diesel-rs/diesel

SupportsReturningClause mysql

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#2535 opened on Oct 9, 2020

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 (16 comments) (9 reactions) (1 assignee)Rust (12,054 stars) (1,003 forks)batch import
documentationhelp wantedmysql

Description

Problem Description

Following the get started guide step by step I was willing to run insert code with mysql.

        // ...
        let inserted = diesel::insert_into(entities::table)
            .values(&ext)
            .get_result::<Entity>(&conn)
            .unwrap();

But I was constantly getting a compile error.

the trait bound `diesel::mysql::Mysql: diesel::backend::SupportsReturningClause` is not satisfied
required because of the requirements on the impl of `diesel::query_builder::QueryFragment<diesel::mysql::Mysql>` for `diesel::query_builder::returning_clause::ReturningClause<schema::extension::columns::id>`
required because of the requirements on the impl of `diesel::query_builder::QueryFragment<diesel::mysql::Mysql>` for 
...

And eventually (after figuring out that execute doesn't return id :smile: ) I took a look at the doc and it seems to me currently it's impossible to run such code with mysql since its supported only by postgress right?

https://docs.diesel.rs/diesel/backend/trait.SupportsReturningClause.html

What are you trying to accomplish?

If it's true I would consider adding some information somewhere that it's not work with mysql could reduce peoples time spent on trying to resolve it. Probably in get_result doc comment.

Comment

I may be incorrect in my assumptions in which case I am sorry :disappointed:

And thank you for the crate.

Contributor guide

Tech stack
rust
Domain
backenddatabase
Issue type
documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic Rust knowledgefamiliarity with Diesel ORM
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
90
Research direction
The issue requests adding a note in the documentation for the `get result` method, indicating that MySQL does not support the `RETURNING` clause. The fix should be in the Rust source code comments of the `get result` function or in the Diesel documentation. Maintainers may need to discuss the exact location and wording.