diesel::debug_query doesn't show the RETURNING part of query when used with PostgreSQL

[blazern]

Setup

Versions

• Rust: rustc 1.19.0 (0ade33941 2017-07-17)
• Diesel: 0.16.0
• Database: PostgreSQL 9.5.8
• Operating System Ubuntu 16.04

Feature Flags

• diesel: postgres, uuid
• diesel_codegen: postgres

Problem Description

Created an PostgreSQL table and a user, the user was granted only with INSERT privilege.
Used infer_schema to generate wrappers and correct URL to connect to the local DB.
Executed:

    diesel::insert(&my_inserted_value).into(schema::my_table_name::table).get_result(&connection)

which failed with DieselError(DatabaseError(__Unknown, "permission denied for relation my_table_name").

Tried to insert the same value manually by psql - the insertion worked.
Decided to use diesel::debug_query to see what query Diesel used to INSERT.

Executed:

    let query = diesel::insert(&my_inserted_value).into(schema::my_table_name::table);
    let debug = diesel::debug_query::<diesel::pg::Pg, _>(&query);
    println!("The insert query: {:?}", debug);

Which printed out:

The insert query: Query { sql: "INSERT INTO \"my_table_name\" (\"uid\", \"k_uid\") VALUES ($1, $2)", binds: [Uuid("b351f809-3e4c-40cd-bb64-d8c8c07c1086"), 123] }

Tried to execute this very query manually by psql - manual insertion worked, while insertion by Diesel failed.

Opened PostgreSQL logs, and there was the real query which Diesel used:

db_client@db_main STATEMENT:  INSERT INTO "my_table_name" ("uid", "k_uid") VALUES ($1, $2) RETURNING "my_table_name"."id", "my_table_name"."uid", "my_table_name"."k_uid"

The RETURNING clause was the problem - it requires SELECT privilege, but the user I used had only INSERT privilege.

If diesel::debug_query shown the correct query I wouln't have to look it up in the logs.

Checklist

• I have already looked over the issue tracker for similar issues.

[sgrif]

There's not really anything we can do here. debug_query shows the SQL of the query as it exists at that point (as if it were passed to execute). If we tried to mirror the behavior of get_results here, it would cause debug_query to stop working on all backends other than PG. You can append the returning clause yourself by calling .as_query or .returning(table::all_columns)

[blazern]

@sgrif, is there a way to see the full query used by Diesel though?
If one can't see the full query used by Diesel, it can be hard to debug wrong behaviour.

[sgrif]

My last comment described how to see the full query, depending on whether it is run with execute or get_results