329 lines
10 KiB
Rust
329 lines
10 KiB
Rust
use crate::{error::*, DatabaseConnection, SelectorTrait};
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use async_stream::stream;
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use futures::Stream;
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use sea_query::{Alias, Expr, SelectStatement};
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use std::{marker::PhantomData, pin::Pin};
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pub type PinBoxStream<'db, Item> = Pin<Box<dyn Stream<Item = Item> + 'db>>;
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#[derive(Clone, Debug)]
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pub struct Paginator<'db, S>
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where
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S: SelectorTrait + 'db,
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{
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pub(crate) query: SelectStatement,
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pub(crate) page: usize,
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pub(crate) page_size: usize,
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pub(crate) db: &'db DatabaseConnection,
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pub(crate) selector: PhantomData<S>,
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}
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impl<'db, S> Paginator<'db, S>
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where
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S: SelectorTrait + 'db,
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{
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/// Fetch a specific page
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pub async fn fetch_page(&self, page: usize) -> Result<Vec<S::Item>, SeaErr> {
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let query = self
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.query
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.clone()
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.limit(self.page_size as u64)
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.offset((self.page_size * page) as u64)
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.to_owned();
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let builder = self.db.get_query_builder_backend();
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let stmt = builder.build(&query);
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let rows = self.db.query_all(stmt).await?;
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let mut buffer = Vec::with_capacity(rows.len());
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for row in rows.into_iter() {
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// TODO: Error handling
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buffer.push(S::from_raw_query_result(row)?);
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}
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Ok(buffer)
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}
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/// Fetch the current page
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pub async fn fetch(&self) -> Result<Vec<S::Item>, SeaErr> {
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self.fetch_page(self.page).await
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}
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/// Get the total number of pages
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pub async fn num_pages(&self) -> Result<usize, SeaErr> {
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let builder = self.db.get_query_builder_backend();
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let stmt = builder.build(
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SelectStatement::new()
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.expr(Expr::cust("COUNT(*) AS num_rows"))
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.from_subquery(
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self.query.clone().reset_limit().reset_offset().to_owned(),
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Alias::new("sub_query"),
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),
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);
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let result = match self.db.query_one(stmt).await? {
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Some(res) => res,
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None => return Ok(0),
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};
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let num_rows = result.try_get::<i32>("", "num_rows")? as usize;
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let num_pages = (num_rows / self.page_size) + (num_rows % self.page_size > 0) as usize;
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Ok(num_pages)
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}
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/// Increment the page counter
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pub fn next(&mut self) {
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self.page += 1;
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}
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/// Get current page number
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pub fn cur_page(&self) -> usize {
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self.page
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}
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/// Fetch one page and increment the page counter
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pub async fn fetch_and_next(&mut self) -> Result<Option<Vec<S::Item>>, SeaErr> {
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let vec = self.fetch().await?;
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self.next();
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let opt = if !vec.is_empty() { Some(vec) } else { None };
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Ok(opt)
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}
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/// Convert self into an async stream
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pub fn into_stream(mut self) -> PinBoxStream<'db, Result<Vec<S::Item>, SeaErr>> {
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Box::pin(stream! {
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loop {
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if let Some(vec) = self.fetch_and_next().await? {
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yield Ok(vec);
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} else {
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break
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}
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}
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})
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}
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}
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#[cfg(test)]
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#[cfg(feature = "mock")]
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mod tests {
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use crate::entity::prelude::*;
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use crate::tests_cfg::*;
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use crate::{DatabaseConnection, MockDatabase, Transaction};
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use futures::TryStreamExt;
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use sea_query::{Alias, Expr, SelectStatement, Value};
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fn setup() -> (DatabaseConnection, Vec<Vec<fruit::Model>>) {
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let page1 = vec![
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fruit::Model {
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id: 1,
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name: "Blueberry".into(),
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cake_id: Some(1),
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},
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fruit::Model {
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id: 2,
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name: "Rasberry".into(),
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cake_id: Some(1),
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},
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];
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let page2 = vec![fruit::Model {
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id: 3,
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name: "Strawberry".into(),
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cake_id: Some(2),
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}];
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let page3 = Vec::<fruit::Model>::new();
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let db = MockDatabase::new()
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.append_query_results(vec![page1.clone(), page2.clone(), page3.clone()])
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.into_connection();
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(db, vec![page1, page2, page3])
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}
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fn setup_num_rows() -> (DatabaseConnection, i32) {
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let num_rows = 3;
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let db = MockDatabase::new()
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.append_query_results(vec![vec![maplit::btreemap! {
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"num_rows" => Into::<Value>::into(num_rows),
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}]])
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.into_connection();
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(db, num_rows)
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}
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#[async_std::test]
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async fn fetch_page() -> Result<(), SeaErr> {
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let (db, pages) = setup();
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let paginator = fruit::Entity::find().paginate(&db, 2);
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assert_eq!(paginator.fetch_page(0).await?, pages[0].clone());
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assert_eq!(paginator.fetch_page(1).await?, pages[1].clone());
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assert_eq!(paginator.fetch_page(2).await?, pages[2].clone());
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let mut select = SelectStatement::new()
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.exprs(vec![
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Expr::tbl(fruit::Entity, fruit::Column::Id),
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Expr::tbl(fruit::Entity, fruit::Column::Name),
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Expr::tbl(fruit::Entity, fruit::Column::CakeId),
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])
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.from(fruit::Entity)
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.to_owned();
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let query_builder = db.get_query_builder_backend();
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let stmts = vec![
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query_builder.build(select.clone().offset(0).limit(2)),
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query_builder.build(select.clone().offset(2).limit(2)),
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query_builder.build(select.offset(4).limit(2)),
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];
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assert_eq!(db.into_transaction_log(), Transaction::wrap(stmts));
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Ok(())
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}
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#[async_std::test]
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async fn fetch() -> Result<(), SeaErr> {
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let (db, pages) = setup();
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let mut paginator = fruit::Entity::find().paginate(&db, 2);
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assert_eq!(paginator.fetch().await?, pages[0].clone());
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paginator.next();
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assert_eq!(paginator.fetch().await?, pages[1].clone());
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paginator.next();
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assert_eq!(paginator.fetch().await?, pages[2].clone());
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let mut select = SelectStatement::new()
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.exprs(vec![
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Expr::tbl(fruit::Entity, fruit::Column::Id),
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Expr::tbl(fruit::Entity, fruit::Column::Name),
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Expr::tbl(fruit::Entity, fruit::Column::CakeId),
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])
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.from(fruit::Entity)
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.to_owned();
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let query_builder = db.get_query_builder_backend();
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let stmts = vec![
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query_builder.build(select.clone().offset(0).limit(2)),
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query_builder.build(select.clone().offset(2).limit(2)),
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query_builder.build(select.offset(4).limit(2)),
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];
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assert_eq!(db.into_transaction_log(), Transaction::wrap(stmts));
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Ok(())
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}
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#[async_std::test]
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async fn num_pages() -> Result<(), SeaErr> {
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let (db, num_rows) = setup_num_rows();
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let num_rows = num_rows as usize;
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let page_size = 2_usize;
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let num_pages = (num_rows / page_size) + (num_rows % page_size > 0) as usize;
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let paginator = fruit::Entity::find().paginate(&db, page_size);
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assert_eq!(paginator.num_pages().await?, num_pages);
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let sub_query = SelectStatement::new()
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.exprs(vec![
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Expr::tbl(fruit::Entity, fruit::Column::Id),
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Expr::tbl(fruit::Entity, fruit::Column::Name),
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Expr::tbl(fruit::Entity, fruit::Column::CakeId),
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])
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.from(fruit::Entity)
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.to_owned();
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let select = SelectStatement::new()
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.expr(Expr::cust("COUNT(*) AS num_rows"))
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.from_subquery(sub_query, Alias::new("sub_query"))
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.to_owned();
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let query_builder = db.get_query_builder_backend();
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let stmts = vec![query_builder.build(&select)];
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assert_eq!(db.into_transaction_log(), Transaction::wrap(stmts));
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Ok(())
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}
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#[async_std::test]
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async fn next_and_cur_page() -> Result<(), SeaErr> {
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let (db, _) = setup();
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let mut paginator = fruit::Entity::find().paginate(&db, 2);
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assert_eq!(paginator.cur_page(), 0);
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paginator.next();
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assert_eq!(paginator.cur_page(), 1);
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paginator.next();
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assert_eq!(paginator.cur_page(), 2);
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Ok(())
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}
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#[async_std::test]
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async fn fetch_and_next() -> Result<(), SeaErr> {
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let (db, pages) = setup();
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let mut paginator = fruit::Entity::find().paginate(&db, 2);
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assert_eq!(paginator.cur_page(), 0);
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assert_eq!(paginator.fetch_and_next().await?, Some(pages[0].clone()));
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assert_eq!(paginator.cur_page(), 1);
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assert_eq!(paginator.fetch_and_next().await?, Some(pages[1].clone()));
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assert_eq!(paginator.cur_page(), 2);
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assert_eq!(paginator.fetch_and_next().await?, None);
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let mut select = SelectStatement::new()
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.exprs(vec![
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Expr::tbl(fruit::Entity, fruit::Column::Id),
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Expr::tbl(fruit::Entity, fruit::Column::Name),
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Expr::tbl(fruit::Entity, fruit::Column::CakeId),
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])
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.from(fruit::Entity)
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.to_owned();
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let query_builder = db.get_query_builder_backend();
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let stmts = vec![
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query_builder.build(select.clone().offset(0).limit(2)),
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query_builder.build(select.clone().offset(2).limit(2)),
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query_builder.build(select.offset(4).limit(2)),
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];
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assert_eq!(db.into_transaction_log(), Transaction::wrap(stmts));
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Ok(())
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}
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#[async_std::test]
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async fn into_stream() -> Result<(), SeaErr> {
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let (db, pages) = setup();
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let mut fruit_stream = fruit::Entity::find().paginate(&db, 2).into_stream();
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assert_eq!(fruit_stream.try_next().await?, Some(pages[0].clone()));
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assert_eq!(fruit_stream.try_next().await?, Some(pages[1].clone()));
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assert_eq!(fruit_stream.try_next().await?, None);
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drop(fruit_stream);
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let mut select = SelectStatement::new()
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.exprs(vec![
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Expr::tbl(fruit::Entity, fruit::Column::Id),
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Expr::tbl(fruit::Entity, fruit::Column::Name),
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Expr::tbl(fruit::Entity, fruit::Column::CakeId),
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])
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.from(fruit::Entity)
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.to_owned();
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let query_builder = db.get_query_builder_backend();
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let stmts = vec![
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query_builder.build(select.clone().offset(0).limit(2)),
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query_builder.build(select.clone().offset(2).limit(2)),
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query_builder.build(select.offset(4).limit(2)),
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];
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assert_eq!(db.into_transaction_log(), Transaction::wrap(stmts));
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Ok(())
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}
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}
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