New Entity

The NewEntity type represents the data of the Entity in a pre-persisted state. It gets passed to the Repository::create function where the IntoEvents trait emits the initial EntityEvents which are then persisted and used to hydrate the actual Entity.

It is also recommended that any validation of the initial attributes is performed on this type to ensure that the Entity will be in a legal state once it gets hydrated for the first time. Using the derive_builder crate is recommended for this purpose.

#![allow(unused)]
fn main() {
extern crate es_entity;
extern crate sqlx;
extern crate serde;
extern crate derive_builder;
use serde::{Deserialize, Serialize};
use es_entity::*;
use derive_builder::Builder;
es_entity::entity_id! { UserId };
#[derive(EsEvent, Debug, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
#[es_event(id = "UserId")]
pub enum UserEvent {
    Initialized { id: UserId, name: String },
}
const MAX_NAME_LENGTH: usize = 100;

#[derive(Debug, Builder)]
// Specify the `validation` fn
#[builder(build_fn(validate = "Self::validate"))]
pub struct NewUser {
    #[builder(setter(into))]
    pub id: UserId,
    #[builder(setter(into))]
    pub name: String,
}

impl NewUser {
    pub fn builder() -> NewUserBuilder {
        NewUserBuilder::default()
    }
}
impl NewUserBuilder {
    // Execute some validation that ensures the initial `Entity` is legal
    fn validate(&self) -> Result<(), String> {
        if self.name.as_ref().expect("name wasn't set").len() > MAX_NAME_LENGTH {
            return Err("Name length exceeded".to_string());
        }
        Ok(())
    }
}

impl IntoEvents<UserEvent> for NewUser {
    // This `fn` returns the first `Events` of the `Entity`
    fn into_events(self) -> EntityEvents<UserEvent> {
        EntityEvents::init(
            self.id,
            [UserEvent::Initialized {
                id: self.id,
                name: self.name,
            }],
        )
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn user_creation() {
        let new_user = NewUser::builder().id("user-id").name("Steven").build();
        assert!(new_user.is_ok());
    }
}
}