Diesel: the trait `diesel::query_builder::QueryFragment<DB>` is not implemented for `u32`

This is probably a simple error, but there aren't really any docs about how Insertable works, and the compiler error is not helpful.

use super::schema::files;

#[derive(Debug, Queryable)]
pub struct File {
    pub id: i64,
    pub file: String,
    pub last_sync: Option<i64>,
    pub size: i64,
    pub attributes: u32,
}

#[derive(Debug, Insertable)]
#[table_name="files"]
pub struct NewFile<'a> {
    pub file: &'a str,
    pub size: i64,
    pub attributes: u32,
}

Gives:

error[E0277]: the trait bound `i64: diesel::Expression` is not satisfied
  --> src\cache\models.rs:15:1
   |
15 | #[derive(Debug, Insertable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `i64`
   |
   = note: required because of the requirements on the impl of `diesel::Expression` for `&'insert i64`
   = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::types::Integer>` for `&'insert i64`
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `u32: diesel::Expression` is not satisfied
  --> src\cache\models.rs:15:1
   |
15 | #[derive(Debug, Insertable)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `diesel::Expression` is not implemented for `u32`
   |
   = note: required because of the requirements on the impl of `diesel::Expression` for `&'insert u32`
   = note: required because of the requirements on the impl of `diesel::expression::AsExpression<diesel::types::Integer>` for `&'insert u32`
   = note: this error originates in a macro outside of the current crate

error[E0277]: the trait bound `i64: diesel::Expression` is not satisfied
  --> src\cache\models.rs:15:1

... etc

This error suggests that you can't insert integers? I can't imagine that is true, though the tests don't have any integers that aren't ids.