Diesel 2.0.0 officially released, Rust ORM framework

Diesel 2.0.0 has been officially released . It is said that the development cycle of this version is as long as 3 years and contains more than 1700 commits.

Diesel is a safe and extensible Rust ORM framework and query builder. Diesel avoids runtime errors and provides the best performance.

2.0 adds many new features and rewrites most of the internals. Since this is a new major version, it also contains many breaking changes, see the migration guide for specific handling .

Update highlights

• fully type-checkedGROUP BY
• Support for table aliases
• Support for defining select clauses by corresponding types
• Support UNION/ INTERSECTInquiry

In addition, Diesel 2.0.0 fixes several issues in the type level SQL representation, which now correctly handles the following cases:

• mixed nesting LEFT JOINSandINNER JOINS
• Chaining mixed nullable expressions via AND, and similar operatorsOR

---

support GROUP BYclause

Diesel 2.0 added GROUP BYsupport for clauses for select queries.

Example

 users::table.inner_join(posts::table)
    .group_by(users::id)
    .select((users::name, count(posts::id)))

Support for table aliases

The following query demonstrates this functionality:

// Define new table alias for the existing `users` table
let users1 = diesel::alias!(schema::users as user1);

// Use the corresponding alias inside any existing query
users::table
    .inner_join(users1.on(users::id).eq(users1.field(users::id))))
    .select((users::id, users::name, users1.field(users::name)))
    .order_by(users1.field(users::id))

Support UNION/ INTERSECTInquiry

This feature easily chains together multiple queries as long as they return fields of the same type.

 users.select(user_name.nullable())
    .union(animals.select(animal_name).filter(animal_name.is_not_null()))

Release Note | Changelog