Suggestions to distribute a library crate that uses diesel to manage a database

[Datron]

Hello!

I'm working on a project that has a few library crates linked to a binary crate in the same repository. The library crates use diesel and store data in postgres. I'm able to run the binary crate without any issues, but when I try to import the library crates into another repository they start to throw weird errors that don't show up when I run the binary crate. An example is:

 the trait bound `schema::sql_types::ExperimentStatusType: QueryId` is not satisfied
    --> path/superposition/crates/experimentation_platform/src/api/experiments/helpers.rs:186:15
     |
186  |         .load(conn)?;
     |          ---- ^^^^ the trait `QueryId` is not implemented for `schema::sql_types::ExperimentStatusType`
     |          |
     |          required by a bound introduced by this call
     |
     = help: the following other types implement trait `QueryId`:
               Box<T>
               DeleteStatement<T, U, Ret>
               FromClause<F>
               query_builder::select_clause::DefaultSelectClause<QS>
               BoxedSqlQuery<'_, DB, Query>
               query_builder::where_clause::BoxedWhereClause<'a, DB>
               query_source::joins::Join<Left, Right, Kind>
               diesel::expression::ops::numeric::Add<Lhs, Rhs>
             and 674 others
     = note: required for `diesel::expression::bound::Bound<schema::sql_types::ExperimentStatusType, models::ExperimentStatusType>` to implement `QueryId`
     = note: 8 redundant requirements hidden
     = note: required for `SelectStatement<FromClause<table>, DefaultSelectClause<FromClause<table>>, ..., ...>` to implement `QueryId`
     = note: the full type name has been written to 'path/context-aware-config/target/debug/deps/experimentation_platform-98f3466be937ed14.long-type-6488301493617960843.txt'
     = note: required for `SelectStatement<FromClause<table>, DefaultSelectClause<FromClause<table>>, ..., ...>` to implement `LoadQuery<'_, _, _>`
     = note: the full type name has been written to 'path/context-aware-config/target/debug/deps/experimentation_platform-98f3466be937ed14.long-type-6488301493617960843.txt'
note: required by a bound in `diesel::RunQueryDsl::load`
    --> path/.cargo/registry/src/index.crates.io-6f17d22bba15001f/diesel-2.1.6/src/query_dsl/mod.rs:1542:15
     |
1540 |     fn load<'query, U>(self, conn: &mut Conn) -> QueryResult<Vec<U>>
     |        ---- required by a bound in this associated function
1541 |     where
1542 |         Self: LoadQuery<'query, Conn, U>,
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `RunQueryDsl::load`

For more information about this error, try `rustc --explain E0277`.

I tried implementing QueryId but this error still did not go away.

I'm wondering how I can go about properly exporting the library crates so I don't get this issue.

Also, if there is a way to export the migrations folder too so that a downstream binary crate can run it, please let me know.

[weiznich]

I fear it's not possible to help you based on the provided information. You need to provide a reproducible example for your problem so that someone can else can see what's the problem there. Otherwise you can try to use cargo tree to double check that you only have one version of diesel in your dependency tree.

[Datron]

Hi @weiznich
The repository that contains both library crates and binary crates is here:
https://github.com/juspay/superposition

Here's a reproducible example of my problem. I see the same issue and there is no diesel dependency added yet.
https://github.com/Datron/superposition_example

[weiznich]

I think that might be a bug/breaking change in diesel-derive-enum. At least I can reproduce it with the following commands:

git clone https://github.com/juspay/superposition
cd superposition/crates/experimentation_platform
cargo check # works fine
cargo update -p diesel-derive-enum
cargo check # fails

It seems like they used to generate the QueryId impl for custom sql types for you but stopped doing that with the 2.1 release. You can likely fix that in your code by just adding diesel::query_builder::QueryId to the custom_type_derives as documented here. Diesel usually generates a diesel.toml file that already contains this line for new projects.

[Datron]

@weiznich Ah okay. Let me try this and get back to you.

[Datron]

@weiznich I'm using diesel-derive-enum=2.0.1 for all my crates, yet I still get the error I had mentioned earlier about the trait QueryId not being implemented for the enum ExperimentStatusType. Anything else I can do?

[Datron]

@weiznich you can ignore the above message, the error goes away when I add these dependencies in the crate Cargo.toml file. Earlier, I was adding them to the workspace Cargo.toml file.