feat(core): add item_assets to Collection

Author: gadomski

core/CHANGELOG.md

@@ -16,6 +16,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - `object_store` ([#382](https://github.com/stac-utils/stac-rs/pull/382))
 - `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))
 
 ### Changed
 

core/src/collection.rs

@@ -1,6 +1,6 @@
 use crate::{
-    Asset, Assets, Bbox, Error, Extensions, Fields, Href, Item, Link, Links, Migrate, Result,
-    Version, STAC_VERSION,
+    Asset, Assets, Bbox, Error, Extensions, Fields, Href, Item, ItemAsset, Link, Links, Migrate,
+    Result, Version, STAC_VERSION,
 };
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
@@ -87,6 +87,10 @@ pub struct Collection {
     #[serde(skip_serializing_if = "HashMap::is_empty", default)]
     pub assets: HashMap<String, Asset>,
 
+    /// A dictionary of assets that can be found in member Items.
+    #[serde(skip_serializing_if = "HashMap::is_empty", default)]
+    pub item_assets: HashMap<String, ItemAsset>,
+
     /// Additional fields not part of the `Collection` specification.
     #[serde(flatten)]
     pub additional_fields: Map<String, Value>,
@@ -182,6 +186,7 @@ impl Collection {
             summaries: None,
             links: Vec::new(),
             assets: HashMap::new(),
+            item_assets: HashMap::new(),
             additional_fields: Map::new(),
             href: None,
         }

core/src/item_asset.rs

@@ -0,0 +1,54 @@
+use serde::{Deserialize, Serialize};
+use serde_json::{Map, Value};
+
+/// An item asset is an object that contains details about the datafiles that
+/// will be included in member items.
+///
+/// Assets included at the Collection level do not imply that all assets are
+/// available from all Items. However, it is recommended that the Asset
+/// Definition is a complete set of all assets that may be available from any
+/// member Items. So this should be the union of the available assets, not just
+/// the intersection of the available assets.
+///
+/// Other custom fields, or fields from other extensions may also be included in the Asset object.
+///
+/// Any property that exists for a Collection-level asset object must also exist
+/// in the corresponding assets object in each Item. If a collection's asset
+/// object contains properties that are not explicitly stated in the Item's
+/// asset object then that property does not apply to the item's asset. Item
+/// asset objects at the Collection-level can describe any of the properties of
+/// an asset, but those assets properties and values must also reside in the
+/// item's asset object. To consolidate item-level asset object properties in an
+/// API setting, consider storing the STAC Item objects without the larger
+/// properties internally as 'invalid' STAC items, and merge in the desired
+/// properties at serving time from the Collection-level.
+///
+/// At least two fields (e.g. title and type) are required to be provided, in
+/// order for it to adequately describe Item assets. The two fields must not
+/// necessarily be taken from the defined fields on this struct and may include
+/// any custom field.
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
+pub struct ItemAsset {
+    /// The displayed title for clients and users.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+
+    /// A description of the Asset providing additional details, such as how it
+    /// was processed or created.
+    ///
+    /// CommonMark 0.29 syntax MAY be used for rich text representation.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+
+    /// Media type of the asset.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub r#type: Option<String>,
+
+    /// The semantic roles of the asset, similar to the use of rel in links.
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    pub roles: Vec<String>,
+
+    /// Additional fields.
+    #[serde(flatten)]
+    pub additional_fields: Map<String, Value>,
+}

core/src/lib.rs

@@ -168,6 +168,7 @@ pub mod geoparquet;
 mod href;
 pub mod io;
 pub mod item;
+mod item_asset;
 mod item_collection;
 mod json;
 pub mod link;
@@ -193,6 +194,7 @@ pub use {
     href::Href,
     io::{read, write},
     item::{FlatItem, Item, Properties, ITEM_TYPE},
+    item_asset::ItemAsset,
     item_collection::{ItemCollection, ITEM_COLLECTION_TYPE},
     json::{FromJson, ToJson},
     link::{Link, Links},