diesel-rs/diesel

A safe, extensible ORM and Query Builder for Rust – For feature requests and longer questions also see https://github.com/diesel-rs/diesel/discussions/categories/q-a

Ibraheem Ahmed

@ibraheemdev

Is this query possible with the dsl? select sum(t.total) from (select rate * time_spent as total from tasks) as t

1 reply

Ashwani44

@Ashwani44

Does anybody has any idea about this error:

^^^^^^^^^^^^^^^^ `std::result::Result<_, diesel::result::Error>` cannot be formatted with the default formatter

here is my code:

 let total_department = department.count().get_result(&connection);
    println!("{}", total_department);

Shao Chenyang

@tzsword

@Ashwani44 try this:

let total_department: i64 = department
    .count()
    .get_result(&conn)
    .expect("Error counting cute kittens");
println!("{}", total_department);

Francis Le Roy

@GrandChaman_gitlab

Hi ! I've got a problem applying pending migration from the executable directly. The first time the migration are applied, everything is fine and the table __diesel_schema_migrations is created in the public schema.

All my table are in a separate schema, when I retry to apply the migration, it fails and creates a new table __diesel_schema_migrations in the new schema.

I am not using -csearch_path in the connection string.

How could I force diesel to use the public schema for its __diesel_schema_migrations table ?

2 replies

Jari Pennanen

@Ciantic

Why can't I use chrono's DateTime<Utc> with Sqlite datetime? Conceptually the conversion should not differ from NaiveDateTime. It just seems like Diesel really wants me to use NaiveDateTime even though the datetimes in the database are in UTC.

1 reply

Now I wonder can I do ToSql and FromSql traits myself for the Timestamp <-> DateTime<Utc>

1 reply

Andrew Wheeler(Genusis)

@genusistimelord

is there a way to update a index of an Array?
cstats -> Array<SmallInt>, like i want to filter ID 2 and update it to 12 for example.

Andrew Wheeler(Genusis)

@genusistimelord

I managed to get it to work via sql_query but i was wondering if there is another way?

Georg Semmler

@weiznich

@genusistimelord That's nothing that is currently supported by the built-in dsl, but it should be easily possible to define such operators via diesel_infix_operator! (and/or _postfix/_prefix).
For that specific case we would likely also accept a PR adding those operators to our dsl. See this (diesel-rs/diesel#2566) PR for an example PR.

David Harrington

@harringtondavid_twitter

Error -- sslmode value "require" invalid when SSL support is not compiled in". Connecting to postgres 12 on google cloud. Any suggestions?

James Kerr

@disconsented

Hey @weiznich sorry to bother you, but I am working on tests for PR #1846. Looking around the rest of the tests inside the workspace they seem focused (for lack of a better term). Do you have any objections with me breaking the mould and setting up an in memory sqlite database to run tests against?

Georg Semmler

@weiznich

@harringtondavid_twitter Diesel accepts a valid libpq connection url. See their (Section 33.1.1) for details. I would guess that there is somewhere an example in the google cloud documentation how to connect via libpq.

@disconsented As already mentioned there: I think a much better solution would be to make the ALL_MIGRATIONS constant part of the public API and move such a functionality to diesel_migrations itself.

Erlend Langseth

@Ploppz

why can I not select non-aggregate and aggregate columns in the same select?

^^^^ the trait `NonAggregate` is not implemented for `aggregate_ordering::max::max<diesel::sql_types::Integer, step_idx>`

Full query:

            m::measurement
                .inner_join(p::plate.on(m::plate_id.eq(p::id)))
                .inner_join(e::experiment.on(e::id.eq(p::experiment_id)))
                .inner_join(pr::project.on(pr::id.eq(e::project_id)))
                .inner_join(pj::pipeline_job.on(pj::measurement_id.eq(m::id)))
                .inner_join(wj::worker_job.on(wj::id.eq(pj::job_id)))
                .filter(wj::status.eq("Done"))
                .select((
                    pr::default_pipeline_id,
                    e::default_pipeline_id,
                    p::default_pipeline_id,
                    max(pj::step_idx)
                ))
                .load::<(Option<i64>, Option<i64>, Option<i64>, i32)>(&conn)

Georg Semmler

@weiznich

That's just something that is not supported on 1.4.5 yet.

Erlend Langseth

@Ploppz

When will it be supported? And any ideas how I might get around this for now?

Georg Semmler

@weiznich

Also I think that query misses a group by cause to do what you expect.

Erlend Langseth

@Ploppz

hmm yeah you're right, need to group by m::id

Georg Semmler

@weiznich

About "When will something be supported": We generally do not give any estimates when specific features are implemented.

(Group by is the next thing that is not supported yet on any release, which is also the underlying reason why mixing aggregate and non aggregate clauses is not supported yet)

Erlend Langseth

@Ploppz

Ah, ok

Georg Semmler

@weiznich

Corresponding issues: diesel-rs/diesel#210 and #3

Erlend Langseth

@Ploppz

Thanks.
Is it within the scope of Diesel to support https://www.postgresqltutorial.com/postgresql-coalesce/ ?

oh hm, I guess I should use sql_function for this

Christopher Lee

@Clee681

Hello, I could use a little assistance resolving this compiler error:

5 | #[derive(Insertable)]
  |          ^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `std::string::String`

This example (https://github.com/diesel-rs/diesel/blob/master/examples/postgres/all_about_inserts/src/lib.rs) does not seem to implement anything special for the use of String

Georg Semmler

@weiznich

@Clee681 That's hard to answer without knowing your code. In general this indicates that you've some type mismatch between your schema and your strict.

Christopher Lee

@Clee681

Ah, you're right. There was a type mismatch

#[derive(Insertable)]
#[table_name = "order_items"]
pub struct NewOrderItem {
  pub order_num: i32,
  pub ts: chrono::NaiveDateTime,
  pub description: String,
  pub src_doc: String,
}

table! {
  order_items (id) {
      id -> Int4,
      order_num -> Int4,
      ts -> Timestamp,
      description -> Text,
      src_doc -> Jsonb,
  }
}

src_doc being different caused the compiler error

If I remove the src_doc field, I just get an error for the Expression is not implemented for NaiveDateTime

Is there any documentation or an example for how to implement that expression trait for chrono::NaiveDateTime and Jsonb?

Christopher Lee

@Clee681

I found this for jsonb https://vasilakisfil.social/blog/2020/05/09/rust-diesel-jsonb/

Re: the NaiveDateTime, diesel has a chrono feature :raised_hands:

Christopher Lee

@Clee681

And looks like there's also a serde_json feature :raised_hands: http://docs.diesel.rs/diesel/pg/types/sql_types/struct.Jsonb.html

Pavan Kumar Sunkara

@pksunkara

So, I found the root cause for default not being already implemented. It looks like sqlite doesn't support it.

But Insertable code already compensates for it. So, all I have to do is implement what you suggested and then expression later on

David Harrington

@harringtondavid_twitter

@harringtondavid_twitter Diesel accepts a valid libpq connection url. See their (Section 33.1.1) for details. I would guess that there is somewhere an example in the google cloud documentation how to connect via libpq.

Thanks @weiznich. Is Diesel configured to support these file locations and/or the environment variables for SSL certificates?

https://www.postgresql.org/docs/9.4/libpq-ssl.html
"location of the certificate and key files can be overridden by the connection parameters sslcert and sslkey or the environment variables PGSSLCERT and PGSSLKEY"

https://www.howtoforge.com/postgresql-ssl-certificates
"On the client, we need three files. For Windows, these files must be in %appdata%\postgresql\ directory. For Linux ~/.postgresql/ directory.
root.crt (trusted root certificate)
postgresql.crt (client certificate)
postgresql.key (private key)"

Georg Semmler

@weiznich

@harringtondavid_twitter We just pass the connection string to libpq, so we do whatever libpq does internally.

Erlend Langseth

@Ploppz

I have a problem adding a filter to a working diesel query, which makes it not compile anymore. The relevant filter, query and error: https://bpa.st/WFEA
In short, I have a filter that is dyn BoxableExpression<pipeline::table, Pg, SqlType = diesel::sql_types::Bool> which I think would work if used on the pipeline table alone, but I guess it doesn't work now due to left joins, but why and how can I fix?

Georg Semmler

@weiznich

By using the correct query source for your BoxableExpression. So instead of pipeline::table you need to use the type representing the join.

Erlend Langseth

@Ploppz

How can I do that? The QS type parameter I guess corresponds to QuerySource which says that there are internal structs which represent joins

Georg Semmler

@weiznich

@Ploppz I'm not sure if we already expose the necessary helper types via diesel::dsl. If not I'm happy to receive a PR adding those types.

Erlend Langseth

@Ploppz

So (before I look into it) these types actually exist but are not exposed? There can't possible be one type for each combination of tables you want to join so how does it work?

Georg Semmler

@weiznich

Those types definitively exist, but I'm not sure if they are exposed as part of the public API.

I'm not sure what you want to know with your second question.

Erlend Langseth

@Ploppz

Any hint where I can find that type?

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