geojson/

geojson.rs

// Copyright 2015 The GeoRust Developers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::errors::{Error, Result};
use crate::{Feature, FeatureCollection, Geometry};
use serde::{Deserialize, Serialize};
use std::convert::TryFrom;
use std::fmt;
use std::iter::FromIterator;
use std::str::FromStr;

/// GeoJSON Objects
///
/// ```
/// use geojson::{Feature, FeatureCollection, GeoJson, Geometry};
/// use std::convert::TryInto;
///
/// // Parsing a Geometry
/// let geometry_str = r#"{
///    "type": "Point",
///    "coordinates": [102.0, 0.5]
/// }"#;
/// let geometry: Geometry = geometry_str.parse().unwrap();
///
/// // Parsing a Feature
/// let feature_str = r#"{
///     "type": "Feature",
///     "geometry": {
///         "type": "Point",
///         "coordinates": [102.0, 0.5]
///     },
///     "properties": null
/// }"#;
/// let feature: Feature = feature_str.parse().unwrap();
///
/// // Parsing a FeatureCollection
/// let feature_collection_str = r#"{
///     "type": "FeatureCollection",
///     "features": [{
///         "type": "Feature",
///         "geometry": {
///             "type": "Point",
///             "coordinates": [102.0, 0.5]
///         },
///         "properties": null
///     }]
/// }"#;
/// let feature_collection: FeatureCollection = feature_collection_str.parse().unwrap();
///
/// // When you're not sure what you're getting, use `GeoJson`.
/// for geojson_str in [feature_str, geometry_str, feature_collection_str] {
///     let geojson: GeoJson = geojson_str.parse().unwrap();
///     match geojson {
///         GeoJson::Geometry(geometry) => println!("geometry: {geometry:?}"),
///         GeoJson::Feature(feature) => println!("feature: {feature:?}"),
///         GeoJson::FeatureCollection(feature_collection) => {
///             println!("feature_collection: {feature_collection:?}")
///         }
///     }
/// }
///
/// // Easily convert a `Feature`, `FeatureCollection`, or `Geometry` into a `GeoJson`
/// let geojson: GeoJson = feature.into();
/// // Fallibly convert a GeoJson to its inner variant
/// let feature: Feature = geojson.try_into().expect("expected a Feature");
/// ```
/// [GeoJSON Format Specification § 3](https://tools.ietf.org/html/rfc7946#section-3)
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
#[serde(untagged, try_from = "deserialize::RawGeoJson")]
pub enum GeoJson {
    Geometry(Geometry),
    Feature(Feature),
    FeatureCollection(FeatureCollection),
}

impl<G: Into<Geometry>> From<G> for GeoJson {
    fn from(geometry: G) -> Self {
        GeoJson::Geometry(geometry.into())
    }
}

impl<G: Into<Geometry>> FromIterator<G> for GeoJson {
    fn from_iter<I: IntoIterator<Item = G>>(iter: I) -> Self {
        let geometry_collection = Geometry::new_geometry_collection(iter);
        GeoJson::Geometry(geometry_collection)
    }
}

impl From<Feature> for GeoJson {
    fn from(feature: Feature) -> Self {
        GeoJson::Feature(feature)
    }
}

impl From<FeatureCollection> for GeoJson {
    fn from(feature_collection: FeatureCollection) -> GeoJson {
        GeoJson::FeatureCollection(feature_collection)
    }
}

impl From<Vec<Feature>> for GeoJson {
    fn from(features: Vec<Feature>) -> GeoJson {
        GeoJson::from(features.into_iter().collect::<FeatureCollection>())
    }
}

impl TryFrom<GeoJson> for Geometry {
    type Error = Error;
    fn try_from(value: GeoJson) -> Result<Self> {
        match value {
            GeoJson::Geometry(g) => Ok(g),
            GeoJson::Feature(_) => Err(Error::ExpectedType {
                expected: "Geometry".to_string(),
                actual: "Feature".to_string(),
            }),
            GeoJson::FeatureCollection(_) => Err(Error::ExpectedType {
                expected: "Geometry".to_string(),
                actual: "FeatureCollection".to_string(),
            }),
        }
    }
}

impl TryFrom<GeoJson> for Feature {
    type Error = Error;
    fn try_from(value: GeoJson) -> Result<Self> {
        match value {
            GeoJson::Geometry(_) => Err(Error::ExpectedType {
                expected: "Feature".to_string(),
                actual: "Geometry".to_string(),
            }),
            GeoJson::Feature(f) => Ok(f),
            GeoJson::FeatureCollection(_) => Err(Error::ExpectedType {
                expected: "Feature".to_string(),
                actual: "FeatureCollection".to_string(),
            }),
        }
    }
}

impl TryFrom<GeoJson> for FeatureCollection {
    type Error = Error;
    fn try_from(value: GeoJson) -> Result<Self> {
        match value {
            GeoJson::Geometry(_) => Err(Error::ExpectedType {
                expected: "FeatureCollection".to_string(),
                actual: "Geometry".to_string(),
            }),
            GeoJson::Feature(_) => Err(Error::ExpectedType {
                expected: "FeatureCollection".to_string(),
                actual: "Feature".to_string(),
            }),
            GeoJson::FeatureCollection(f) => Ok(f),
        }
    }
}

impl GeoJson {
    // Deserialize a GeoJson object from an IO stream of JSON
    pub fn from_reader<R>(rdr: R) -> serde_json::Result<Self>
    where
        R: std::io::Read,
    {
        serde_json::from_reader(rdr)
    }

    /// Convenience wrapper for [serde_json::to_string_pretty()]
    pub fn to_string_pretty(self) -> Result<String> {
        ::serde_json::to_string_pretty(&self)
            .map_err(Error::MalformedGeoJson)
            .map(|s| s.to_string())
    }
}

/// # Example
///```
/// use geojson::GeoJson;
/// use std::str::FromStr;
///
/// let geojson_str = r#"{
///   "type": "FeatureCollection",
///   "features": [
///     {
///       "type": "Feature",
///       "properties": {},
///       "geometry": {
///         "type": "Point",
///         "coordinates": [
///           -0.13583511114120483,
///           51.5218870403801
///         ]
///       }
///     }
///   ]
/// }
/// "#;
/// let geo_json = GeoJson::from_str(&geojson_str).unwrap();
/// if let GeoJson::FeatureCollection(collection) = geo_json {
///     assert_eq!(1, collection.features.len());
/// } else {
///     panic!("expected feature collection");
/// }
/// ```
impl FromStr for GeoJson {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self> {
        Ok(serde_json::from_str(s)?)
    }
}

impl fmt::Display for GeoJson {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        ::serde_json::to_string(self)
            .map_err(|_| fmt::Error)
            .and_then(|s| f.write_str(&s))
    }
}

impl fmt::Display for Feature {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        ::serde_json::to_string(self)
            .map_err(|_| fmt::Error)
            .and_then(|s| f.write_str(&s))
    }
}

impl fmt::Display for Geometry {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        ::serde_json::to_string(self)
            .map_err(|_| fmt::Error)
            .and_then(|s| f.write_str(&s))
    }
}

impl fmt::Display for FeatureCollection {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        ::serde_json::to_string(self)
            .map_err(|_| fmt::Error)
            .and_then(|s| f.write_str(&s))
    }
}

mod deserialize {
    use crate::geometry::deserialize::{Coordinates, GeometryType, RawGeometry};
    use crate::util::normalize_foreign_members;
    use crate::{Bbox, Error, Feature, FeatureCollection, GeoJson, Geometry, JsonObject, feature};
    use serde::Deserialize;
    use std::convert::TryFrom;

    #[derive(Debug, Clone, PartialEq, Deserialize)]
    enum GeoJsonType {
        Feature,
        FeatureCollection,
        Point,
        LineString,
        Polygon,
        MultiPoint,
        MultiLineString,
        MultiPolygon,
        GeometryCollection,
    }

    impl GeoJsonType {
        /// Convert to GeometryType if this is a geometry variant
        fn as_geometry_type(&self) -> Option<GeometryType> {
            match self {
                GeoJsonType::Point => Some(GeometryType::Point),
                GeoJsonType::LineString => Some(GeometryType::LineString),
                GeoJsonType::Polygon => Some(GeometryType::Polygon),
                GeoJsonType::MultiPoint => Some(GeometryType::MultiPoint),
                GeoJsonType::MultiLineString => Some(GeometryType::MultiLineString),
                GeoJsonType::MultiPolygon => Some(GeometryType::MultiPolygon),
                GeoJsonType::GeometryCollection => Some(GeometryType::GeometryCollection),
                GeoJsonType::Feature | GeoJsonType::FeatureCollection => None,
            }
        }
    }

    /// Internal struct for deserializing any GeoJSON object before converting to GeoJson.
    /// This captures all possible fields that can appear in any GeoJSON object type.
    #[derive(Debug, Clone, Deserialize)]
    #[serde(expecting = "GeoJson object")]
    pub(crate) struct RawGeoJson {
        r#type: GeoJsonType,

        // Common field
        bbox: Option<Bbox>,

        // Geometry field (except GeometryCollection)
        coordinates: Option<Coordinates>,

        // GeometryCollection field
        geometries: Option<Vec<Geometry>>,

        // FeatureCollection field
        features: Option<Vec<Feature>>,

        // Feature fields
        id: Option<feature::Id>,
        geometry: Option<Geometry>,
        properties: Option<JsonObject>,

        // Foreign members (captures all other fields)
        #[serde(flatten)]
        foreign_members: Option<JsonObject>,
    }

    impl TryFrom<RawGeoJson> for GeoJson {
        type Error = Error;

        fn try_from(mut raw: RawGeoJson) -> crate::Result<Self> {
            normalize_foreign_members(&mut raw.foreign_members);

            match raw.r#type {
                GeoJsonType::FeatureCollection => {
                    let features = raw.features.ok_or_else(|| {
                        use serde::de::Error as _;
                        Error::MalformedGeoJson(serde_json::Error::missing_field("features"))
                    })?;
                    Ok(GeoJson::FeatureCollection(FeatureCollection {
                        bbox: raw.bbox,
                        features,
                        foreign_members: raw.foreign_members,
                    }))
                }

                GeoJsonType::Feature => Ok(GeoJson::Feature(Feature {
                    bbox: raw.bbox,
                    geometry: raw.geometry,
                    id: raw.id,
                    properties: raw.properties,
                    foreign_members: raw.foreign_members,
                })),

                // Delegate all geometry types to RawGeometry
                geojson_type => {
                    let geometry_type = geojson_type.as_geometry_type().expect(
                        "as_geometry_type returns Some for all variants except Feature/FeatureCollection",
                    );
                    let raw_geom = RawGeometry {
                        r#type: geometry_type,
                        coordinates: raw.coordinates,
                        geometries: raw.geometries,
                        bbox: raw.bbox,
                        foreign_members: raw.foreign_members,
                    };
                    Ok(GeoJson::Geometry(Geometry::try_from(raw_geom)?))
                }
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::{Error, Feature, FeatureCollection, GeoJson, Geometry};
    use serde_json::json;
    use std::str::FromStr;

    #[test]
    fn test_geojson_from_reader() {
        let json_str = r#"{
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [102.0, 0.5]
            },
            "properties": null
        }"#;

        let actual = GeoJson::from_reader(json_str.as_bytes()).unwrap();
        let actual_as_json = serde_json::to_value(actual).unwrap();
        let expected = json!({
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [102.0, 0.5]
            },
            "properties": null
        });
        assert_eq!(actual_as_json, expected);
    }

    #[test]
    fn test_geojson_from_features() {
        let features: Vec<Feature> = vec![
            Geometry::new_point([0., 0., 0.]).into(),
            Geometry::new_point([1., 1., 1.]).into(),
        ];

        let geojson: GeoJson = features.into();
        assert_eq!(
            geojson,
            GeoJson::FeatureCollection(FeatureCollection {
                features: vec![
                    Feature {
                        bbox: None,
                        geometry: Some(Geometry::new_point([0., 0., 0.])),
                        id: None,
                        properties: None,
                        foreign_members: None,
                    },
                    Feature {
                        bbox: None,
                        geometry: Some(Geometry::new_point([1., 1., 1.])),
                        id: None,
                        properties: None,
                        foreign_members: None,
                    },
                ],
                bbox: None,
                foreign_members: None,
            })
        );
    }

    #[test]
    fn test_missing_properties_key() {
        let json_str = json!({
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [102.0, 0.5]
            },
        })
        .to_string();

        let geojson = GeoJson::from_str(&json_str).unwrap();
        assert_eq!(
            geojson,
            GeoJson::Feature(Feature {
                bbox: None,
                geometry: Some(Geometry::new_point([102.0, 0.5])),
                id: None,
                properties: None,
                foreign_members: None,
            })
        );
    }

    #[test]
    fn test_invalid_json() {
        let geojson_str = r#"{
           "type": "FeatureCollection",
           "features": [
             !INTENTIONAL_TYPO! {
               "type": "Feature",
               "properties": {},
               "geometry": {
                 "type": "Point",
                 "coordinates": [
                   -0.13583511114120483,
                   51.5218870403801
                 ]
               }
             }
           ]
        }"#;
        assert!(matches!(
            GeoJson::from_str(geojson_str),
            Err(Error::MalformedGeoJson(_))
        ))
    }

    #[test]
    fn geojson_with_invalid_type() {
        let geojson_str = json!({
           "type": "TYPO-FeatureCollection",
            "features": []
        })
        .to_string();

        let err = GeoJson::from_str(&geojson_str).unwrap_err();
        assert!(matches!(err, Error::MalformedGeoJson(_)));
    }

    #[test]
    fn geojson_with_missing_type() {
        let geojson_str = json!({
            "features": []
        })
        .to_string();

        let err = GeoJson::from_str(&geojson_str).unwrap_err();
        assert!(matches!(err, Error::MalformedGeoJson(_)));
    }

    #[test]
    fn not_an_object() {
        let geojson_str = "[]";
        let err = GeoJson::from_str(geojson_str).unwrap_err();
        assert!(matches!(err, Error::MalformedGeoJson(_)));
        assert!(format!("{err}").contains("expected GeoJson object"));
    }
}