diesel-autoincrement-new-struct

Stop copying and pasting structs with the id field removed just so you can insert objects into tables with autoincrementing primary keys.

Motivation

I mean really, who wants to do all that copying and pasting? Who wants to keep attributes and documentation in sync between two otherwise identical structs?

Examples

First, the ugly example, in which you wrap your whole struct definition in a macro:

```rust use dieselautoincrementnewstruct::dieselnew; use diesel::prelude::*;

table! { users(id) { id -> Integer, name -> Text, } }

dieselnew! { #[derive(Debug, Clone, Queryable, AsChangeset)] #[diesel(tablename = users)] /// This is a user pub struct User { /// This is the ID of the user id: i32, /// This is the name of the user name: String } }

// The code below gets generated by diesel_new!

[derive(Debug, Clone, Queryable, AsChangeset)]

[derive(Insertable)]

[diesel(table_name = users)]

/// This is a user pub struct NewUser { /// This is the name of the user name: String } ```

Pretty neat, right? But we can do better. Check this out.

```rust

[macro_use]

extern crate macrorulesattribute;

use diesel::prelude::*;

attributealias! { #[apply(New!)] = #[macrorulesderive(dieselautoincrementnewstruct::diesel_new)]; }

table! { users(id) { id -> Integer, name -> Text, } }

[apply(New!)]

[derive(Debug, Clone, Queryable, AsChangeset)]

[diesel(table_name = users)]

/// This is a user pub struct User { /// This is the ID of the user id: i32, /// This is the name of the user name: String }

// The code below gets generated by #[apply(New!)]

[derive(Debug, Clone, Queryable, AsChangeset)]

[derive(Insertable)]

[diesel(table_name = users)]

/// This is a user pub struct NewUser { /// This is the name of the user name: String } ```

Much better, ne?

This whole idea came about after finding the excellent macro_rules_attribute crate by Daniel Henry-Mantilla, aka my personal Rust macro hero.

If you want to use this crate with the #[apply] attribute as in the second example, make sure you add macro_rules_attribute to your Cargo.toml:

toml macro_rules_attribute = "0.1"

And add this at the top of your lib.rs or main.rs file:

```rust

[macro_use]

extern crate macrorulesattribute;

attributealias! { #[apply(New!)] = #[macrorulesderive(dieselautoincrementnewstruct::diesel_new)]; } ```

Then, you can import crate::New in whichever file you want and apply it to your structs with the #[apply] attribute.

Notes

• This crate doesn't re-export Diesel, so make sure you have use diesel::prelude::*; or use diesel::Insertable; in whichever files you use this macro
• This crate requires at least whichever version or revision of Diesel where the #[diesel(table_name = ...)] attribute stopped taking a double quoted string

The #[apply] attribute should always be the topmost attribute above a struct, unless the struct that you want to use it on is also deriving Identifiable. If that is the case, you should have that derive been the topmost attribute above the struct so that it is excluded when generating the NewStruct, becuase obviously, without an id, it won't be Identifiable:

```rust

[derive(Identifiable)]

[apply(New!)]

[derive(Debug, Clone, Queryable, AsChangeset)]

[diesel(table_name = users)]

/// This is a user pub struct User { /// This is the ID of the user id: i32, /// This is the name of the user name: String } ```