidden
   = note: required because of the requirements on the impl of `Queryable<(diesel::sql_types::Integer, diesel::sql_types::Uuid, diesel::sql_types::Text, diesel::sql_types::Text, diesel::sql_types::Text, diesel::sql_types::Nullable<diesel::sql_types::Timestamp>), Pg>` for `User`
   = note: required because of the requirements on the impl of `LoadQuery<PooledConnection<ConnectionManager<PgConnection>>, User>` for `InsertStatement<users::table, ValuesClause<(ColumnInsertValue<users::columns::email, diesel::expression::bound::Bound<diesel::sql_types::Text, std::string::String>>, ColumnInsertValue<users::columns::name, diesel::expression::bound::Bound<diesel::sql_types::Text, std::string::String>>, ColumnInsertValue<users::columns::hash, diesel::expression::bound::Bound<diesel::sql_types::Text, std::string::String>>), users::table>>`

I think the Nullable should be implemented here.

What are you trying to accomplish?

A lacked feature when using diesel.

What is the expected output?

That it should compile (or show me some other errors).

What is the actual output?

warning: unused manifest key: dependencies.serde.feature
   Compiling todolist v0.1.0 (/home/ubuntu/work/rust_space/todolist)
warning: unused import: `error::BlockingError`
 --> src/api/user_handle.rs:1:17
  |
1 | use actix_web::{error::BlockingError, web, HttpResponse, Responder};
  |                 ^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused import: `crate::errors::ToDoError`
 --> src/api/user_handle.rs:7:5
  |
7 | use crate::errors::ToDoError;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^

warning: unused import: `Queryable`
 --> src/database/user.rs:7:23
  |
7 | use diesel::prelude::{Queryable, Insertable};
  |                       ^^^^^^^^^

error[E0277]: the trait bound `NaiveDateTime: FromSql<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` is not satisfied
  --> src/database/user.rs:66:18
   |
66 |                 .get_result(&connection.get().unwrap())?;
   |                  ^^^^^^^^^^ the trait `FromSql<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` is not implemented for `NaiveDateTime`
   |
   = help: the following implementations were found:
             <NaiveDateTime as FromSql<diesel::sql_types::Timestamp, Pg>>
             <NaiveDateTime as FromSql<diesel::sql_types::Timestamptz, Pg>>
   = note: required because of the requirements on the impl of `Queryable<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` for `NaiveDateTime`
   = note: 2 redundant requirements hidden
   = note: required because of the requirements on the impl of `Queryable<(diesel::sql_types::Integer, diesel::sql_types::Uuid, diesel::sql_types::Text, diesel::sql_types::Text, diesel::sql_types::Text, diesel::sql_types::Nullable<diesel::sql_types::Timestamp>), Pg>` for `User`
   = note: required because of the requirements on the impl of `LoadQuery<PooledConnection<ConnectionManager<PgConnection>>, User>` for `InsertStatement<users::table, ValuesClause<(ColumnInsertValue<users::columns::email, diesel::expression::bound::Bound<diesel::sql_types::Text, std::string::String>>, ColumnInsertValue<users::columns::name, diesel::expression::bound::Bound<diesel::sql_types::Text, std::string::String>>, ColumnInsertValue<users::columns::hash, diesel::expression::bound::Bound<diesel::sql_types::Text, std::string::String>>), users::table>>`

error[E0277]: the trait bound `NaiveDateTime: FromSql<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` is not satisfied
  --> src/database/user.rs:88:18
   |
88 |                 .load::<User>(&connection.get().unwrap())?;
   |                  ^^^^ the trait `FromSql<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` is not implemented for `NaiveDateTime`
   |
   = help: the following implementations were found:
             <NaiveDateTime as FromSql<diesel::sql_types::Timestamp, Pg>>
             <NaiveDateTime as FromSql<diesel::sql_types::Timestamptz, Pg>>
   = note: required because of the requirements on the impl of `Queryable<diesel::sql_types::Nullable<diesel::sql_types::Timestamp>, Pg>` for `NaiveDateTime`
   = note: 2 redundant requirements hidden
   = note: required because of the requirements on the impl of `Queryable<(diesel::sql_types::Integer, diesel::sql_types::Uuid, diesel::sql_types::Text, diesel::sql_types::Text, diesel::sql_types::Text, diesel::sql_types::Nullable<diesel::sql_types::Timestamp>), Pg>` for `User`
   = note: required because of the requirements on the impl of `LoadQuery<_, User>` for `diesel::query_builder::SelectStatement<users::table, query_builder::select_clause::DefaultSelectClause, query_builder::distinct_clause::NoDistinctClause, query_builder::where_clause::WhereClause<diesel::expression::operators::Eq<users::columns::email, diesel::expression::bound::Bound<diesel::sql_types::Text, &std::string::String>>>>`

warning: unused import: `Insertable`
 --> src/database/user.rs:7:34
  |
7 | use diesel::prelude::{Queryable, Insertable};
  |                                  ^^^^^^^^^^

error: aborting due to 2 previous errors; 4 warnings emitted

For more information about this error, try `rustc --explain E0277`.
error: could not compile `todolist`

To learn more, run the command again with --verbose.

Are you seeing any additional errors?

No

Steps to reproduce

Run cargo run on my code base
I have the following lines in my src/lib.rs file in this order:

extern crate diesel;
// ...
use diesel::prelude::*;
// ...
mod schema;
mod models;

The diesel-generated src/schema.rs file looks like this:

table! {
    users (user_id) {
        user_id -> Int4,
        user_uuid -> Uuid,
        name -> Varchar,
        email -> Varchar,
        hash -> Varchar,
        created_at -> Nullable<Timestamp>,
    }
}

And the src/models.rs file looks like this:

#[derive(Debug, Deserialize, Serialize, Queryable, Insertable)]
#[table_name = "users"]
pub struct User {
    #[serde(skip)]
    pub user_id: i32,
    #[serde(skip)]
    pub user_uuid: Uuid,
    pub email: String,
    pub name: String,
    #[serde(skip)]
    pub hash: String,
    pub created_at: NaiveDateTime
}

Checklist

• I have already looked over the issue tracker and the disussion forum for similar possible closed issues.

• This issue can be reproduced on Rust's stable channel. (Your issue will be
  closed if this is not the case)
• This issue can be reproduced without requiring a third party crate

[weiznich]

Closed duplicate of #2011 and #2434 and any other issue with an similar error message. See the documentation of the Nullable SQL type for compatible rust types.

[sulaman0]

Hi @tuanhuu162 use this line in model.rs
pub created_at: Option<NaiveDateTime>