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use bonsaidb::{
core::{
connection::Connection,
document::{CollectionDocument, Emit},
schema::{
view::CollectionViewSchema, Collection, ReduceResult, SerializedCollection, View,
ViewMapResult, ViewMappedValue,
},
local::{
config::{Builder, StorageConfiguration},
Database,
};
use serde::{Deserialize, Serialize};
// begin rustme snippet: snippet-a
#[derive(Debug, Serialize, Deserialize, Collection)]
#[collection(name = "shapes", views = [ShapesByNumberOfSides])]
struct Shape {
pub sides: u32,
}
#[derive(Debug, Clone, View)]
#[view(collection = Shape, key = u32, value = usize, name = "by-number-of-sides")]
struct ShapesByNumberOfSides;
impl CollectionViewSchema for ShapesByNumberOfSides {
type View = Self;
fn map(&self, document: CollectionDocument<Shape>) -> ViewMapResult<Self::View> {
document
.header
.emit_key_and_value(document.contents.sides, 1)
fn reduce(
&self,
mappings: &[ViewMappedValue<Self>],
_rereduce: bool,
) -> ReduceResult<Self::View> {
Ok(mappings.iter().map(|m| m.value).sum())
// end rustme snippet
fn main() -> Result<(), bonsaidb::core::Error> {
// begin rustme snippet: snippet-b
let db = Database::open::<Shape>(StorageConfiguration::new("view-examples.bonsaidb"))?;
// Insert a new document into the Shape collection.
Shape { sides: 3 }.push_into(&db)?;
// Views in BonsaiDb are written using a Map/Reduce approach. In this
// example, we take a look at how document mapping can be used to filter and
// retrieve data
//
// Let's start by seeding the database with some shapes of various sizes:
for sides in 3..=20 {
Shape { sides }.push_into(&db)?;
// And, let's add a few shapes with the same number of sides
Shape { sides: 4 }.push_into(&db)?;
// At this point, our database should have 3 triangles:
// begin rustme snippet: snippet-c
let triangles = db.view::<ShapesByNumberOfSides>().with_key(3).query()?;
println!("Number of triangles: {}", triangles.len());
// What is returned is a list of entries containing the document id
// (source), the key of the entry, and the value of the entry:
println!("Triangles: {:#?}", triangles);
// If you want the associated documents, use query_with_collection_docs:
for entry in &db
.view::<ShapesByNumberOfSides>()
.with_key(3)
.query_with_collection_docs()?
{
println!(
"Shape ID {} has {} sides",
entry.document.header.id, entry.document.contents.sides
);
// The reduce() function takes the "values" emitted during the map()
// function, and reduces a list down to a single value. In this example, the
// reduce function is acting as a count. So, if you want to query for the
// number of shapes, we don't need to fetch all the records, we can just
// retrieve the result of the calculation directly.
// So, here we're using reduce() to count the number of shapes with 4 sides.
"Number of quads: {} (expected 2)",
db.view::<ShapesByNumberOfSides>().with_key(4).reduce()?
// Or, 5 shapes that are triangles or quads
"Number of quads and triangles: {} (expected 5)",
db.view::<ShapesByNumberOfSides>()
.with_keys([3, 4])
.reduce()?
// And, 10 shapes that have more than 10 sides
"Number of shapes with more than 10 sides: {} (expected 10)",
.with_key_range(11..u32::MAX)
Ok(())
#[test]
fn runs() {
drop(std::fs::remove_dir_all("view-examples.bonsaidb"));
main().unwrap()