fix(core): remove extensions vec from asset

Inheritence wasn't ever going to work, was it?

core/CHANGELOG.md

@@ -17,6 +17,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - `stac::geoparquet::Compression`, even if geoparquet is not enabled ([#396](https://github.com/stac-utils/stac-rs/pull/396))
 - `Type` ([#397](https://github.com/stac-utils/stac-rs/pull/397))
 - `Collection::item_assets` and `ItemAsset` ([#404](https://github.com/stac-utils/stac-rs/pull/404))
+- A few extension methods on `Fields` ([#405](https://github.com/stac-utils/stac-rs/pull/405))
 
 ### Changed
 
@@ -26,6 +27,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Removed
 
 - `Error::ReqwestNotEnabled` and `Error::GdalNotEnabled` ([#396](https://github.com/stac-utils/stac-rs/pull/382))
+- `Asset::extensions` ([#405](https://github.com/stac-utils/stac-rs/pull/405))
 
 ## [0.9.0] - 2024-09-05
 

core/src/asset.rs

@@ -1,4 +1,4 @@
-use crate::{Band, DataType, Extensions, Fields, Statistics};
+use crate::{Band, DataType, Fields, Statistics};
 use serde::{Deserialize, Serialize};
 use serde_json::{Map, Value};
 use std::collections::HashMap;
@@ -80,9 +80,6 @@ pub struct Asset {
     /// Additional fields on the asset.
     #[serde(flatten)]
     pub additional_fields: Map<String, Value>,
-
-    #[serde(skip)]
-    extensions: Vec<String>,
 }
 
 /// Trait implemented by anything that has assets.
@@ -141,7 +138,6 @@ impl Asset {
             statistics: None,
             unit: None,
             additional_fields: Map::new(),
-            extensions: Vec::new(),
         }
     }
 
@@ -172,15 +168,6 @@ impl Fields for Asset {
     }
 }
 
-impl Extensions for Asset {
-    fn extensions(&self) -> &Vec<String> {
-        &self.extensions
-    }
-    fn extensions_mut(&mut self) -> &mut Vec<String> {
-        &mut self.extensions
-    }
-}
-
 impl From<String> for Asset {
     fn from(value: String) -> Self {
         Asset::new(value)

core/src/extensions/authentication.rs

@@ -167,25 +167,21 @@ impl Extension for Authentication {
 #[cfg(test)]
 mod tests {
     use super::{Authentication, In, Scheme};
-    use crate::{Collection, Extensions, Item};
+    use crate::{Collection, Fields, Item};
     use serde_json::json;
 
     #[test]
     fn collection() {
         let collection: Collection = crate::read("data/auth/collection.json").unwrap();
-        let authentication: Authentication = collection.extension().unwrap().unwrap();
+        let authentication: Authentication = collection.extension().unwrap();
         let oauth = authentication.schemes.get("oauth").unwrap();
         let _ = oauth.flows.get("authorizationCode").unwrap();
-        // FIXME: assets should be able to have extensions from their parent item
-        // let asset = collection.assets.get("example").unwrap();
-        // let authentication: Authentication = asset.extension().unwrap().unwrap();
-        // assert_eq!(authentication.refs, vec!["signed_url_auth".to_string()]);
     }
 
     #[test]
     fn item() {
         let collection: Item = crate::read("data/auth/item.json").unwrap();
-        let authentication: Authentication = collection.extension().unwrap().unwrap();
+        let authentication: Authentication = collection.extension().unwrap();
         let _ = authentication.schemes.get("none").unwrap();
     }
 

core/src/extensions/electro_optical.rs

@@ -72,11 +72,11 @@ impl Extension for ElectroOptical {
 #[cfg(test)]
 mod tests {
     use super::ElectroOptical;
-    use crate::{Extensions, Item};
+    use crate::{Fields, Item};
 
     #[test]
     fn item() {
         let item: Item = crate::read("data/eo/item.json").unwrap();
-        let _: ElectroOptical = item.extension().unwrap().unwrap();
+        let _: ElectroOptical = item.extension().unwrap();
     }
 }

core/src/extensions/mod.rs

@@ -122,26 +122,6 @@ pub trait Extensions: Fields {
             .any(|extension| extension.starts_with(E::identifier_prefix()))
     }
 
-    /// Gets an extension's data.
-    ///
-    /// Returns `Ok(None)` if the object doesn't have the given extension.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use stac::{Item, extensions::{Projection, Extensions}};
-    /// let item: Item = stac::read("examples/extensions-collection/proj-example/proj-example.json").unwrap();
-    /// let projection: Projection = item.extension().unwrap().unwrap();
-    /// assert_eq!(projection.code.unwrap(), "EPSG:32614");
-    /// ```
-    fn extension<E: Extension>(&self) -> Result<Option<E>> {
-        if self.has_extension::<E>() {
-            self.fields_with_prefix(E::PREFIX).map(|v| Some(v))
-        } else {
-            Ok(None)
-        }
-    }
-
     /// Adds an extension's identifier to this object.
     ///
     /// # Examples
@@ -169,10 +149,9 @@ pub trait Extensions: Fields {
     /// item.set_extension(projection).unwrap();
     /// ```
     fn set_extension<E: Extension>(&mut self, extension: E) -> Result<()> {
-        self.remove_extension::<E>();
         self.extensions_mut().push(E::IDENTIFIER.to_string());
         self.extensions_mut().dedup();
-        self.set_fields_with_prefix(E::PREFIX, extension)
+        Fields::set_extension(self, extension)
     }
 
     /// Removes this extension and all of its fields from this object.
@@ -187,8 +166,7 @@ pub trait Extensions: Fields {
     /// assert!(!item.has_extension::<Projection>());
     /// ```
     fn remove_extension<E: Extension>(&mut self) {
-        // TODO how do we handle removing from assets when this is done on an item?
-        self.remove_fields_with_prefix(E::PREFIX);
+        Fields::remove_extension::<E>(self);
         self.extensions_mut()
             .retain(|extension| !extension.starts_with(E::identifier_prefix()))
     }
@@ -220,13 +198,13 @@ mod tests {
 
     #[test]
     fn set_extension_on_asset() {
+        use crate::Fields;
+
         let mut asset = Asset::new("a/href.tif");
-        assert!(!asset.has_extension::<Raster>());
         let mut band = Band::default();
         band.unit = Some("parsecs".to_string());
         let raster = Raster { bands: vec![band] };
         asset.set_extension(raster).unwrap();
-        assert!(asset.has_extension::<Raster>());
         let mut item = Item::new("an-id");
         let _ = item.assets.insert("data".to_string(), asset);
     }

core/src/extensions/projection.rs

@@ -123,6 +123,22 @@ impl Projection {
             Ok(None)
         }
     }
+
+    /// Returns true if this projection structure is empty.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use stac::extensions::Projection;
+    ///
+    /// let projection = Projection::default();
+    /// assert!(projection.is_empty());
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        serde_json::to_value(self)
+            .map(|v| v == Value::Object(Default::default()))
+            .unwrap_or(true)
+    }
 }
 
 impl Extension for Projection {
@@ -134,7 +150,7 @@ impl Extension for Projection {
 #[cfg(test)]
 mod tests {
     use super::Projection;
-    use crate::{Extensions, Item};
+    use crate::{Fields, Item};
 
     #[cfg(feature = "gdal")]
     #[test]
@@ -162,7 +178,7 @@ mod tests {
     fn example() {
         let item: Item =
             crate::read("examples/extensions-collection/proj-example/proj-example.json").unwrap();
-        let projection = item.extension::<Projection>().unwrap().unwrap();
+        let projection = item.extension::<Projection>().unwrap();
         assert_eq!(projection.code.unwrap(), "EPSG:32614");
     }
 }

core/src/extensions/raster.rs

@@ -119,6 +119,24 @@ impl Extension for Raster {
     const PREFIX: &'static str = "raster";
 }
 
+impl Raster {
+    /// Returns true if this raster structure is empty.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use stac::extensions::Raster;
+    ///
+    /// let projection = Raster::default();
+    /// assert!(projection.is_empty());
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        serde_json::to_value(self)
+            .map(|v| v == serde_json::Value::Object(Default::default()))
+            .unwrap_or(true)
+    }
+}
+
 #[cfg(feature = "gdal")]
 impl From<gdal::raster::GdalDataType> for DataType {
     fn from(value: gdal::raster::GdalDataType) -> Self {

core/src/fields.rs

@@ -1,4 +1,4 @@
-use crate::{Error, Result};
+use crate::{Error, Extension, Result};
 use serde::{de::DeserializeOwned, Serialize};
 use serde_json::{json, Map, Value};
 
@@ -124,11 +124,59 @@ pub trait Fields {
     /// use stac::{Fields, Item, extensions::Projection};
     /// let projection = Projection { code: Some("EPSG:4326".to_string()), ..Default::default() };
     /// let mut item = Item::new("an-id");
-    /// item.remove_fields_with_prefix("proj");  // Prefer `Extensions::remove_extension`
+    /// item.remove_fields_with_prefix("proj");  // Prefer `Fields::remove_extension`
     /// ```
     fn remove_fields_with_prefix(&mut self, prefix: &str) {
         let prefix = format!("{}:", prefix);
         self.fields_mut()
             .retain(|key, _| !(key.starts_with(&prefix) && key.len() > prefix.len()));
     }
+
+    /// Gets an extension's data.
+    ///
+    /// Returns `Ok(None)` if the object doesn't have the given extension.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use stac::{Item, Fields, extensions::Projection};
+    /// let item: Item = stac::read("examples/extensions-collection/proj-example/proj-example.json").unwrap();
+    /// let projection: Projection = item.extension().unwrap();
+    /// assert_eq!(projection.code.unwrap(), "EPSG:32614");
+    /// ```
+    fn extension<E: Extension>(&self) -> Result<E> {
+        self.fields_with_prefix(E::PREFIX)
+    }
+
+    /// Sets an extension's data into this object.
+    ///
+    /// This will remove any previous fields from this extension
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use stac::{Item, Fields, extensions::Projection};
+    /// let mut item = Item::new("an-id");
+    /// let projection = Projection { code: Some("EPSG:4326".to_string()), ..Default::default() };
+    /// item.set_extension(projection).unwrap();
+    /// ```
+    fn set_extension<E: Extension>(&mut self, extension: E) -> Result<()> {
+        self.remove_extension::<E>();
+        self.set_fields_with_prefix(E::PREFIX, extension)
+    }
+
+    /// Removes all of the extension's fields from this object.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use stac::{Item, extensions::{Projection, Extensions}};
+    /// let mut item: Item = stac::read("examples/extensions-collection/proj-example/proj-example.json").unwrap();
+    /// assert!(item.has_extension::<Projection>());
+    /// item.remove_extension::<Projection>();
+    /// assert!(!item.has_extension::<Projection>());
+    /// ```
+    fn remove_extension<E: Extension>(&mut self) {
+        self.remove_fields_with_prefix(E::PREFIX);
+    }
 }

core/src/gdal.rs

@@ -6,7 +6,7 @@ use crate::{
         raster::{Band, Raster, Statistics},
         Projection,
     },
-    Asset, Bbox, Extensions, Item, Result,
+    Asset, Bbox, Extensions, Fields, Item, Result,
 };
 use gdal::{
     spatial_ref::{CoordTransform, SpatialRef},
@@ -44,14 +44,15 @@ pub fn update_item(
     let mut bbox = Bbox::new(180., 90., -180., 90.); // Intentionally invalid bbox so the first update always takes
     for asset in item.assets.values_mut() {
         update_asset(asset, force_statistics, is_approx_statistics_ok)?;
-        if let Some(projection) = asset.extension::<Projection>()? {
+        let projection = asset.extension::<Projection>()?;
+        if !projection.is_empty() {
             has_projection = true;
             if let Some(asset_bounds) = projection.wgs84_bounds()? {
                 bbox.update(asset_bounds);
             }
             projections.push(projection);
         }
-        if !has_raster && asset.has_extension::<Raster>() {
+        if !has_raster && !asset.extension::<Raster>()?.is_empty() {
             has_raster = true;
         }
     }
@@ -65,7 +66,7 @@ pub fn update_item(
                 .iter()
                 .all(|projection| *projection == projections[0])
         {
-            item.set_extension(projections[0].clone())?;
+            Extensions::set_extension(item, projections[0].clone())?;
             for asset in item.assets.values_mut() {
                 asset.remove_extension::<Projection>();
             }
@@ -174,7 +175,7 @@ mod tests {
     use crate::{
         extensions::{projection::Centroid, raster::DataType, Projection, Raster},
         item::Builder,
-        Extensions,
+        Extensions, Fields,
     };
 
     #[test]
@@ -185,13 +186,7 @@ mod tests {
             .unwrap();
         super::update_item(&mut item, false, true).unwrap();
         assert!(item.has_extension::<Raster>());
-        let raster: Raster = item
-            .assets
-            .get("data")
-            .unwrap()
-            .extension()
-            .unwrap()
-            .unwrap();
+        let raster: Raster = item.assets.get("data").unwrap().extension().unwrap();
         assert_eq!(
             *raster.bands[0].data_type.as_ref().unwrap(),
             DataType::UInt16
@@ -205,13 +200,7 @@ mod tests {
             .build()
             .unwrap();
         super::update_item(&mut item, false, true).unwrap();
-        let raster: Raster = item
-            .assets
-            .get("data")
-            .unwrap()
-            .extension()
-            .unwrap()
-            .unwrap();
+        let raster: Raster = item.assets.get("data").unwrap().extension().unwrap();
         assert_eq!(
             raster.bands[0].spatial_resolution.unwrap(),
             100.01126757344893
@@ -225,7 +214,7 @@ mod tests {
             .build()
             .unwrap();
         super::update_item(&mut item, false, true).unwrap();
-        let projection: Projection = item.extension().unwrap().unwrap();
+        let projection: Projection = item.extension().unwrap();
         assert_eq!(projection.code.unwrap(), "EPSG:32621");
         assert_eq!(
             projection.bbox.unwrap(),