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use crate::de::deserialize_feature_collection;
use crate::{Feature, Result};
use serde::de::DeserializeOwned;
use std::io::Read;
/// Enumerates individual Features from a GeoJSON FeatureCollection
pub struct FeatureReader<R> {
reader: R,
}
impl<R: Read> FeatureReader<R> {
/// Create a FeatureReader from the given `reader`.
pub fn from_reader(reader: R) -> Self {
Self { reader }
}
/// Iterate over the individual [`Feature`s](Feature) of a FeatureCollection.
///
/// If instead you'd like to deserialize directly to your own struct, see [`FeatureReader::deserialize`].
///
/// # Examples
///
/// ```
/// let feature_collection_string = r#"{
/// "type": "FeatureCollection",
/// "features": [
/// {
/// "type": "Feature",
/// "geometry": { "type": "Point", "coordinates": [125.6, 10.1] },
/// "properties": {
/// "name": "Dinagat Islands",
/// "age": 123
/// }
/// },
/// {
/// "type": "Feature",
/// "geometry": { "type": "Point", "coordinates": [2.3, 4.5] },
/// "properties": {
/// "name": "Neverland",
/// "age": 456
/// }
/// }
/// ]
/// }"#
/// .as_bytes();
/// let io_reader = std::io::BufReader::new(feature_collection_string);
///
/// use geojson::FeatureReader;
/// let feature_reader = FeatureReader::from_reader(io_reader);
/// for feature in feature_reader.features() {
/// let feature = feature.expect("valid geojson feature");
///
/// let name = feature.property("name").unwrap().as_str().unwrap();
/// let age = feature.property("age").unwrap().as_u64().unwrap();
///
/// if name == "Dinagat Islands" {
/// assert_eq!(123, age);
/// } else if name == "Neverland" {
/// assert_eq!(456, age);
/// } else {
/// panic!("unexpected name: {}", name);
/// }
/// }
/// ```
pub fn features(self) -> impl Iterator<Item = Result<Feature>> {
#[allow(deprecated)]
crate::FeatureIterator::new(self.reader)
}
/// Deserialize the features of FeatureCollection into your own custom
/// struct using the [`serde`](../../serde) crate.
///
/// # Examples
///
/// Your struct must implement or derive [`serde::Deserialize`].
///
/// If you have enabled the `geo-types` feature, which is enabled by default, you can
/// deserialize directly to a useful geometry type.
///
/// ```rust,ignore
/// use geojson::{FeatureReader, de::deserialize_geometry};
///
/// #[derive(serde::Deserialize)]
/// struct MyStruct {
/// #[serde(deserialize_with = "deserialize_geometry")]
/// geometry: geo_types::Point<f64>,
/// name: String,
/// age: u64,
/// }
/// ```
///
/// Then you can deserialize the FeatureCollection directly to your type.
#[cfg_attr(feature = "geo-types", doc = "```")]
#[cfg_attr(not(feature = "geo-types"), doc = "```ignore")]
/// let feature_collection_string = r#"{
/// "type": "FeatureCollection",
/// "features": [
/// {
/// "type": "Feature",
/// "geometry": { "type": "Point", "coordinates": [125.6, 10.1] },
/// "properties": {
/// "name": "Dinagat Islands",
/// "age": 123
/// }
/// },
/// {
/// "type": "Feature",
/// "geometry": { "type": "Point", "coordinates": [2.3, 4.5] },
/// "properties": {
/// "name": "Neverland",
/// "age": 456
/// }
/// }
/// ]
/// }"#.as_bytes();
/// let io_reader = std::io::BufReader::new(feature_collection_string);
/// #
/// # use geojson::{FeatureReader, de::deserialize_geometry};
/// #
/// # #[derive(serde::Deserialize)]
/// # struct MyStruct {
/// # #[serde(deserialize_with = "deserialize_geometry")]
/// # geometry: geo_types::Point<f64>,
/// # name: String,
/// # age: u64,
/// # }
///
/// let feature_reader = FeatureReader::from_reader(io_reader);
/// for feature in feature_reader.deserialize::<MyStruct>().unwrap() {
/// let my_struct = feature.expect("valid geojson feature");
///
/// if my_struct.name == "Dinagat Islands" {
/// assert_eq!(123, my_struct.age);
/// } else if my_struct.name == "Neverland" {
/// assert_eq!(456, my_struct.age);
/// } else {
/// panic!("unexpected name: {}", my_struct.name);
/// }
/// }
/// ```
///
/// If you're not using [`geo-types`](geo_types), you can deserialize to a `geojson::Geometry` instead.
/// ```rust,ignore
/// use serde::Deserialize;
/// #[derive(Deserialize)]
/// struct MyStruct {
/// geometry: geojson::Geometry,
/// name: String,
/// age: u64,
/// }
/// ```
pub fn deserialize<D: DeserializeOwned>(self) -> Result<impl Iterator<Item = Result<D>>> {
deserialize_feature_collection(self.reader)
}
}
#[cfg(test)]
mod tests {
use super::*;
use serde::Deserialize;
use serde_json::json;
#[derive(Deserialize)]
struct MyRecord {
geometry: crate::Geometry,
name: String,
age: u64,
}
fn feature_collection_string() -> String {
json!({
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [125.6, 10.1]
},
"properties": {
"name": "Dinagat Islands",
"age": 123
}
},
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [2.3, 4.5]
},
"properties": {
"name": "Neverland",
"age": 456
}
}
]
})
.to_string()
}
#[test]
#[cfg(feature = "geo-types")]
fn deserialize_into_type() {
let feature_collection_string = feature_collection_string();
let mut bytes_reader = feature_collection_string.as_bytes();
let feature_reader = FeatureReader::from_reader(&mut bytes_reader);
let records: Vec<MyRecord> = feature_reader
.deserialize()
.expect("a valid feature collection")
.map(|result| result.expect("a valid feature"))
.collect();
assert_eq!(records.len(), 2);
assert_eq!(
records[0].geometry,
(&geo_types::point!(x: 125.6, y: 10.1)).into()
);
assert_eq!(records[0].name, "Dinagat Islands");
assert_eq!(records[0].age, 123);
assert_eq!(
records[1].geometry,
(&geo_types::point!(x: 2.3, y: 4.5)).into()
);
assert_eq!(records[1].name, "Neverland");
assert_eq!(records[1].age, 456);
}
}