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Make page size/limit for _changes configurable.

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Refactor handling of query args and building of links. This paves the way for more query args
This commit is contained in:
Magnus Hoff 2017-10-23 15:32:09 +02:00
parent 0f1e1f65ed
commit 955254335d
2 changed files with 114 additions and 24 deletions
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132
src/resources/changes_resource.rs
View file

@ -1,11 +1,14 @@
use diesel;
use futures::{self, Future};
use futures::future::{done, finished};
use hyper;
use hyper::header::ContentType;
use hyper::server::*;
use serde_urlencoded;
use assets::StyleCss;
use mimes::*;
use schema::article_revisions;
use site::Layout;
use state::State;
use web::{Resource, ResponseFuture};
@ -13,7 +16,7 @@ use web::{Resource, ResponseFuture};
use super::pagination::Pagination;
use super::TemporaryRedirectResource;
const PAGE_SIZE: i32 = 30;
const DEFAULT_LIMIT: i32 = 30;
type BoxResource = Box<Resource + Sync + Send>;
@ -22,6 +25,55 @@ pub struct ChangesLookup {
state: State,
}
// TODO: Optionally filter by article_id
// TODO: Optionally filter by author
#[derive(Serialize, Deserialize, Default)]
struct QueryParameters {
after: Option<i32>,
before: Option<i32>,
limit: Option<i32>,
}
impl QueryParameters {
fn pagination(self, pagination: Pagination<i32>) -> Self {
Self {
after: if let Pagination::After(x) = pagination { Some(x) } else { None },
before: if let Pagination::Before(x) = pagination { Some(x) } else { None },
..self
}
}
fn limit(self, limit: i32) -> Self {
Self {
limit: if limit != DEFAULT_LIMIT { Some(limit) } else { None },
..self
}
}
fn into_link(self) -> String {
let args = serde_urlencoded::to_string(self).expect("Serializing to String cannot fail");
if args.len() > 0 {
format!("?{}", args)
} else {
"_changes".to_owned()
}
}
}
fn apply_query_config<'a>(
query: article_revisions::BoxedQuery<'a, diesel::sqlite::Sqlite>,
limit: i32,
)
-> article_revisions::BoxedQuery<'a, diesel::sqlite::Sqlite>
{
use diesel::prelude::*;
query
.limit(limit as i64 + 1)
}
impl ChangesLookup {
pub fn new(state: State) -> ChangesLookup {
Self { state }
@ -33,32 +85,52 @@ impl ChangesLookup {
let state = self.state.clone();
Box::new(
done(pagination::from_str(query.unwrap_or("")).map_err(Into::into))
.and_then(move |pagination| match pagination {
done((|| {
let params: QueryParameters = serde_urlencoded::from_str(query.unwrap_or(""))?;
let pagination = pagination::from_fields(params.after, params.before)?;
let limit = match params.limit {
None => Ok(DEFAULT_LIMIT),
Some(x) if 1 <= x && x <= 100 => Ok(x),
_ => Err("`limit` argument must be in range [1, 100]"),
}?;
Ok((pagination, limit))
})())
.and_then(move |(pagination, limit)| match pagination {
Pagination::After(x) => Box::new(
state.query_article_revision_stubs(move |query| {
use diesel::prelude::*;
use schema::article_revisions::dsl::*;
query
.limit(PAGE_SIZE as i64 + 1)
apply_query_config(query, limit)
.filter(sequence_number.gt(x))
.order(sequence_number.asc())
}).and_then(|mut data| {
let extra_element = if data.len() > PAGE_SIZE as usize {
}).and_then(move |mut data| {
let extra_element = if data.len() > limit as usize {
data.pop()
} else {
None
};
Ok(Some(match extra_element {
Some(x) => Box::new(TemporaryRedirectResource::new(format!("?before={}", x.sequence_number))) as BoxResource,
None => Box::new(TemporaryRedirectResource::new(format!("_changes"))) as BoxResource,
Some(x) => Box::new(TemporaryRedirectResource::new(
QueryParameters::default()
.limit(limit)
.pagination(Pagination::Before(x.sequence_number))
.into_link()
)) as BoxResource,
None => Box::new(TemporaryRedirectResource::new(
QueryParameters::default()
.limit(limit)
.into_link()
)) as BoxResource,
}))
})
) as Box<Future<Item=Option<BoxResource>, Error=::web::Error>>,
Pagination::Before(x) => Box::new(finished(Some(Box::new(ChangesResource::new(state, Some(x))) as BoxResource))),
Pagination::None => Box::new(finished(Some(Box::new(ChangesResource::new(state, None)) as BoxResource))),
Pagination::Before(x) => Box::new(finished(Some(Box::new(ChangesResource::new(state, Some(x), limit)) as BoxResource))),
Pagination::None => Box::new(finished(Some(Box::new(ChangesResource::new(state, None, limit)) as BoxResource))),
})
)
}
@ -67,11 +139,21 @@ impl ChangesLookup {
pub struct ChangesResource {
state: State,
before: Option<i32>,
limit: i32,
}
impl ChangesResource {
pub fn new(state: State, before: Option<i32>) -> Self {
Self { state, before }
pub fn new(state: State, before: Option<i32>, limit: i32) -> Self {
Self { state, before, limit }
}
fn query_args(&self) -> QueryParameters {
QueryParameters {
after: None,
before: self.before,
..QueryParameters::default()
}
.limit(self.limit)
}
}
@ -117,13 +199,13 @@ impl Resource for ChangesResource {
}
let before = self.before.clone();
let limit = self.limit;
let data = self.state.query_article_revision_stubs(move |query| {
use diesel::prelude::*;
use schema::article_revisions::dsl::*;
let query = query
.order(sequence_number.desc())
.limit(PAGE_SIZE as i64 + 1);
let query = apply_query_config(query, limit)
.order(sequence_number.desc());
match before {
Some(x) => query.filter(sequence_number.lt(x)),
@ -142,7 +224,7 @@ impl Resource for ChangesResource {
unimplemented!("Cannot deal with empty result sets");
}
let extra_element = if data.len() > PAGE_SIZE as usize {
let extra_element = if data.len() > self.limit as usize {
data.pop()
} else {
None
@ -151,19 +233,23 @@ impl Resource for ChangesResource {
let (newer, older) = match self.before {
Some(x) => (
Some(NavLinks {
more: format!("?after={}", x - 1),
end: format!("_changes"),
more: self.query_args().pagination(Pagination::After(x-1)).into_link(),
end: self.query_args().pagination(Pagination::None).into_link(),
}),
extra_element.map(|_| NavLinks {
more: format!("?before={}", data.last().unwrap().sequence_number),
end: format!("?after=0"),
more: self.query_args()
.pagination(Pagination::Before(data.last().unwrap().sequence_number))
.into_link(),
end: self.query_args().pagination(Pagination::After(0)).into_link(),
})
),
None => (
None,
extra_element.map(|_| NavLinks {
more: format!("?before={}", data.last().unwrap().sequence_number),
end: format!("?after=0"),
more: self.query_args()
.pagination(Pagination::Before(data.last().unwrap().sequence_number))
.into_link(),
end: self.query_args().pagination(Pagination::After(0)).into_link(),
}),
),
};

6
src/resources/pagination.rs
View file

@ -42,7 +42,11 @@ impl<T> PaginationStruct<T> {
}
}
pub fn from_str<'a, T: serde::Deserialize<'a>>(s: &'a str) -> Result<Pagination<T>, Error> {
pub fn _from_str<'a, T: serde::Deserialize<'a>>(s: &'a str) -> Result<Pagination<T>, Error> {
let pagination: PaginationStruct<T> = serde_urlencoded::from_str(s).map_err(|_| Error)?; // TODO Proper error reporting
Ok(pagination.into_enum()?)
}
pub fn from_fields<T>(after: Option<T>, before: Option<T>) -> Result<Pagination<T>, Error> {
Ok(PaginationStruct { after, before }.into_enum()?)
}