Nullable Timestamptz unsupported with now

[lancecarlson]

Setup

Versions

• Rust:
  nightly
• Diesel:
  0.14.1
• Database:
  postgres
• Operating System
  Fedora

Feature Flags

• diesel:
• diesel_codegen:

Problem Description

I was attempting to write a query that updated a timestamp column that was nullable and received a compile error. Example query:

diesel::update(import_jobs.filter(completed_at.is_null()))
        .set(completed_at.eq(diesel::expression::dsl::now))
        .execute(conn)?;

What are you trying to accomplish?

^^^

What is the expected output?

Successful compile

What is the actual output?

error[E0271]: type mismatch resolving `<diesel::expression::nullable::Nullable<diesel::expression::now> as diesel::Expression>::SqlType == diesel::types::Nullable<diesel::types::Timestamptz>` --> src/importer.rs:52:25 | 52 | .set((failed_at.eq(diesel::expression::dsl::now.nullable()), failed_reason.eq("aborted"))) | ^^ expected struct `diesel::types::Timestamp`, found struct `diesel::types::Timestamptz` | = note: expected type `diesel::types::Nullable<diesel::types::Timestamp>` found type `diesel::types::Nullable<diesel::types::Timestamptz>`

Current work around

@sgrif Recommended this for now:

let nullable_timestamptz = AsExpression::<Timestamptz>::as_expression(diesel::expression::dsl::now).nullable();

diesel::update(import_jobs.filter(completed_at.is_null()))
        .set(completed_at.eq(nullable_timestamptz))
        .execute(conn)?;