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use std::collections::HashMap;
use std::marker::PhantomData;
use cqrs_es::{Aggregate, AggregateContext, AggregateError, EventEnvelope, EventStore};
use postgres::Connection;
pub struct PostgresStore<A: Aggregate>
{
conn: Connection,
_phantom: PhantomData<A>,
}
impl<A: Aggregate> PostgresStore<A>
{
pub fn new(conn: Connection) -> Self {
PostgresStore {
conn,
_phantom: PhantomData,
}
}
}
static INSERT_EVENT: &str = "INSERT INTO events (aggregate_type, aggregate_id, sequence, payload, metadata)
VALUES ($1, $2, $3, $4, $5)";
static SELECT_EVENTS: &str = "SELECT aggregate_type, aggregate_id, sequence, payload, metadata
FROM events
WHERE aggregate_type = $1 AND aggregate_id = $2 ORDER BY sequence";
impl<A: Aggregate> EventStore<A, PostgresStoreAggregateContext<A>> for PostgresStore<A>
{
fn load(&self, aggregate_id: &str) -> Vec<EventEnvelope<A>> {
let agg_type = A::aggregate_type();
let id = aggregate_id.to_string();
let mut result = Vec::new();
match self.conn.query(SELECT_EVENTS, &[&agg_type, &id]) {
Ok(rows) => {
for row in rows.iter() {
let aggregate_type: String = row.get("aggregate_type");
let aggregate_id: String = row.get("aggregate_id");
let s: i64 = row.get("sequence");
let sequence = s as usize;
let payload: A::Event = match serde_json::from_value(row.get("payload")) {
Ok(payload) => payload,
Err(err) => {
panic!("bad payload found in events table for aggregate id {} with error: {}", &id, err);
}
};
let event = EventEnvelope::new(aggregate_id, sequence, aggregate_type, payload);
result.push(event);
}
}
Err(e) => { println!("{:?}", e); }
}
result
}
fn load_aggregate(&self, aggregate_id: &str) -> PostgresStoreAggregateContext<A> {
let committed_events = self.load(aggregate_id);
let mut aggregate = A::default();
let mut current_sequence = 0;
for envelope in committed_events {
current_sequence = envelope.sequence;
let event = envelope.payload;
aggregate.apply(&event);
};
PostgresStoreAggregateContext {
aggregate_id: aggregate_id.to_string(),
aggregate,
current_sequence,
}
}
fn commit(&self, events: Vec<A::Event>, context: PostgresStoreAggregateContext<A>, metadata: HashMap<String, String>) -> Result<Vec<EventEnvelope<A>>, AggregateError> {
let aggregate_id = context.aggregate_id.as_str();
let current_sequence = context.current_sequence;
let wrapped_events = self.wrap_events(aggregate_id, current_sequence, events, metadata);
let trans = match self.conn.transaction() {
Ok(t) => { t }
Err(err) => {
return Err(AggregateError::TechnicalError(err.to_string()));
}
};
for event in &wrapped_events {
let agg_type = event.aggregate_type.clone();
let id = context.aggregate_id.clone();
let sequence = event.sequence as i64;
let payload = match serde_json::to_value(&event.payload) {
Ok(payload) => payload,
Err(err) => {
panic!("bad payload found in events table for aggregate id {} with error: {}", &id, err);
}
};
let metadata = match serde_json::to_value(&event.metadata) {
Ok(metadata) => metadata,
Err(err) => {
panic!("bad metadata found in events table for aggregate id {} with error: {}", &id, err);
}
};
match self.conn.execute(INSERT_EVENT, &[&agg_type, &id, &sequence, &payload, &metadata]) {
Ok(_) => {}
Err(err) => {
match err.code() {
None => {}
Some(state) => {
if state.code() == "23505" {
return Err(AggregateError::TechnicalError("optimistic lock error".to_string()));
}
}
}
panic!("unable to insert event table for aggregate id {} with error: {}\n and payload: {}", &id, err, &payload);
}
};
}
match trans.commit() {
Ok(_) => Ok(wrapped_events),
Err(err) => Err(AggregateError::TechnicalError(err.to_string())),
}
}
}
pub struct PostgresStoreAggregateContext<A: Aggregate>
{
pub aggregate_id: String,
pub aggregate: A,
pub current_sequence: usize,
}
impl<A: Aggregate> AggregateContext<A> for PostgresStoreAggregateContext<A>
{
fn aggregate(&self) -> &A {
&self.aggregate
}
}