Making a type Queryable and Insertable in diesel 0.10

[jimmycuadra]

ruma-identifiers has some code to make a few custom types Insertable and Queryable. This previously worked in diesel 0.9: https://github.com/ruma/ruma-identifiers/blob/29f76ca95d295bca36ec53cd8da72217c5aa0f75/src/lib.rs#L689

This is being used in structs like this:

#[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
#[table_name = "profiles"]
pub struct Profile {
    pub id: ruma_identifiers::UserId,
    pub avatar_url: Option<String>,
    pub displayname: Option<String>,
}

In diesel 0.10, this now results in compiler errors:

error[E0277]: the trait bound `ruma_identifiers::UserId: diesel::Expression` is not satisfied
  --> src/models/profile.rs:18:1
   |
18 | #[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `ruma_identifiers::UserId`
   |
   = note: required because of the requirements on the impl of `diesel::Expression` for `&'insert ruma_identifiers::UserId`
   = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::types::Nullable<diesel::types::Text>>` for `&'insert ruma_identifiers::UserId`
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `ruma_identifiers::UserId: diesel::Expression` is not satisfied
  --> src/models/profile.rs:18:1
   |
18 | #[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `ruma_identifiers::UserId`
   |
   = note: required because of the requirements on the impl of `diesel::Expression` for `&'insert ruma_identifiers::UserId`
   = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::types::Nullable<diesel::types::Text>>` for `&'insert ruma_identifiers::UserId`
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `ruma_identifiers::UserId: diesel::Expression` is not satisfied
  --> src/models/profile.rs:18:1
   |
18 | #[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `ruma_identifiers::UserId`
   |
   = note: required because of the requirements on the impl of `diesel::Expression` for `&'insert ruma_identifiers::UserId`
   = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::types::Nullable<diesel::types::Text>>` for `&'insert ruma_identifiers::UserId`
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `&'insert models::profile::Profile: diesel::Insertable<schema::profiles::table, DB>` is not satisfied
  --> src/models/profile.rs:18:1
   |
18 | #[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::Insertable<schema::profiles::table, DB>` is not implemented for `&'insert models::profile::Profile`
   |
   = help: the following implementations were found:
             <&'insert models::profile::Profile as diesel::Insertable<schema::profiles::table, DB>>
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `ruma_identifiers::UserId: diesel::Expression` is not satisfied
  --> src/models/profile.rs:18:1
   |
18 | #[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `ruma_identifiers::UserId`
   |
   = note: required because of the requirements on the impl of `diesel::Expression` for `&'insert ruma_identifiers::UserId`
   = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::types::Nullable<diesel::types::Text>>` for `&'insert ruma_identifiers::UserId`
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `DB: diesel::backend::SupportsDefaultKeyword` is not satisfied
  --> src/models/profile.rs:18:1
   |
18 | #[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::backend::SupportsDefaultKeyword` is not implemented for `DB`
   |
   = help: consider adding a `where DB: diesel::backend::SupportsDefaultKeyword` bound
   = note: required because of the requirements on the impl of `diesel::insertable::InsertValues<DB>` for `(diesel::insertable::ColumnInsertValue<schema::profiles::columns::id, &'insert ruma_identifiers::UserId>, diesel::insertable::ColumnInsertValue<schema::profiles::columns::avatar_url, diesel::expression::bound::Bound<diesel::types::Nullable<diesel::types::Text>, &std::option::Option<std::string::String>>>, diesel::insertable::ColumnInsertValue<schema::profiles::columns::displayname, diesel::expression::bound::Bound<diesel::types::Nullable<diesel::types::Text>, &std::option::Option<std::string::String>>>)`
   = note: required by `diesel::insertable::InsertValues`
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `ruma_identifiers::UserId: diesel::query_builder::QueryFragment<DB>` is not satisfied
  --> src/models/profile.rs:18:1
   |
18 | #[derive(AsChangeset, Debug, Clone, Identifiable, Insertable, Queryable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::query_builder::QueryFragment<DB>` is not implemented for `ruma_identifiers::UserId`
   |
   = note: required because of the requirements on the impl of `diesel::query_builder::QueryFragment<DB>` for `&'insert ruma_identifiers::UserId`
   = note: required because of the requirements on the impl of `diesel::insertable::InsertValues<DB>` for `(diesel::insertable::ColumnInsertValue<schema::profiles::columns::id, &'insert ruma_identifiers::UserId>, diesel::insertable::ColumnInsertValue<schema::profiles::columns::avatar_url, diesel::expression::bound::Bound<diesel::types::Nullable<diesel::types::Text>, &std::option::Option<std::string::String>>>, diesel::insertable::ColumnInsertValue<schema::profiles::columns::displayname, diesel::expression::bound::Bound<diesel::types::Nullable<diesel::types::Text>, &std::option::Option<std::string::String>>>)`
   = note: required by `diesel::insertable::InsertValues`
   = note: this error originates in a macro outside of the current crate

I played around with it for a while but wasn't able to figure out what changed and how to account for those changes. Any suggestions?

[sgrif]

According to that error message, you're missing impl<'a> AsExpression<Nullable<Text>> for &'a UserId

[sgrif]

I expanded on this in #429 (comment). Feel free to comment here, open a new issue, or ping in gitter if this hasn't been sufficiently answered.