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//! Retrieves the n most recent documents in a collection.
//!
//! Retrieves the n / skip most recent items from the collection, pushed back by offset,
//! and returns a Vec of the type that the collection is assigned to.
//!
//! If n is greater than the number of documents in the collection, the 0th index of the returned Vec
//! will be the first document in the collection ..
//!
//! # Examples
//!
//! ```
//! use mungos::{Mungos}
//! use serde::{Serialize, Deserialize}
//!
//! #[derive(Debug, Serialize, Deserialize)]
//! struct Item {
//! field: String
//! }
//!
//! let db = Mungos::new("uri", "app name", timeout).await;
//! let collection = db.connection::<Item>("db name", "collection name");
//!
//! let n = 10
//! let skip = 2
//! //returns the n / skip = 5 most recent docs in the collection,
//! //in order of oldest to latest
//! let items = collection.get_most_recent_with_skip(n, skip, 0, None, None).await.unwrap();
//!
//! ```
//!
use futures::stream::TryStreamExt;
use mongodb::{
bson::{doc, Document},
error::Result,
options::FindOptions,
};
use serde::de::DeserializeOwned;
use crate::Collection;
impl<T: DeserializeOwned + Unpin + Send + Sync> Collection<T> {
pub async fn get_most_recent_with_skip(
&self,
num_items: i64,
skip: i64,
offset: u64,
filter: impl Into<Option<Document>>,
projection: impl Into<Option<Document>>,
) -> Result<Vec<T>> {
let find_options = FindOptions::builder()
.sort(doc! { "_id": -1 })
.skip(offset)
.limit(num_items * skip)
.projection(projection)
.build();
let mut cursor = self.collection.find(filter, find_options).await?;
let mut items = Vec::new();
let mut step = 0;
while let Some(item) = cursor.try_next().await? {
if step % skip == 0 {
items.push(item);
}
step += 1;
}
items.reverse();
Ok(items)
}
}