gaxxx / rust-crud

using rust for crud

How to build a rust service using actix & postgresql

prequesition

• postgresql
• rust

Setup environment

• clion
• postgrsql: grant a member, generate connection string
• rust:
  • using stable channel
  • install disel

Initial

• create a dummy projects

Add json support

• add serde

setup diesel

add to cargo.toml

diesel = { version = "1.0.0", features = ["postgres"] }
dotenv = "0.9.0"
r2d2-diesel = "1.0.0"

cargo install diesel_cli --no-default-features --features postgres

add db support

add line to hda_file if needed

host    all             all             127.0.0.1/32            md5

setup a postgresql db

sudo -u postgres psql
ALTER USER postgres PASSWORD 'password';
create database heroes;

the connection string would be "postgres://postgres:password@127.0.0.1/heroes"

echo DATABASE_URL=postgres://postgres:password@127.0.0.1/heroes > .env
disel setup 
// generage module tables
diesel migration generate heroes

setup users model & table update up.sql

create table users (
id serial primary key,
name varchar not null  default '',
identity varchar not null default '',
hometown varchar not null default '',
age int not null default 0
);

diesel migration run
diesel migration redo

update crud

// create 
diesel::insert_into(schema::users::table)
        .values(hero.into_inner())
// read
users.filter(id.eq(update_id.into_inner()))
        .first::<hero::Hero>(&*db.get());
// update
diesel::update(users.filter(id.eq(update_id.into_inner())))
        .set(hero.into_inner())
// delete
diesel::delete(users.filter(id.eq(update_id.into_inner())))


//list
users.load::<hero::Hero>(&*db.get()).unwrap();

pagination

make query pagable

impl<T> QueryFragment<Pg> for Paginated<T>
    where
        T: QueryFragment<Pg>,
{
    fn walk_ast(&self, mut out: AstPass<Pg>) -> QueryResult<()> {
        out.push_sql("SELECT *, COUNT(*) OVER () FROM (");
        self.query.walk_ast(out.reborrow())?;
        out.push_sql(") t LIMIT ");
        out.push_bind_param::<BigInt, _>(&self.count)?;
        out.push_sql(" OFFSET ");
        let offset = self.start;
        out.push_bind_param::<BigInt, _>(&offset)?;
        Ok(())
    }
}

how to use

let query = users.order(id.asc());
let query = query.paginate(req.start.unwrap_or(0).into());
let all_users : Vec<_> = query.load::<(hero::Hero, i64)>(&*db.get()).unwrap();
web::Json(all_users.iter().map(|v| v.0.clone()).collect::<Vec<_>>())